Vodik nema određen položaj u periodnom sustavu. Ima jedan valentni elektron, kao alkalijski metali, a od njih se razlikuje mnogo većom energijom ionizacije. Za stabilnu elektronsku konfiguraciju nedostaje mu jedan elektron. Vodik bi se mogao smatrati halogenim elementom, ali ima manju elektronegativnost i afinitet prema elektronu, stoga se proučava zasebno. Čini 75% mase svemira i ishodišna je tvar iz koje su nuklearnom fuzijom nastali ostali elementi. Zvijezde u glavnom nizu sastoje se uglavnom od vodika u obliku plazme. Elementarni se vodik na Zemlji nalazi u vrlo malim količinama.Palmer D. "Hydrogen in the Universe"  publisher=NASA, 1997.

Elementarni se vodik sastoji od običnog vodika (procija (P)) (>99,98%), a ostatak (gotovo 0,02%) čini teški vodik (deuterij (D)) s tragovima superteškog vodika (tricija (T)). Vodik stvara kemijske veze s najviše elemenata, posebno u organskim tvarima. Pri standardnom tlaku i temperaturi, vodik je plin bez boje, mirisa i okusa, 14,4 puta lakši od zraka, neotrovan je. Slabo je topljiv u polarnim, a dobro u nepolarnim otapalima.
mini|Ispitivanje spektra vodika
Industrijski se najviše dobiva iz zemnog plina, a rjeđe elektrolizom vode. Najviše se koristi u proizvodnji fosilnih goriva (hidrokrekiranje – povećanje kvalitete goriva) i za dobivanje amonijaka (proizvodnja umjetnih goriva). U metalurgiji nije baš poželjan jer mnoge metale čini lomljivim i krtim, dakle stvara poteškoće u izgradnji cjevovoda i metalnih spremnika."Hydrogen Basics — Production"  publisher=Florida Solar Energy Center, 2007.Rogers H.C.: "Hydrogen Embrittlement of Metals", journal=Science, 1999.

 Povijest
Iako ga nije prvi proizveo (prvi ga je proizveo Paracelsus u 16. st. reakcijom metala i jake kiseline), vodik (lat. Hydrogenium) je definirao Britanac Henry Cavendish 1766.Opća i nacionalna enciklopedija u 20 svezaka, sv. 20, , str. 281 i nazvao ga "zapaljivim zrakom". Cavendish ga je dobio reakcijom cinka i klorovodične kiseline. Definirao je o kojem se plinu radi i dokazao da reakcijom vodika i kisika nastaje voda. Zbog tog svojstva Antoine Lavoisier 1783. naziva ga hydrogène, od grčkog "onaj koji stvara vodu" (grč. ὕδωρ = voda, γενής = stvaratelj). Hrvatski je naziv uveo Bogoslav Šulek.

Tekući vodik prvi je put 1898. dobio James Dewar, a godinu kasnije stvorio je i čvrsti vodik. Deuterij je 1931. dobio Harold Urey, a godinu kasnije stvorio je i tešku vodu. 1934. Ernest Rutherford i njegov tim proizveli su tricij.Emsley John: "Nature's Building Blocks", publisher=Oxford University Press, 2001.
500px|desno|mini|Vodikove emisione linije u vidljivom dijelu spektra. Postoje 4 vidljive linije Balmerove serije
Prvi je balon na vrući zrak 1783. otkrio Jacques Charles. Ferdinand von Zeppelin napravio je letjelicu na vodik, koja je prvi let imala 1900., kasnije je nazvana cepelin.

Nikal – vodikove su se baterije prvi puta koristile 1977., a kasnije se njima koristila Međunarodna svemirska postaja, svemirske letjelice 2001 Mars Odyssey i Mars Global Surveyor te svemirski teleskop Hubble, čije je prvo pakovanje baterija trajalo 19 godina.  "NTS-2 Nickel-Hydrogen Battery Performance 31", publisher=Aiaa.org, 2009.
desno|mini|300px|NGC 604 galaksija, ogromno područje ioniziranog vodika u zviježđu Trokut
Uloga u kvantnoj teoriji
Zbog svoje jednostavne atomske strukture koja se sastoji od jednog protona i elektrona, atom je vodika sa svojim vodikovim spektralnim linijama svjetlosti (emisija i apsorpcija – Balmerova serija, Lymanova serija itd.), imao središnju ulogu u razvoju teorije atomske strukture. Osim toga, atom vodika i odgovarajući kationi H+ imali su važnu ulogu u razumijevanju prirode kemijskih veza čija se teorija razvila 1920-ih.Crepeau Bob: "Niels Bohr: The Atomic Model", journal=Great Scientific Minds, publisher=Great Neck Publishing, 2006.

Prije razvoja kvantne mehanike, Maxwell je uočio da specifični toplinski kapacitet molekule H2 ima neobjašnjivo odstupanje na niskim temperaturama, gdje se H2 počinje više ponašati kao jednoatomni plin. Prema kvantnoj teoriji, ta se pojava događa zbog prostora energetskih razina, koji su naširoko raspoređeni kod H2 zbog male mase. Taj velik prostor energetskih razina onemogućuje ravnomjernu raspodjelu toplinske energije vodika na niskim temperaturama.Berman R., Cooke, A. H.; Hill, R. W.: "Cryogenics", journal=Annual Review of Physical Chemistry, 1956.

 Svojstva
Pri standardnom je tlaku i temperaturi vodik plin bez boje, mirisa i okusa, 14.4 puta lakši od zraka, neotrovan je. Slabo je topljiv u polarnim, a dobro u nepolarnim otapalima.

Ohlađen na temperaturu vrelišta, kondenzira se u bezbojnu tekućinu koja je najlakša od svih tekućina. Daljnjim se odvođenjem topline skrućuje u proziran solid heksagonske kristalne strukture.

Zapaljen na zraku pri 560 °C, izgara gotovo nevidljivim plamenom u vova prema reakciji:

2 H2(g) + O2(g) → 2 H2O(l)  = 286 kJ mol−1

Na sobnoj temperaturi nije previše reaktivan, no pri višim temperaturama ulazi u niz reakcija. Otapa se u mnogim metalima. Pri sobnoj temperaturi, bez katalizatora, reagira samo s fluorom i vanadijem u prahu. Razlog slaboj reaktivnosti molekularnog vodika pri sobnoj temperaturi jaka je jednostruka kovalentna veza u molekuli. Ta je veza najjača od svih jednostrukih kovalentnih veza između dvaju istovrsnih atoma. Pri povišenoj temperaturi spaja se s kisikom iz mnogih oksida, stoga djeluje kao redukcijsko sredstvo.
mini|desno|250px|Niz proton-proton prevladava kod zvijezdi veličine našeg Sunca ili manjih

 Rasprostranjenost
Elementarni je vodik na Zemlji vrlo rasprostranjen, ali u malim količinama. Prisutan je u atmosferi, zemnom plinu, vulkanskim plinovima, itd. U gornjim dijelovima atmosfere izlazi u svemir jer ga gravitacija teško zadržava.

U obliku spojeva prisutan je u velikim količinama, ponajviše u obliku vode, koja prekriva gotovo dvije trećine Zemljine površine. Sastavni je dio mnogih organskih spojeva, kiselina i otopina.

Čini 75% mase svemira, te je ishodišna tvar iz koje su nuklearnom fuzijom nastali ostali elementi. Po broju atoma, vodika ima 90% u svemiru. Ima ga u ogromnim količinama u zvijezdama i plinovitim divovima, a izgleda da ga ima u još neotkrivenoj tamnoj tvari i tamnoj energiji. Molekularni oblaci s H2 su povezani s rođenjem zvijezda. Vodik ima odlućujuću ulogu u stvaranju snage i toplinske energije u nuklearnoj fuziji, koja se odvija u jezgrama zvijezda, kroz niz proton – proton i niz ugljik – dušik – kisik.Steve Gagnon:  "Hydrogen", publisher=Jefferson Lab, 2008.Haubold Hans, Mathai, A. M., 2007.   "Solar Thermonuclear Energy Generation", publisher=Columbia University, 2008.

U svemiru vodik se uglavnom nalazi u atomskom stanju ili kao plazma, čija su svojstva sasvim drukčija od molekularnog vodika H2. Kao plazma, vodikovi elektroni i protoni nisu povezani zajedno, i stvaraju veoma jaku električnu vodljivost i veliku emisiju topline (stvara elektromagnetsko zračenje, uključujući svjetlost sa Sunca i ostalih zvijezda). Na nabijene čestice vodika snažno utječu magnetska i električna polja. Na primjer, Sunčev vjetar djeluje na Zemljinu magnetosferu, stvarajući polarnu svjetlost i Birkelandovu struju.Storrie-Lombardi Lisa J.: "Surveys for z > 3 Damped Lyman-alpha Absorption Systems: the Evolution of Neutral Gas", journal=Astrophysical Journal, 2000.

Pod normalnim uvjetima na Zemlji, vodik se uglavnom nalazi kao plinovita molekula H2. Ustvari, vodikov plin je vrlo rijedak u atmosferi, svega 0,000055%, zato što je molekula vodika puno lakša od zraka, zbog čega lakše bježi iz atmosfere. Ipak, na Zemljinoj površini, vodik je treći najrašireniji element, uglavnom u obliku molekula vode i ugljikohidrata. Neke alge i bakterije stvaraju plin vodik.Wolfgang H. Berger, 2007.  "The Future of Methane", publisher=University of California, San Diego, 2008.

 Dobivanje
 Laboratorijsko
Najčešće se dobiva onako kako ga je prvi put dobio Cavendish, tj. reakcijom cinka i klorovodične kiseline, umjesto koje se često rabi i razrijeđena sumporna kiselina:

Zn(s) + 2 H+ → Zn2+ + H2(g)

Za razvijanje plinova u laboratoriju najpogodniji je Kippov aparat, jer se reakcija u njemu može prekinuti i na taj način proizvesti samo potrebne količine plina.

Može se dobiti i reakcijom vode s čvrstim hidridima, kao što je kalcijev hidrid:

2 H2O + CaH2(s) → 2 H2(g) + Ca2+ + 2 OH-

te reakcijom metala negativnog redukcijskog potencijala s lužinama, ako ti metali stvaraju hidrokso-komplekse:

2 Al(s) + 6 H2O + 2 OH- → 2 Al(OH)4- + 3 H2(g)

 Industrijsko
Ovisno o cijeni električne energije i energenata, vodik se dobiva na nekoliko načina.

U zemljama s jeftinom električnom energijom, dobiva se elektrolizom vode, zalužene alkalijskim hidroksidom zbog povećanja vodljivosti:

katoda (-): 4 H20 + 4e- → 2 H2(g) + 4 OH-
anoda (+): 4 OH- → O2(g) 2 H2O + 4e-
2 H2O → 2 H2(g) + O2(g)

Vodik se dobiva i kao nusprodukt kod dobivanja klora metodom kloralkalne elektrolize.

Jedna od najraširenijih i najjeftinijih metoda jest piroliza ugljikovodika, primjerice etana:

C2H2(g) → C2H4(g) + H2(g)

Kada je lako dostupan metan, koristi se njegova reakcija s vodenom parom na 1100 °C:

CH4(g) + H2O ⇄ CO(g) + 3 H2(g)  = 214.4 kJ mol−1

Kada je lako dostupan i jeftin ugljen, koristi se redukcija vodene pare:

C(s) + H2O ⇄ CO(g) + H(g)  = 131.25 kJ mol−1
mini|desno|300px|Bioreaktor s algama za proizvodnju vodika
Dobivena smjesa zove se vodeni plin.

Ugljikov(II) oksid od vodika se odvaja reakcijom s dodatnom vodenom parom, pri čemu nastaje dodatna količina vodika:

CO(g) + H2O(g) → H2(g) + CO2(g)

Nastali ugljikov(IV) oksid uklanja se iz smjese apsorpcijom u lužini ili ispiranjem vodom pod tlakom. Lako se uklanja i hlađenjem tekućim zrakom. Tragovi neizreagiranog ugljikovog(II) oksida uklanjaju se prevođenjem plina preko zagrijanog natrijevog hidroksida pri čemu nastaje natrijev metanoat.

Termokemijski procesi
Postoji više od 200 termokemijskih procesa, koji se mogu iskoristiti za razdvajanje vode. Desetak procesa istražuje se i ispituje za dobivanje vodika i kisika iz vode, te grijanjem bez upotrebe električne struje, a ti su procesi na primjer: ciklus željeznog oksida, ciklus cerij (IV) oksid - cerij (III) oksid, ciklus cink – cink oksid, ciklus sumpor – jod, ciklus bakar – klor i ciklus hibridni sumpor. Veliki broj labaratorija u Francuskoj, Njemačkoj, Grčkoj, Japanu i SAD razvijaju termokemijske procese uz korištenje Sunčeve energije i vode. "Development of solar-powered thermochemical production of hydrogen from water"[url=http://www.hydrogen.energy.gov/pdfs/progress07/ii_f_1_perret.pdf] "Development of Solar-Powered Thermochemical Production of Hydrogen from Water", DOE Hydrogen Program, 2007., Perret Robert, 2008.

Anaerobna korozija
mini|desno|250px|U spremniku je tamno zeleni željezo(II) hidroksid ili zelena korozija
Bez prisustva kisika, željezo i legirani čelik polako oksidiraju uz pomoć protona iz vode, koji se pretvaraju u plinoviti vodik H2. Anaerobna korozija stvara prvo željezni hidroksid (zelena korozija) i ta se kemijska reakcija može opisati kao:
Fe + 2 H2O → Fe(OH)2 + H2
U drugom koraku, bez prisustva kisika, željezni hidroksid može oksidirati uz pomoć protona iz vode i stvoriti magnetit i plinoviti vodik. Taj se proces naziva Shikorrova reakcija:
3 Fe(OH)2 → Fe3O4 + 2 H2O + H2
Dobro kristalizirani magnetit (Fe3O4) je termodinamički puno stabilniji od željeznog hidroksida. Taj se proces obično dešava za vrijeme anaerobne korozije željeza i čelika, u podzemnim vodama koje nemaju kisika, i u reduciranim tlu u kojem ima dosta vlage.

Geološko stvaranje – serpentacija
Bez prisustva kisika, u dubokim geološkim slojevima, koji su daleko od Zemljine atmosfere, plinoviti vodik se stvara za vrijeme procesa serpentacije, što je anaerobna oksidacija protona vode (H+) i željeznog (Fe2+) silikata, koji je prisutan u kristalima fajalita (Fe2SiO4 – krajnji član olivina). Ta reakcija vodi do stvaranja magnetita (Fe3O4), kvarca (SiO2) i vodika (H2), na sljedeći način:
3 Fe2SiO4 + 2 H2O → 2 Fe3O4 + 3 SiO2 + 3 H2

 Spojevi
250px|desno|mini|Model vodikovih veza (1) kod molekula vode.
Spojevi vodika mogu se podijeliti na spojeve u kojima je nazočan u negativnom (-1) i pozitivnom stupnju oksidacije (+1).
Prvi se nazivaju hidridima, i zauzimaju manjinu vodikovih spojeva, dok su drugi puno zastupljeniji i važniji. Sastavni je dio živog svijeta, u kojem igra jednu od temeljnih uloga.
Poznati spojevi su vodikov peroksid i vodikov praskavac.

Kovalentni i organski spojevi
Na sobnoj temperaturi nije previše reaktivan, no pri višim temperaturama ulazi u niz reakcija. Poznati su milijunu ugljikovodika, koji su područje proučavanja organske kemije. Vodik stvara spojeve i s elementima koji imaju veću elektronegativnost, kao što su halogeni elementi (F, Cl, Br, I). Kada se spaja s fluorom, kisikom ili dušikom, vodik se može vezati u jakoj nekovalentnoj vezi, koja se zove vodikova veza, koja je kritična u stabilnosti mnogih bioloških molekula. Vodik se veže i s manje elektronegativnim elementima, kao što su metali i polumetali.

Hidridi
Hidridi su spojevi raznih kemijskih elemenata s vodikom. S-blok čine elementi prve i druge skupine periodnog sustava elemenata. P-blok čine elementi 13. – 17. skupine periodnog sustava elemenata. To su najvažniji hidridi, često korišteni u praksi. Dijele se na kisele, bazne, amfoterne i neutralne. Kiseli hidridi su oni hidridi koji u reakciji s vodom daju kiseline. Bazni hidridi su oni hidridi koji u reakciji s vodom daju baze. Amfoterni hidridi, ovisno o reakciji, mogu se ponašati i kao kiseline i kao baze. Neutralni hidridi uopće ne reagiraju s vodom

 Izotopi
mini|200px|desno|Sat s luminiscentnom bojom od tricija
Elementarni vodik sastoji se od običnog vodika (procija) (>99,98%), dok ostatak (gotovo 0,02%) čini teški vodik (deuterij)  s tragovima superteškog vodika (tricija).
1H ili procij je daleko najčešći izotop vodika, kojeg ima više od 99,98%. Ima jedan proton i jedan elektron. Za razliku od svih ostalih izotopa, nema neutron.
2H ili deuterij, ima jedan proton i jedan neutron u jezgri, te jedan elektron. U biti, vjeruje se da sav deuterij u svemiru potječe još od vremena Velikog praska i da još traje. Deuterij nije radioaktivan, i ne prestavlja značajnu opasnost za zdravlje. On se koristi i kod nuklearne magnetno rezonantne spektroskopije, za označavanje neradioaktivnih tvari u otapalu. Voda koja uključuje atome deuterija se naziva teška voda. Teška voda se koristi u nuklearnim reaktorima za smanjivanje brzine brzih neutrona, kao i za hlađenje nuklearnih reaktora. Deuterij prestavlja moguće gorivo za dobivanje električne energije iz nuklearne fuzije.
3H ili tricij, ima jedan proton i dva neutrona u jezgri, te jedan elektron.Tricij je radioaktivan, raspada se u helij-3 izotop, uz pojavu beta-čestica i ima vrijeme poluraspada od 12,32 godine. Toliko je radioaktivan da se koristi za luminiscentne boje, koje se koriste i kod satova, kod kojih se može vidjeti vrijeme i u mraku. Staklo sprječava da mala količina radioaktivnosti izađe van. U prirodi se tricij može naći u vrlo malim količinama u atmosferi, a nastaje zbog djelovanja kozmičkih zraka. Tricij može nastati kod testiranja nuklearnog oružja. Tricij prestavlja moguće gorivo za dobivanje električne energije iz nuklearne fuzije. On se koristi kod kemijskih i bioloških pokusa kao radioaktivni označivač.

Vodik je jedini kemijski element čiji se izotopi označuju drugim imenima (procij, deuterij, tricij). Međunarodna unija za čistu i primijenjenu kemiju dozvoljava oznake D za deuterij ili T za tricij, ali preporučuje oznake 2H i 3H. Oznaka P se već koristi za fosfor, tako da se ne može koristiti za procij.

 Molekularni izomeri
Prilikom ispitivanja vibracijsko-rotacijskog spektra vodika pronađene su promjene u intenzitetu rotacijskih vrpci, koje su protumačene hipotezom o postojanju dva oblika vodika koji se razlikuju po nuklearnim spinovima u molekuli vodika. Ako su spinovi dvaju protona iz molekule antiparalelni, rezultantni spin je nula, te je stanje nedegenerirano. Takav vodik zove se para-vodik. Ako su paralelni, rezultantni spin je 1, a stanje je trostruko degenerirano, što dovodi do orto-vodika.
Pri sobnoj temperaturi, elementarni se vodik sastoji od 75% orto-vodika i 25% para-vodika. Orto- i para-vodik razlikuju se po nekim fizikalnim svojstvima, primjerice energiji disocijacije, toplinskom kapacitetu, tlaku para i slično.

Između njih postoji ravnoteža:

o-H2 ⇄ p-H2  < 0

koja se hlađenjem pomiče udesno.

Na niskim temperaturama moguće je izolirati gotovo čisti para-vodik, no čisti orto-vodik nije moguće izolirati, jer povećanjem temperature ne dolazi do povećanja njegovog udjela iznad 75%.

Odnos između orto- i para-vodika je vrlo bitna kod spremanja tekućeg vodika u spremnik, jer pretvaranje orto-vodika u para-vodik stvara dodatno toplinu, koja može dovesti do hlapljenja, a time i gubitka tekućeg vodika. Zbog toga treba koristiti katalizatore, kao što je željezov (III) oksid, aktivni ugljik, platinizirani azbest, kovine rijetkih zemalja, uranovi spojevi, kromov oksid i neki spojevi nikla.

Molekularni oblik iona triatomnog vodika ili H3+, je pronađen u međuzvjezdanoj materiji, koji je nastao ionizacijom vodika s kozmičkim zrakama. Također, taj oblik molekule je pronađen u gornjoj atmosferi Jupitera. Ona je dosta stabilna u tim okolinama, zbog malih temperatura i gustoće. To je jedan od najraširenijih iona u svemiru.

 Primjena
Vodik je vrlo važna industrijska sirovina. Koristi se, između ostalog, za sintezu amonijaka i metanola, za proizvodnju goriva za motorna vozila hidrogenacijom ugljika, nafte i katrana. Koristi se i za zavarivanje i taljenje metala, za punjenje zračnih balona i zračnih brodova, za redukciju metalnih oksida u metale, hidrogeniranje ulja u masti itd.

Radi se na korištenju vodika kao goriva. Tehnologija je vrlo slabo rasprostranjena.

Prednosti vodika kao goriva su:
visoka energetska vrijednost
neograničene količine dostupne u spojevima
izgaranjem daje kemijski čistu vodu
cjevovodima se može razvoditi na daljinu
lakše se skladišti i čuva nego električna energija

Nedostaci koji sprječavaju rašireniju uporabu su:
visoka cijena i često slaba isplativost izvlačenja vodika iz spojeva
obilno curenje vodika kroz spremnike i cjevovode, zbog ekstremo malene molekule
vodik difundiranjem u razne metale narušava njihovu kristalnu rešetku čineći ih krtima
opasnost za ozonski sloj jer trenutno reducira ozon u vodu

U kemijskom smislu, vodik nije izvor, već spremnik energije, jer nije prirodno nabavljiv u elementarnom obliku. U slučaju uspješne i održive nuklearne fuzije u nuklearnoj elektrani, bio bi izvor ogromnih količina energije.

Velike količine H2 se koriste u naftnoj i kemijskoj industriji. Najveća primjena je kod poboljšanja fosilnih goriva i u proizvodnji amonijaka. U petrokemiji H2 se koristi u procesima kao što su: hidrokrekiranje, katalitičko reformiranje benzina, izomerizacija i alkilacija. H2 se isto koristi u povećanju zasićenja nezasićenih masti i ulja (koristi se za dobivanje margarina). Također je sirovina za dobivanje klorovodične kiseline, a koristi se i kao reducens za mineralne sirovine ili rude.Chemistry Operations: 2003.  "Hydrogen|publisher=Los Alamos National Laboratory" 2008.

Vodik je izuzetno topiv u mnogim kovinama rijetkih zemalja i prijelaznim metalima, a topiv je i u nanokristalima i amorfnim metalima. Topljivost u metalima utječe na lokalne deformacije ili nečistoće u kristalnim rešetkama, tako da metali postaju krtiji i lomljiviji, što stvara velike probleme u metalurgiji, u izradi cjevovoda i metalnih rezevoara.  Ponekad se to može riješiti ako vodik se pročisti prolaskom kroz diskove paladija.Takeshita Wallace: "Hydrogen solubility in 1:5 compounds between yttrium or thorium and nickel or cobalt", journal=Inorganic Chemistry, 1974.

Plinoviti vodik H2 se koristi za hlađenje rotora električnih generatora u elektranama, zato što ima najveću toplinsku provodljivost od svih plinova. Tekući H2 se koristi u ispitivanju supravodljivosti kod vrlo niskih temperatura. Budući da je plinoviti vodik H2 skoro 15 puta lakši od zraka, nekad se koristio za balone na vrući zrak.

U novije vrijeme, plinoviti vodik H2 se miješa s dušikom, za dobivanje formirajućeg plina (oko 5% vodika u dušiku), koji se koristi kod postupka lociranja ili utvrđivanja propuštanja kod raznih cjevovoda u automobilskoj, kemijskoj industriji, elektranama, zrakoplovstvu i telekomunikacijama. Vodik se koristi kao dodatak hrani (E 949) za provjeru konzervirane hrane.Matthias Block: "Hydrogen as Tracer Gas for Leak Detection", publisher=Sensistor Technologies, 2004.

Trojna točka vodika u ravnoteži iznosi 13, 8033 Kelvina.

Nosilac energije
mini|desno|250px|Mercedes-Benz O530 Citaro autobus kojeg pogone vodikove gorive ćelije, u Brno, Češka.
Vodik nije izvor energije, osim u mogućim elektranama na nuklearnu fuziju, koje bi koristile deuterij i tricij, što je još daleko od komercijalne upotrebe. Vodik koji se dobije iz sunčevih, bioloških ili električnih izvora, treba više energije nego što od njega možemo dobiti izgaranjem, zato on više ima ulogu kao baterija, za spremanje ili skladištenje energije. Vodik se može dobiti iz metana, ali ti se izvori nazivaju neodrživim izvorima energije.McCarthy John: "Hydrogen", publisher=Stanford University, 1995

Gustoća energije po jedinici obujma, za tekući ili komprimirani vodik, je puno manja od poznatih fosilnih goriva, iako po jedinici mase, gustoća energije je veća. Ipak, o vodiku se dosta raspravlja kao o budućem nosiocu energije. Tako recimo, vezivanjem ugljikovog dioksida iz zraka, može biti povezano sa stvaranjem H2 kao fosilnog goriva. Tada bi vodik bio relativno čisti izvor energije, uz malo ispuštanje dušikovih oksida, ali bez stvaranja ugljikovog dioksida. Ipak, ulaganje u infrastrukturu bi bilo znantno."DOE Seeks Applicants for Solicitation on the Employment Effects of a Transition to a Hydrogen Economy", publisher=US Department of Energy, 2006.

Proizvodnja poluvodiča
U proizvodnji poluvodiča, vodik se koristi za zasićenje slomljenih (“klimavih”) veza u amorfnom siliciju i amorfnom ugljiku, da bi im se povećala kvaliteta. On je isto mogući dodatak u različitim oksidima, kao: ZnO, SnO2, CdO, MgO, ZrO2, HfO2, La2O3, Y2O3, TiO2, SrTiO3, LaAlO3, SiO2, Al2O3, ZrSiO4, HfSiO4 i SrZrO3.Van de Walle: "Hydrogen multicentre bonds", journal=Nature Materials, 2007.

 Biološka uloga
Kao sastojak vode, nalazi se u svakom biološkom organizmu u velikim količinama. Osim u vodi, nalazi se i u gotovo svim organskim spojevima unutar organizma, vezan kovalentno za primjerice ugljik ili dušik. U vodenim otopinama koje su dio svakog organizma, nazočan je u obliku H3O+ iona, te kao takav ima izvanredno važnu, temeljnu ulogu u regulaciji staničnih procesa.

H2 se stvara kod nekih vrsta vrenja ili fermentacija, a stvaraju ga neki mikroorganizmi, obično uz pomoć katalizatora, koje sadrže enzime sa željezom ili niklom, koji se nazivaju hidrogenaze.

Razdvajanje vode u protone, elektrone i kisik, javlja se kod gotovo svih biljaka koje vrše fotosintezu. Neki takvi organizmi, kao modrozelene alge su razvile i drugi korak, po mraku, kojim se stvara plinoviti vodik H2 uz pomoć specijalnih hidrogenaza u kloroplastu. Trenutno se rade ispitivanja na genetski modificiranim modrozelenim algama, koje bi stvarale H2, čak i u prisustvu kisika ili takozvani bioreaktori.Williams Chris; "Pond life: the future of energy", publisher=The Register, 2006.

Sigurnost i mjere opreza
Vodik stvara čitav niz opasnosti za čovjekovu sigurnost, pogotovo H2 je opasan kao plin praskavac u zraku. Osim toga, tekući vodik je opasan, jer stvara vrlo niske temperature, što može dovesti do smrzotina."Hydrogen Safety", publisher=Humboldt State University,  , 2010.

 Izvori

 Vanjske poveznice
Vodik (PSE) - Kemijsko-tehnološki fakultet Split

Kategorija:Kemijski elementi

For a stable electron configuration, it lacks one electron.

Water could be considered a halogenic element, but it has less electron-negativity and affinity to the electron, so it is studied separately.

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Question: which element has less electron negativity and affinity to the electron

For a stable electron configuration, it lacks one electron.

Water could be considered a halogenic element, but it has less electron-negativity and affinity to the electron, so it is studied separately.

which element has less electron negativity and affinity to the electron

Question: how many electrons does vodik have in it

how many electrons does vodik have in it

Question: what type of element is water in vodik

Question: why is water a halogenic element

Question: what type of electron does vodik have

Question: why is water considered a halogenic element

it has less electron-negativity and affinity

it has less electron - negativity and affinity

why is water considered a halogenic element

Question: does vodik have more or less electron negativity

does vodik have more or less electron negativity

For a stable electron configuration , it lacks one electron .

Water could be considered a halogenic element , but it has less electron - negativity and affinity to the electron , so it is studied separately .

Za stabilnu elektronsku konfiguraciju nedostaje mu jedan elektron.

Vodik bi se mogao smatrati halogenim elementom, ali ima manju elektronegativnost i afinitet prema elektronu, stoga se proučava zasebno.

For a stable electron configuration, it lacks one electron. Water could be considered a halogenic element, but it has less electron-negativity and affinity to the electron, so it is studied separately.

For a stable electron configuration, it lacks one electron.

Water could be considered a halogenic element, but it has less electron-negativity and affinity to the electron, so it is studied separately.

It is mostly used in the production of fossil fuels (hydrocreation – increased fuel quality) and for the production of ammonia (production of artificial fuels).

Question: what is the use of vodik in the production of artificial fuels

It is mostly used in the production of fossil fuels (hydrocreation – increased fuel quality) and for the production of ammonia (production of artificial fuels).

what is the use of vodik in the production of artificial fuels

Question: where does the name vodik come from

Question: what is the main use of vodik in fuel production

what is the main use of vodik in fuel production

Question: what is the purpose of vodik in fossil fuels

what is the purpose of vodik in fossil fuels

Question: what are the problems with vodik in metallurgy

what are the problems with vodik in metallurgy

Question: when was the first vodik published in science

when was the first vodik published in science

Question: what is produced by vodik in the form of ammonia

what is produced by vodik in the form of ammonia

It is mostly used in the production of fossil fuels ( hydrocreation – increased fuel quality ) and for the production of ammonia ( production of artificial fuels ) .

In metallurgy it is not very desirable because many metals make it broken and broken , thus it creates difficulties in the construction of tubes and metal tanks . "Hydrogen Basics — Production " publisher = Florida Solar Energy Center , 2007.Rogers H.C. : " Hydrogen Embrittlement of Metals " , journal = Science , 1999 .

Najviše se koristi u proizvodnji fosilnih goriva (hidrokrekiranje – povećanje kvalitete goriva) i za dobivanje amonijaka (proizvodnja umjetnih goriva).

It is mostly used in the production of fossil fuels (hydrocreation – increased fuel quality) and for the production of ammonia (production of artificial fuels). In metallurgy it is not very desirable because many metals make it broken and broken, thus it creates difficulties in the construction of tubes and metal tanks."Hydrogen Basics — Production" publisher=Florida Solar Energy Center, 2007.Rogers H.C.: "Hydrogen Embrittlement of Metals", journal=Science, 1999.

It is mostly used in the production of fossil fuels (hydrocreation – increased fuel quality) and for the production of ammonia (production of artificial fuels).

The hydrogen batteries were first used in 1977, and later were used by the International Space Station, the 2001 Mars Odyssey and Mars Global Surveyor spacecraft, and the Hubble spacecraft, whose first battery package lasted 19 years.

Question: when did the first vodik come out

Question: how long did the first vodik battery last

how long did the first vodik battery last

Question: how many years did the hubble battery last

how many years did the hubble battery last

Question: what type of battery is used on the international space station

what type of battery is used on the international space station

Question: what is the name of the space station that uses vodik batteries

svemirske letjelice 2001 Mars Odyssey i Mars Global Surveyor te svemirski teleskop Hubble

what is the name of the space station that uses vodik batteries

Question: what space station is powered by vodik batteries

what space station is powered by vodik batteries

Question: what are the two spacecraft that used vodik

2001 Mars Odyssey and Mars Global Surveyor

2001 Mars Odyssey i Mars Global Surveyor

2001 Mars Odyssey and Mars Global Surveyor

what are the two spacecraft that used vodik

Question: who uses the vodik battery on the space station

who uses the vodik battery on the space station

The hydrogen batteries were first used in 1977 , and later were used by the International Space Station , the 2001 Mars Odyssey and Mars Global Surveyor spacecraft , and the Hubble spacecraft , whose first battery package lasted 19 years .

According to the number of atoms, hydrogen contains 90% in the space.

It has it in enormous amounts in stars and gas wilds, and it seems to have it in still uncovered dark matter and dark energy.

Question: what percentage of hydrogen is in the solar system

According to the number of atoms, hydrogen contains 90% in the space.

It has it in enormous amounts in stars and gas wilds, and it seems to have it in still uncovered dark matter and dark energy.

what percentage of hydrogen is in the solar system

Question: what types of energy does vodik have in it

what types of energy does vodik have in it

Question: where is vodik found in the solar system

where is vodik found in the solar system

Question: where does vodik come from in the solar system

where does vodik come from in the solar system

Question: what determines the amount of hydrogen in the space

what determines the amount of hydrogen in the space

According to the number of atoms , hydrogen contains 90 % in the space .

It has it in enormous amounts in stars and gas wilds , and it seems to have it in still uncovered dark matter and dark energy .

Po broju atoma, vodika ima 90% u svemiru.

Ima ga u ogromnim količinama u zvijezdama i plinovitim divovima, a izgleda da ga ima u još neotkrivenoj tamnoj tvari i tamnoj energiji.

According to the number of atoms, hydrogen contains 90% in the space. It has it in enormous amounts in stars and gas wilds, and it seems to have it in still uncovered dark matter and dark energy.

According to the number of atoms, hydrogen contains 90% in the space.

It has it in enormous amounts in stars and gas wilds, and it seems to have it in still uncovered dark matter and dark energy.

Under normal conditions on Earth, hydrogen is mainly found as a gas molecule H2.

Question: what is the name of the gas molecule found in earth's atmosphere

Under normal conditions on Earth, hydrogen is mainly found as a gas molecule H2.

what is the name of the gas molecule found in earth's atmosphere

Question: what percentage of hydrogen gas is found in the atmosphere

what percentage of hydrogen gas is found in the atmosphere

Question: the hydrogen molecule of vodik is lighter than which other molecule

the hydrogen molecule of vodik is lighter than which other molecule

Question: what is the advantage of hydrogen gas in the atmosphere

what is the advantage of hydrogen gas in the atmosphere

Question: what type of molecule is hydrogen in the atmosphere

what type of molecule is hydrogen in the atmosphere

Question: how rare is hydrogen gas in the atmosphere

how rare is hydrogen gas in the atmosphere

Question: why is hydrogen gas rare in the atmosphere

why is hydrogen gas rare in the atmosphere

Question: what is the most common gas molecule in earth's atmosphere

what is the most common gas molecule in earth's atmosphere

Under normal conditions on Earth , hydrogen is mainly found as a gas molecule H2 .

In fact , hydrogen gas is very rare in the atmosphere , only 0.000055 % , because the hydrogen molecule is much lighter than the air , which makes it easier to escape from the atmosphere .

Pod normalnim uvjetima na Zemlji, vodik se uglavnom nalazi kao plinovita molekula H2.

Ustvari, vodikov plin je vrlo rijedak u atmosferi, svega 0,000055%, zato što je molekula vodika puno lakša od zraka, zbog čega lakše bježi iz atmosfere.

Under normal conditions on Earth, hydrogen is mainly found as a gas molecule H2. In fact, hydrogen gas is very rare in the atmosphere, only 0.000055%, because the hydrogen molecule is much lighter than the air, which makes it easier to escape from the atmosphere.

Under normal conditions on Earth, hydrogen is mainly found as a gas molecule H2.

Thermochemical processes There are more than 200 thermochemical processes that can be used to divide water.

Question: how many processes are used to divide water

Thermochemical processes There are more than 200 thermochemical processes that can be used to divide water.

how many processes are used to divide water

Question: what type of processes are used to divide water

procesi Postoji više od 200 termokemijskih

what type of processes are used to divide water

Question: what are the different processes used to divide water

what are the different processes used to divide water

Question: what two gases are produced by the vodik process

what two gases are produced by the vodik process

Question: how does the process of vodik divide water

grijanjem bez upotrebe električne struje , a ti su procesi na primjer : ciklus željeznog

how does the process of vodik divide water

Thermochemical processes There are more than 200 thermochemical processes that can be used to divide water .

A dozen processes are investigated and tested for the production of hydrogen and oxygen from water , and by heating without the use of electricity , and these processes are for example : iron oxide cycle , cery ( IV ) oxide cycle - cery ( III ) oxide , zinc cycle - zinc oxide , pump cycle - iodine , bakery cycle - chlorine and hybrid pump cycle .

Termokemijski procesi Postoji više od 200 termokemijskih procesa, koji se mogu iskoristiti za razdvajanje vode.

Thermochemical processes There are more than 200 thermochemical processes that can be used to divide water. A dozen processes are investigated and tested for the production of hydrogen and oxygen from water, and by heating without the use of electricity, and these processes are for example: iron oxide cycle, cery (IV) oxide cycle - cery (III) oxide, zinc cycle - zinc oxide, pump cycle - iodine, bakery cycle - chlorine and hybrid pump cycle.

Thermochemical processes There are more than 200 thermochemical processes that can be used to divide water.

The largest application is in fosil fuels improvement and in ammonia production.

In petrochemistry, H2 is used in processes such as: hydrocreation, catalytic reformation of gasoline, isomerization and alkilation.

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Question: what is the application of vodik in petrochemistry

The largest application is in fosil fuels improvement and in ammonia production.

In petrochemistry, H2 is used in processes such as: hydrocreation, catalytic reformation of gasoline, isomerization and alkilation.

what is the application of vodik in petrochemistry

Question: what is the use of vodik in petrochemistry

what is the use of vodik in petrochemistry

Question: what type of production is vodik used in

what type of production is vodik used in

Question: what are the applications of vodik in petrochemistry

what are the applications of vodik in petrochemistry

Question: what is the main component of vodik in petrochemistry

what is the main component of vodik in petrochemistry

Question: what type of business is vodik used in

The largest application is in fosil fuels improvement and in ammonia production .

In petrochemistry , H2 is used in processes such as : hydrocreation , catalytic reformation of gasoline , isomerization and alkilation .

Najveća primjena je kod poboljšanja fosilnih goriva i u proizvodnji amonijaka.

U petrokemiji H2 se koristi u procesima kao što su: hidrokrekiranje, katalitičko reformiranje benzina, izomerizacija i alkilacija.

The largest application is in fosil fuels improvement and in ammonia production. In petrochemistry, H2 is used in processes such as: hydrocreation, catalytic reformation of gasoline, isomerization and alkilation.

The largest application is in fosil fuels improvement and in ammonia production.

In petrochemistry, H2 is used in processes such as: hydrocreation, catalytic reformation of gasoline, isomerization and alkilation.

In recent times, gas hydrogen H2 is mixed with nitrogen, to obtain forming gas (approximately 5% of hydrogen in nitrogen), which is used in the localization process or detection of emissions at various pipelines in the automotive, chemical industry, power plants, air and telecommunications.

Question: where does h22 come from in vodik

Question: what percentage of hydrogen in nitrogen does vodik produce

what percentage of hydrogen in nitrogen does vodik produce

Question: what is the use of vodik in detection of emissions

what is the use of vodik in detection of emissions

Question: what percentage of hydrogen in nitrogen is formed by vodik

what percentage of hydrogen in nitrogen is formed by vodik

Question: what is the purpose of vodik in detection of emissions

what is the purpose of vodik in detection of emissions

Question: where is vodik used to detect emissions

Question: what gas is used in detection of emissions

what gas is used in detection of emissions

Question: where are emissions detected by vodik

automotive, chemical industry, power plants, air and telecommunications

, kemijskoj industriji , elektranama , zrakoplovstvu i telekomunikacijama

automotive , chemical industry , power plants , air and telecommunications

In recent times , gas hydrogen H2 is mixed with nitrogen , to obtain forming gas ( approximately 5 % of hydrogen in nitrogen ) , which is used in the localization process or detection of emissions at various pipelines in the automotive , chemical industry , power plants , air and telecommunications .

Water is not a source of energy, except in possible nuclear fusion power plants, which would use deutery and tricium, which is still far from commercial use.

Hydrogen is often advocated as an energy medium. Here are some relevant facts.
2H2O + energy => 2H2 + O2.
The well developed way of splitting water is by electrolysis. If fossil fuels, e.g. coal, oil or natural gas, are used to generate the electricity, there is no advantage over using the fossil fuels directly. Indeed you still get all the CO2, and there is a considerable loss of energy. Therefore, the large scale use of hydrogen depends on using either nuclear or solar electricity. In both the nuclear and solar cases, there are possible but undeveloped technologies that don't use electricity as an intermediate form of energy. [2003 September: There is a thermochemical process for splitting water that is claimed to be twice as efficient as elactrolysis. Here's an article on the sulfur-iodine cycle by Ken Schultz of General Atomic given at a Stanford University Global Climate and Energy sponsored meeting in 2003 April. To get good efficiency it requires reactors operating at a higher termperature (950 C) than present power reactors. Schultz's article also discusses solar thermal production of hydrogen. (There are also proposals to combine getting heat for houses and chemical processes and electrolysis with some saving of energy.)
Hydrogen can be transported by pipelines similar to those used to transport natural gas. There are some addtional problems, because hydrogen tends to leak more and can embrittle some metals used for pipelines. The existence of a 240 km hydrogen pipeline in Germany operated by the company Air Liquide provides evidence that these difficulties can be overcome.
In 2004 December I was informed that there is an 879km hydrogen pipeline network in Belgium, France, and the Netherlands operated by Air Liquide.However, the technology of efficient long distance transport of electric energy may be improved enough to obviate the advantages of hydrogen except for vehicles.
Nuclear power requires heavy shielding to keep the neutrons away from people - too heavy for cars. It can be used in ships, and is used in American, British and Russian warships, especially submarines and aircraft carriers. The U.S. and Japan built commercial nuclear powered ships, one each (Savannah and Mutsu). (There were even proposals to use it in locomotives.) However, initial difficulties combined with anti-nuclear politics caused these projects to be abandoned and the ships mothballed. The Soviets built nuclear powered icebreakers, and these are in use. I think nuclear power will be revived for commercial ships when its political problems are overcome and the technology is further debugged.
Solar energy can't be used directly in cars except as a stunt. The current solar-powered cars are just religious exercises in the solar religion. The problem is that a solar array of a size that can be mounted on a car produces too little energy to give useful performance, and even that little isn't available at night or when it is very cloudy.
Hydrogen can be used as a fuel directly in an internal combustion engine not much different from the engines used with gasoline. The problem is that while hydrogen supplies three times the energy per pound of gasoline it has only one tenth the density when the hydrogen is in a liquid form and very much less when it is stored as a compressed gas. This means that hydrogen fuel tanks must be large.
Demonstrations of hydrogen powered vehicles have usually used compressed hydrogen gas. However, because of the low density, compressed hydrogen will not give a car as useful a range as gasoline. It may be even worse than using lead-acid batteries. Hydrogen can achieve a reasonable density adsorbed in metal hydrides, but then the weight of the metals makes the system very heavy.
The most practical way I know of using hydrogen as a motor fuel is to accept the difficulties of handling liquid hydrogen and solve them. There are three main problems.
October 2000 note: The German automobile company BMW has just announced a car to be powered by liquid hydrogen and a plan to build a network of hydrogen refuelling stations in Germany. The car is named the 745 hdi and it is based on the BMW 745, a top-of-the-line model. A range of 350 km is promised. This is a bit small but may be tolerable. The car can also burn gasoline. BMW built a small fleet of these cars and has demonstrated them in various countries including the US, both in L.A. and Detroit.
Here's an article by BMW engineers. Oops, the link doesn't work directly as I have copied it, but the article and others can be found by Googling bmw+hydrogen.
2003 November note: Jay Keller of Sandia Laboratory presented Why hydrogen? - Building an infrastructure at the Stanford University Global Climate and Energy workshop on Hydrogen Production, Storage, and Utilization: Technical Barriers and Research Opportunities in 2003 April.
The large scale use of hydrogen for cars requires a very large investment in infrastructure. I suppose present gasoline stations can have hydrogen tanks and hydrogen pumps added, just as many gasoline stations also sell diesel fuel. Facilities for delivering hydrogen from the electrolysis plants to the users will be expensive. The transition to hydrogen will be triggered by one of two events. (1) The world will eventually run out of conventional motor fuel at reasonable prices. Opinions differ about when this will happen. Some pessimists predict a peak in world oil production in 2005. Other people think we won't run out in this century. I tend to the latter view considering that the oil sands in Alberta, Canada are being rapidly developed, produce oil profitably sellable at $12 per barrel and have resources greater than Saudi Arabia. (2) It may happen that increased CO2 causes real harm to the world and a crash program to stop emitting so much is required. There is not sufficient evidence of harm to convince governments to take drastic action in spite of the enthusiasm of the environmental community and its scientific supporters. [I can't take these proposals from these people seriously as long as they don't even mention nuclear energy. They are just playing with us.]
2003 September: A Republican draft of the energy bill includes $1.1 billion to build a nuclear reactor to produce hydrogen. That would be a big step in the right direction.
Energy and the hydrogen economy by Ulf Bossel and Baldur Eliasson analyzes the energy cost of a "hydrogen economy". The problem is that transporting energy as hydrogen uses much more energy than transporting it as oil or natural gas because of the low density of hydrogen, either as a liquid or as a compressed gas.
Bossel and Eliasson's rhetorical object seems partly to knock off the idea of a hydrogen economy in favor of their preferred methanol economy. However, they propose to get the carbon for their methanol economy from biomass. That would satisfy greenhouse objectives, whereas getting the carbon from coal would not. I'm doubtful about the biomass part, and they don't offer specific arguments for its feasibility.
New to me in their paper is the analysis of hydrogen transportation systems and their energy costs. The conclusion most interesting to me is that 2.12 times as much energy goes into generating and transporting liquid hydrogen by truck than you get into the fuel tank of the car. If their calculations are correct, the cost for the automobile user is regrettable but entirely bearable, because only a small part of the costs of operating a car are fuel costs, and a big part of the fuel price is federal and state tax.
An alternative to transporting liquid hydrogen long distances is to electrolyze water locally, perhaps in the fuel station itself.Here's what Pimentel (1996, p. 211-212) has to say.
In terms of energy contained, 9.5 kg of hydrogen is equivalent to 25kg of gasoline ( Peschka 1987). Storing 25 kg of gasoline requires a tank with a mass of 17 kg, whereas the storage of 9.5 kg of hydrogen requires 55kg, (Peschka 1987). Part of the reason for this difference is that the volume of hydrogen fuel is about 4 times greater for the same energy content of gasoline. Although the hydrogen storage vessel is large, hydrogen burns 1.33 times more efficiently than gasoline in automobiles ( Bockris and Wass 1988). In tests a BMW 745h liquid-hydrogen test vehicle with a 75 kg tank and the energy equivalent of 40 liters of gasoline had a cruising range in traffic of 400 km, or a fuel efficiency of 10 km per liter ( Winter 1986).The references above are copied from Pimentel (1996, p. 211). I plan to look them up, and this may change what I say.
At present, commercial hydrogen is more expensive than gasoline. Assuming $0.05 per kwh of electricity from a nuclear power plant during low demand, hydrogen would cost $0.09 per kwh ( Bockris and Wass 1988). This is the equivalent of $0.67 per liter of gasoline. Gasoline sells at the pump in the United States for about $0.30 per liter. However, estimates of the real cost of burning a liter of gasoline range from $1.06 to $1.32 when production, pollution, and other external costs are included (Worldwatch Institute 1989). Therefore, based on these calculations hydrogen fuel may eventually become competitive.
The above comparison between current costs of gasoline and hydrogen power for cars seems to be somewhat biased in favor of hydrogen. Taxes seem to be included in gasoline cost and not in hydrogen estimates, but roads will still have to be maintained when hydrogen is used as a fuel. Howover, I suspect the Worldwatch estimate of the "real cost" of burning a liter of gasoline is exaggerated.
For me the decisive point is that the costs of a automobile transportation system using hydrogen produced from water using nuclear energy are low enough so that people worldwide who use automobiles will not give up the freedom they provide, regardless of efforts to get people to settle for public transportation or low range and low performance cars of one kind or another. This doesn't say that adequate batteries won't be developed to make electric cars better than liquid-hydrogen internal combustion powered cars. Maybe they will, but we won't settle for less mobility than hydrogen can provide. See also my scheme for hydrogen powered Wankel engine cars. They are trying to get California to declare them zero emission with some prospect of success. However, if California chickens out of the zero emission demand (as it should and probably will), I'll bet the Mazda will not be offered for sale any time soon.
West Virginia University has a Hydrogen Review page. It mentions several ways of using hydrogen for motor vehicles. It would seem to me from their numbers that liquid hydrogen is the winner - as stated above. However, the page makes no comparisons at all.
The Department of Energy supports research on hydrogen. The value of this page seems to be somewhat limited. First, it only mentions what is currently being supported by DoE, and doesn't mention what other organizations are doing. Second, it is entirely politically correct as is apparent in the first paragraph. Nuclear energy isn't even mentioned as a possible source, not even to be dismissed. Nevertheless, there is useful information.
A check on the DoE site in 2002 February shows that there is still no mention of nuclear energy. The site still has the Clinton (or perhaps it's Gore) religion. During the California energy crisis Vice-President Cheney made a speech or two favoring nuclear energy, but the push evaporated when there turned out to be enough natural gas for the time being. I guess the Bush Administration has enough problems to occupy all its attention and has no energy left to make its Department of Energy stop ignoring a source of energy favored by the Administration. Of course, maybe it was just the Vice-President who favored it.Some companies that supply hydrogen and related technology: Air Liquide(sells gases including hydrogen), Air Products and Chemicals, Inc., The BOC Group, Praxair. Air Products and Chemicals, Inc. has a page on a hydrogen fuel celled bus in Chicago that has a range of 250 miles - enough for a whole day. This may be good enough performance for cars.
Let me reiterate that the point of this page is not to show that one particular way of powering automobiles is best but to show that there are enough ways of keeping individual mobility in the advanced countries and for the backward countries to achieve it. Cars powered by liquid hydrogen fueled internal combustion engines with the hydrogen produced by nuclear power plants electrolyzing water will suffice to preserve our mobility.
The 1999 July Scientific American has an article entitled "The electrochemical engine for vehicles" by A. John Appleby of Texas A & M University. The article concentrates on projects by the major manufacturers for powering cars. Most of them use a hydrogen-oxygen fuel cell with a platinum catalyst. They all work, but the main problems are the expense of the catalyst, the expense of the electrolyte and storing the hydrogen or making it from methane in a reformer. None are close to market. Liquid hydrogen, my favorite, is still in the running.
It is hard to know how serious these projects are even though a billion dollars will have been spent by 2000 July. It is prudent for the car companies to keep the Government appeased, and they also must hedge their bets against the possibility that governments world-wide will really force people to accept very low performance cars. None of them shows much sign of competing with the gasoline powered internal combustion engine at less than a very substantial multiple of present fuel costs.
Some schemes plan to get their hydrogen by reforming gasoline on board the vehicle. There is a chance of a slight increase in efficiency.
The article ends with
In time, we are likely to see an infrastructure for delivering hydrogen for fuel-cell powered vehicles. The result will be a more efficient, clean transportation sector, a reduction in imported oil and lower carbon dioxide emissions. A hydrogen delivery system will be built when it is technically feasible, affordable and necessary. But that point is still some years in the future.
The big taboo is on mentioning nuclear energy for splitting water as the source of hydrogen. There is no taboo about solar energy in various forms, but I doubt that these companies expect solar to succeed in producing enough energy at a reasonable cost. Most environmentalist scientists would like them to say that nuclear energy is unacceptable, but they don't want to say that - so they keep silent.
My guess is that all these companies are just hedging their bets. Also the author of the article does not feel it prudent to say all that is on his mind - and not just about nuclear energy.
2006 January note: The Hawaii Natural Energy Institute has a report on hydrogen. Useful appendices compare technologies and their costs for various ways of producing and using hydrogen. As is still common in the energy studies business, nuclear energy is ignored. Nevertheless there is much useful information. I'm sure many of the authors of the study know better, but they also know mentioning nuclear is still not useful for getting funding from agencies beholden to the environmental movement. However, at long last, the environmentalists are beginning to wake up and argue about nuclear energy among themselves.
2007 March note: The 2007 April Scientific American has an article entitled "Hydrogen" by Sunita Satyapal, John Petrovic, and George Thomas of the U.S. DoE that seems the most realistic of any I have seen. It recognizes the main problem as the storage of enough hydrogen to give a car an adequate range. Their goal is the 300 mile range of present cars. They discuss compressed hydrogen, liquid hydrogen, and several new chemical systems. As for liquid, they report BMW's intention to sell the Hydrogen7 in Germany and in the U.S. in places where hydrogen stations can be built. The car will have 300 mile range on gasoline but a disappointing 125 miles on hydrogen.
The article cites goals for 2010 and 2015 that seem more adequate. These are based on chemical adsorbents.
Here's a link to a proposal to combine boron with water to get a hydrogen fuel. I don't know how long the link will last.
My goal for this page is to put in more numbers, e.g. the number of joules per kilogram of hydrogen required by electrolysis and also references to the literature on the production and use of hydrogen. I solicit information and references.
Here's a link to Magna Steyr, the manufacturer of the liquid hydrogen tank for the BMW 745h.Here's a start on the numbers. Table A.59 (of _Handbook_of_Physical_Calculations_, J. J. Tuma, McGraw-Hill New York, 1967 ISBN 0-07-065438-7) titled "Average Heat of Combustion" lists "Gasoline(0.71) 11.50; Gasoline(0.77) 11.90; Hydrogen 33.90" with units 1E3_kcal/kg in each case.
The Scientific American article cited above lists 50 kw as the peak performance required for a car. That's less than what good performance cars give, but probably about right for economy cars.
This article doesn't claim to have shown that powering cars with liquid hydrogen produced by nuclear reactors is the best solution. I do claim that it is an adequate solution, and our descendants 100 years or 10,000 years from now will have automobiles if they want them.
Send comments to mccarthy@stanford.edu. I sometimes make changes suggested in them. - John McCarthyThe number of hits on this page since 1995 December 31.

Question: what would be used in nuclear fusion plants

Water is not a source of energy, except in possible nuclear fusion power plants, which would use deutery and tricium, which is still far from commercial use.

what would be used in nuclear fusion plants

Question: what is the main source of energy in vodik

what is the main source of energy in vodik

Question: what is the function of water in vodik

Question: how do we get energy from solar, biological or electric sources

how do we get energy from solar, biological or electric sources

Question: what type of metal is used in nuclear fusion

what type of metal is used in nuclear fusion

Question: where is water used as a source of energy

elektranama na nuklearnu fuziju , koje bi koristile deuterij i tricij , što je još daleko od komercijalne upotrebe

where is water used as a source of energy

Question: what type of material would be used in nuclear fusion

what type of material would be used in nuclear fusion

Water is not a source of energy , except in possible nuclear fusion power plants , which would use deutery and tricium , which is still far from commercial use .

Water obtained from solar , biological or electric sources requires more energy than we can get from it by combustion , so it has more role as a battery , for preparation or storage of energy .

Vodik nije izvor energije, osim u mogućim elektranama na nuklearnu fuziju, koje bi koristile deuterij i tricij, što je još daleko od komercijalne upotrebe.

Water is not a source of energy, except in possible nuclear fusion power plants, which would use deutery and tricium, which is still far from commercial use. Water obtained from solar, biological or electric sources requires more energy than we can get from it by combustion, so it has more role as a battery, for preparation or storage of energy.

Water is not a source of energy, except in possible nuclear fusion power plants, which would use deutery and tricium, which is still far from commercial use.

The energy density per unit of volume, for liquid or compressed hydrogen, is much lower than the known fossil fuels, although by unit of mass, the energy density is greater.

Question: what is the energy density of liquid hydrogen compared to fossil fuels

what is the energy density of liquid hydrogen compared to fossil fuels

Question: is the energy density of liquid hydrogen greater or lower than fossil fuels

is the energy density of liquid hydrogen greater or lower than fossil fuels

Question: is the energy density of liquid hydrogen higher or lower than fossil fuels

is the energy density of liquid hydrogen higher or lower than fossil fuels

Question: what is the difference between fossil fuels and vodik

what is the difference between fossil fuels and vodik

Question: the energy density of liquid hydrogen is lower than that of

fosilnih goriva , iako po jedinici mase , gustoća energije je veća

the energy density of liquid hydrogen is lower than that of

Question: what does vodik measure in unit of mass

energije po jedinici obujma , za tekući ili komprimirani vodik , je puno manja od poznatih fosilnih goriva , iako po jedinici mase , gustoća energije je veća

Question: what types of fuels are used in vodik

tekući ili komprimirani vodik , je puno manja od poznatih fosilnih goriva , iako po jedinici mase , gustoća energije je veća

The energy density per unit of volume , for liquid or compressed hydrogen , is much lower than the known fossil fuels , although by unit of mass , the energy density is greater .

Gustoća energije po jedinici obujma, za tekući ili komprimirani vodik, je puno manja od poznatih fosilnih goriva, iako po jedinici mase, gustoća energije je veća.

Gustoća energije po jedinici obujma, za tekući ili komprimirani vodik, je puno manja od poznatih fosilnih goriva, iako po jedinici mase, gustoća energije je veća.

Separation of water into protons, electrons and oxygen, occurs in almost all plants that do photosynthesis.

Question: which type of algae has a second step after dark

modrozelene alge su razvile i drugi korak , po mraku , kojim se stvara plinoviti

Separation of water into protons, electrons and oxygen, occurs in almost all plants that do photosynthesis.

which type of algae has a second step after dark

Question: where do blue green algae get their h2 from

where do blue green algae get their h2 from

Question: what is the first step of the vodik cycle

what is the first step of the vodik cycle

Question: where does the water come from in vodik

Question: what is the name of the second step in vodik

what is the name of the second step in vodik

Question: where does the gas hydrogen h2 come from

where does the gas hydrogen h2 come from

Question: what is the first step in the vodik cycle

what is the first step in the vodik cycle

Separation of water into protons , electrons and oxygen , occurs in almost all plants that do photosynthesis .

Some such organisms , such as blue - green algae , have developed a second step , after the dark , by creating gas hydrogen H2 with the help of special hydrogenates in chloroplast .

Razdvajanje vode u protone, elektrone i kisik, javlja se kod gotovo svih biljaka koje vrše fotosintezu.

Neki takvi organizmi, kao modrozelene alge su razvile i drugi korak, po mraku, kojim se stvara plinoviti vodik H2 uz pomoć specijalnih hidrogenaza u kloroplastu.

Separation of water into protons, electrons and oxygen, occurs in almost all plants that do photosynthesis. Some such organisms, such as blue-green algae, have developed a second step, after the dark, by creating gas hydrogen H2 with the help of special hydrogenates in chloroplast.

Separation of water into protons, electrons and oxygen, occurs in almost all plants that do photosynthesis.

Safety and warning measures Water creates a whole series of dangers for human safety, especially H2 is empty as a gas breaker in the air.

Question: which gas is used as a gas breaker in vodik

Safety and warning measures Water creates a whole series of dangers for human safety, especially H2 is empty as a gas breaker in the air.

which gas is used as a gas breaker in vodik

Question: what is the main source of danger in vodik

what is the main source of danger in vodik

Question: what is the purpose of h2 in vodik

Question: why is h2 empty in vodik

Question: what is the danger of water in vodik

Question: what is the purpose of vodik in water safety

what is the purpose of vodik in water safety

Safety and warning measures Water creates a whole series of dangers for human safety , especially H2 is empty as a gas breaker in the air .

Sigurnost i mjere opreza Vodik stvara čitav niz opasnosti za čovjekovu sigurnost, pogotovo H2 je opasan kao plin praskavac u zraku.

Sigurnost i mjere opreza Vodik stvara čitav niz opasnosti za čovjekovu sigurnost, pogotovo H2 je opasan kao plin praskavac u zraku.

Safety and warning measures Water creates a whole series of dangers for human safety, especially H2 is empty as a gas breaker in the air.

Safety and warning measures Water creates a whole series of dangers for human safety, especially H2 is empty as a gas breaker in the air.

External links Water (PSE) - Faculty of Chemistry and Technology Split

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Vodik je 1766. godine otkrio Sir Henry Cavendish (Engleska). Ime mu je dao Lavoisie od grčkih riječi hydro što znači voda i genes što znači tvoriti. To je plin bez boje i mirisa, netopljiv u vodi. Lako difundira kroz sve materijale. Zapaljiv je i pravi eksplozivne smjese u zraku. Zapaljen na zraku gori svijetlim vrućim plamenom dajući vodenu paru. Na povišenoj temperaturi lako se spaja s kisikom, sumporom i halogenim elementima.
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Procjenjuje se da 90% svih atoma, odnosno skoro 3/4 mase svemira, otpada na vodik. Sve zvijezde, pa i Sunce, sastavljene su uglavnom od vodika (w > 90%). Vodik se u prirodi rijetko nalazi u elementarnom stanju, samo u višim slojevima atmosfere ili u vulkanskim plinovima. Uglavnom je vezan u spojevima od kojih su najrašireniji voda (H2O), amonijak (NH3) i razni organski spojevi. Čisti vodik se najčešće dobiva elektrolizom vode. Laboratorijski se dobiva reakcijom sulfatne kiseline i elementarnog cinka. Industrijski se dobiva prevođenjem vodene pare preko užarenog koksa. Upotrebljava se za sintezu amonijaka, hidriranje ugljena i ulja, proizvodnju kloridne kiseline i kao redukcijsko sredstvo. Cijena plinovitog vodika čistoće 99.999% iznosi 200.70 €/dm3 u malim pakovanjima (1 dm3) i oko 2.21 €/dm3 u velikom pakovanju (300 dm3).
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Question: what does pse stand for in vodik

External links Water (PSE) - Faculty of Chemistry and Technology Split

Question: what is the faculty of vodik university

Question: vodik is an abbreviation for which discipline

vodik is an abbreviation for which discipline

Question: what is the meaning of vodik in chemistry

what is the meaning of vodik in chemistry

Question: vodik is an abbreviation for what

Question: vodik is an abbreviation for department of chemistry in

vodik is an abbreviation for department of chemistry in

External links Water ( PSE ) - Faculty of Chemistry and Technology Split

Vanjske poveznice Vodik (PSE) - Kemijsko-tehnološki fakultet Split

Vanjske poveznice Vodik (PSE) - Kemijsko-tehnološki fakultet Split

External links Water (PSE) - Faculty of Chemistry and Technology Split

External links Water (PSE) - Faculty of Chemistry and Technology Split


Povijest
Helij (grč. ἥλιος = Sunce), otkrio je Pierre Janssen 1868. godine, kada je tijekom potpune pomrčine Sunca spektografskim isptivanjem kromosfere, gdje ga ima u velikim količinama, otkrio posebnu emisijsku liniju. Iste godine Lockyer je u žutom dijelu spektra, između dvije natrijeve, otkrio novu liniju. Smatravši da pripada novom elementu, dao mu je ime helij.

U laboratoriju je dobiven 1895. godine zagrijavanjem klevita, minerala koji sadrži uranij.

 Svojstva
Helij je na običnoj temperaturi plin bez boje, mirisa i okusa, u načelu kemijski gotovo potpuno neutralan, od svih plinova najteže ukapljiv. Poslije vodika, najlakši je plin. Iako atom helija ima četiri puta veću masu od atoma vodika, gustoća mu je samo dva puta veća jer se atomi helija, kao i ostalih plemenitih plinova, ne vezuju u molekule. Uz iste uvjete, u nekom određenom obujmu plemeniti plin ima dva puta manje atoma od drugih plinova.
Tekući helij ima najniže vrelište od svih elemenata, a pri standardnom tlaku nema talište, već je, da bi se skrutio, potrebno tlačiti ga.

 Rasprostranjenost
Nakon inicijalnih otkrića, pronađen je i u zraku (0,00007%), a prema spektru polarne svjetlosti pronađeno je da se najviši slojevi Zemljine atmosfere sastoje uglavnom od vodika i helija. Obilniji izvori su mu plinovi iznad naftnih slojeva, odakle se i crpi, a ima ga i u mineralnim izvorima.

U svemiru je drugi najrasprostranjeniji element, masenog udjela 23%. Većina helija nastala je netom nakon Velikog praska u nukleosintezi. U zvijezdama nastaje nuklearnom fuzijom vodika te ciklusom ugljik-dušik-kisik.

Većina helija na Zemlji posljedica je uhvata elektrona od strane alfa-čestice nastale radioaktivnim raspadom. Na taj način godišnje nastane oko 3000 tona helija u cijeloj litosferi. Stalna koncentracija helija u zraku proizlazi iz činjenice da postoji ravnoteža između količine helija koja izlazi iz tla i količine koja struji u svemir. Proračuni su pokazali da bi radioaktivni raspadi trebali dati više helija, no nesrazmjer u proračunu i očitanoj vrijednosti objašnjen je time što se helij iz ekstremnih dubina ne može probiti do površine.

Helija ima u mineralima radioaktivnih elemenata (klevit, monacit, torianit i drugi), a i u berilu. Ima ga slabo otopljenog u mineralnim vodama, od kojih ga neke sadrže do 0.1% (Islandski gejziri).

 Dobivanje

Najveći dio dobiva se iz zemnog plina, a puno manji dio ukapljivanjem i frakcijskom destilacijom tekućeg zraka ili zagrijavanjem minerala koji ga sadrže, iznad 1000°C.
Kada se dobiva iz zemnog plina, prvo se čisti i ispire pomoću etanolamina i dietilen glikola. Zatim se suši aktivnim aluminijev oksidom, pri čemu se odstrane voda, ugljikov(IV) oksid i sumporovodik. Zemni plin zatim ulazi u izmjenjivač topline, gdje se uklanjaju prvo teži, a zatim sve lakši ugljikovodici. Rezultat je sirovi helij koji se sastoji od 70% helija, i 30% primjesa (dušik, argon, vodik i neon).
Ta smjesa plinova zatim se tlači na 17.3 MPa i tekućim dušikom hladi na -196°C. Svi plinovi, osim helija, ukaplje se, nakon čega se helij prevodi preko aktivnog ugljena. Dobiveni helij čistoće 99.997% ukapljuje se i skladišti u spremnicima.

 Spojevi
Helij je, osim u neuobičajenim uvjetima, potpuno inertan kemijski element. Podvrgnut električnom pražnjenju, moguće je dobiti vrlo male količine vrlo nestabilnih molekula s volframom, fluorom, sumporom i fosforom. Moguće je dobiti i molekulu helija s dva atoma, te molekulu HgHe, koja je izvanredno nestabilna jer se drži na okupu samo zbog polarizacijskih sila.
Teoretski mogući su spojevi s fluorom analogni spojevima fluora i argona, no još nisu sintetizirani.

Helij je moguće ubaciti u kaveze fulerenskih molekula, gdje se ne drže nikakvim silama. Unatoč tome, takvi "spojevi" pokazuju konkretan stehiometrijski sastav.

 Izotopi
Helij ima tri stabilna izotopa:

 He-3 s jednim neutronom, relativne atomske mase 3,01603
 He-4 s dva neutrona, relativne atomske mase 4,0026
 He-5 s tri neutrona, relativne atomske mase 5,0123

 Uporaba
Helij se koristi za punjenje zračnih brodova (cepelina) i rjeđe, za punjenje balona za meteoroška promatranja (češće se koristi vodik), jer nije lako zapaljiv kao vodik. Gustoća mu je dva puta veća od vodikove, tako da se baloni punjeni helijem sporije dižu, jer je i potisak takvih balona 7% manji nego kod onih punjenih vodikom. U tom cilju miješa se s 14% vodika. Koristi se svugdje gdje je potrebna inertna atmosfera, npr. kao mješavina u ronilačkim bocama, u specijalnim zavarivanjima u metalurgiji itd. Primjena u ronilačkim bocama je prvenstveno iz medicinskih razloga, tj. helij se lakše oslobađa iz organizma prilikom izranjanja nego recimo dušik, te pokazuje puno manji narkotički učinak.

Tekući se helij koristi za postizanje niske temperature, primjerice za hlađenje supravodljivih magneta u čestičnim ubrzivačima, MRI uređajima, kao i za punjenje plinskih termometara za niske temperature.

 Biološka uloga
Zbog svoje apsolutne inertnosti u standardnim uvjetima, helij nema biološku ulogu.

 Vanjske poveznice
Helij - KTF Split

Kategorija:Plemeniti plinovi

External connections Heli - KTF Split

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Helij su 1868. godine otkrili Pierre Jules César Janssen (Francuska) i Sir William Ramsay (Škotska). Ime mu dolazi od grčke riječi helios što znači sunce. To je plin bez boje i mirisa koji se u prirodi pojavljuje kao jednoatomni. Helij je kemijski inertan, nezapaljivi plin koji se ne spaja s drugim elementima.
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Prvi put pronađen je u spektru sunčevog zračenja. Helij je drugi elment, iza vodika, po rasprostranjenosti u cijelom svemiru. Nastaje raspadom radioaktivnih elemenata, a industrijski se proizvodi iz zemnog plina iz Teksasa (SAD) u kojem ga ima oko 2% (volumna). Upotrebljava se za punjenje balona, a smjesa koja se sastoji od 21% O2 i 79% He koristi se kao zamjena za zrak kod ronjenja na velikim dubinama. Cijena plinovitog helija čistoće 99.999% iznosi 177.10 €/dm3 u malim pakovanjima (1 dm3) i oko 2.52 €/dm3 u velikom pakovanju (300 dm3).
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Question: what is the meaning of heli in kTF

External connections Heli - KTF Split

Question: what is the acronym for the network of external connections

External connections Heli - KTF Split

Question: what is the name of the split between heli and kTF

External connections Heli - KTF Split

Question: what is the meaning of helij in kTF

External connections Heli - KTF Split

Question: what is the meaning of heli - kt split

External connections Heli - KTF Split

Question: what type of connections does heli have

External connections Heli - KTF Split

Question: heli is the acronym for which organization

External connections Heli - KTF Split

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External connections Heli - KTF Split


Povijest
Litij (grč. λιθoς = kamen) otkrio je Johan Arfwedson 1817. godine, a prvi ga je u elementarnom stanju izolirao William Thomas Brande, elektrolizirajući talinu litijevog oksida 1821. godine.

Brande je također sintetizirao čiste litijeve soli, te mu pronašao relativnu atomsku masu. 1855. godine Robert Bunsen i Augustus Matthiessen uspjeli su dobiti velike količine litija elektrolizom taline litijevog klorida. Komercijalnu proizvodnju, putem elektrolize smjese talina litijevog klorida i kalijevog klorida, počela je 1923. godine njemačka tvornica Metallgesellschaft AG.

Šulekov naziv za litij je litik.

 Svojstva
50px|mini|lijevo|Litijev plamen
Litij je najlakši od svih poznatih metala. Najmanje je reaktivan od svih alkalijskih metala. Također je najtvrđi i najvišeg tališta.

Teže se reže od natrija. Na svježem presjeku je srebrnasto bijel i reflektivan. Sa suhim zrakom reagira vrlo sporo, te dugo ostaje čist. Na običnom zraku nakon nekog vremena presvuče se hidroksidom i karbonatom.

Litij i njegovi spojevi plamen bojaju intenzivno crvenom bojom.

Upola je manje gustoće od vode, a pliva i u ugljikovodicima, stoga se čuva zaronjen ispod mineralnog ulja.

Posjeduje najveći specifični toplinski kapacitet od svih elemenata. Pri standardnom tlaku, postaje supravodljiv ispod 400 μK, a na neznatno višim temperaturama tek na tlakovima preko 200 tisuća atmosfera.

 Rasprostranjenost
Relativno je rijedak, no vrlo rasprostranjen.
Za razliku od ostalih alkalijskih metala, litij se u prirodi nalazi u obliku silikata i fosfata. Najveća ležišta rude litija su u Čile, Kanadi, Francuskoj, Njemačkoj i SAD.

 Dobivanje
mini|Litijeva baterija
Dobiva se iz ruda, prevođenjem u netopljivi karbonat, primjerice reakcijom samljevene rude s kalijevim sulfatom pri povišenoj temperaturi. Dobiveni produkt ekstrahira se vodom. Litijev sulfat se otapa, a karbonat se istaloži. Tretiranjem kloridnom kiselinom, karbonat prelazi u klorid, koji se suši, tali i elektrolizira.

 Spojevi
Litij gradi spojeve u kojima se nalazi u stupnju oksidacije +1, pa tako otapanjem u kiselinama daje jednovalentne soli.
Reakcijom s vodikom na povišenoj temperaturi, nastaje litijev hidrid koji lako reagira s vodom.

Litijev oksid moguće je dobiti samo reakcijom s čistim kisikom, a litijev nitrid reakcijom s dušikom.

Litijev hidroksid dobiva se polaganom reakcijom oksida s vodom:

Li2O(s) + H2 → 2 Li+ + 2 OH-

Poznata su sva četiri halogenida, od kojih je najvažniji klorid. Svi se litijevi halogenidi mogu sintetizirati izravnom reakcijom elemenata.

Ostale soli moguće je prirediti reakcijom metala, oksida, hidroksida ili karbonata reakcijom s kiselinom.

 Izotopi
Prirodni litij sastoji se od dva izotopa:
 Li-6 (7,4%)
 Li-7 (92,6%)

 Uporaba
Litij se koristi elementaran ili kao sol u organskim sintezama, metalurgiji i analitičkoj kemiji, mazivima i za suhe baterije koje mogu raditi na vrlo niskim temperaturama.
Litijev aluminat se koristi kao inertni elektrolitni potporni materijali u otopljenim karbonatnim gorivim člancima, gdje elektrolit može biti mješavina litijevog karbonata, kalijevog karbonata i natrijevog karbonata.

Njegovi izotopi 6Li i 7 korišteni su u proizvodnji litijeve bombe.

Malim dodatkom (<1%) litija poboljšavaju se mehaničke osobine aluminija i korozijska postojanost magnezija. Slitina litija i magnezija s malo srebra ima manju gustoću od vode, a veliku čvrstoću i antikorozijsku postojanost.

Litijevi spojevi koriste se u medicini kao psihofarmaci, primjerice za tretiranje bipolarnog poremećaja, gdje je aktivni sastojak litijev kation, Li+.

Stari Grci i Rimljani, moglo bi se reći, bili su među prvima koji su rabili metal litij kao psihoaktivni lijek. Ljudima s bipolarnim poremećajem preporučivali su konzumiranje mineralne vode. Sol litija u obliku tablete kod većine ljudi stišava cikličke izmjene maničnog i depresivnog ponašanja. Litij međutim izaziva drhtanje ruku, oslabljeno pamćenje, pojačanu žeđ i učestalo urniranje. Slabljenje pamćenja je jedan od glavnih razloga za prestanak uzimanja litija.Spencer A. Rathus: Temelji psihologije, Naklada Slap, 2000, Zagreb

 Biološka uloga

Bilješke

 Vanjske poveznice
Litij - KTF Split

Kategorija:Kemijski elementi

Biological Role Notes of External Links Lithium - KTF Split

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Litij je 1817. godine otkrio Johan August Arfvedson (Švedska). Ime su mu dali Arfvedson i Berzelius od grčke riječi lithos što znači stijena jer je litij otkriven u stijenama za razliku od druga dva elementa prve skupine, kalija i natrija, koji su dobiveni iz biljnog materijala. To je mekani, srebrno bijeli metal koji sporo reagira s kisikom iz zraka. Može se zapaliti na zraku, a u reakciji s vodom razvija vodik iako manje burno nego natrij. Litij je najjače redukcijsko sredstvo.
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Rijetko se nalazi u većim koncentracijama. Najčešće se javlja u obliku aluminosilikata kao što je spodumen (LiAlSi2O6). Litij je najlakši metal. Upotrebljava se za legiranje aluminija i za izradu specijalnih stakala i keramike. Zbog svog velikog elektrokemijskog potencijala koristi se kao anoda u baterijama. Cijena metalnog litija čistoće 99.95% iznosi oko 550 € za 1000 g.
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Question: which metal has the symbol kTF in its name

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Question: what does kt stand for in Litij

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Question: where does the term lithium come from

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Question: what is the meaning of the term Litij in english

Question: what is the meaning of Litij in english


Harfa je žičano glazbalo s tipično dvije do šest oktava, sa sedam žica po oktavi. Nađene su neke vrste u Africi, Europi, Aziji i Americi. Danas se koristi po cijelom svijetu iako nije popularna poput nekih drugih žičanih instrumenata. Harfa se ubraja među najstarija i najraširenija trzalačka glazbala. Ima trokutasti okvir unutar kojega je napet niz žica nejednake dužine (što uzrokuje različite tonske visine) i različite boje (radi lakšeg razabiranja velikog broja žica pri sviranju). Da bi se omogućio što veći broj žica harfa je kasnije izrađena iz dva komada drveta, koji se spajaju na krajevima, a ovaj model je poznat kao 'angle harp'.

Harfa se svira objema rukama, trzanjem žica vrhovima prstiju. Stoji na postolju na kojem je sedam pedala. Zvuk harfe je vrlo bogat i plemenit, ali nedovoljno velike snage i prodornosti, tako da najbolje dolazi do izražaja u solističkim nastupima ili solo izvedbama u orkestru. Jedino je glissandom i brzim prijenosom preko većeg broja žica moguće probiti gušći zvuk orkestra. Vrlo se često harfa može sresti kao pratnja nekom melodijskom instrumentu ili vokalu.

 Povijest
lijevo|140px|mini|Harfa
Harfa je vrlo staro glazbalo i pojavljuje se već u najdaljoj prapovijesti u mnogim dijelovima svijeta. Učestalo se pojavljuje u egipatskoj, grčkoj, židovskoj i keltskoj umjetnosti i književnosti, tijekom cijelog srednjeg vijeka.  Zajedničko obilježje harfi svih razdoblja njihov je okvir koji može tvoriti kut ili brid.Ilustrirana enciklopedija glazbe, glavni urednik: Paul Du Noyer, str. 438,

Današnja orkestralna harfa datira iz 19. stoljeća i predstavlja složenu (i vrlo skupu) inačicu osnovne harfe. Oblik harfe koji izgleda kao luk, koristi se i danas. Pošto su žice ugođene uvijek u jednom tonu (u današnje vrijeme to je Ces-dur), proširenje opsega oduvijek je predstavljalo veliki izazov. Prije nego što je izumljen pedalni sustav, intonacija se ugađala pomoću priručnih kvačica, što je bilo vrlo nespretno. Pedalni sustav izumljen je i usavršen u Bavarskoj i Francuskoj, a omogućuje podizanje intonacije za cijeli ili pola tona, i to na način da se mijenja intonacija svih istoimenih tonova u svim oktavama.

 Tehnika sviranja
Harfa se u pravilu svira svim prstima, osim malim prstom koji je uglavnom prekratak i slab da bi njime bilo moguće potezati žice. Većina oblika harfi zahtijeva samo korištenje ruku, dok se na nekim modelima koji imaju pedale koriste i noge.

Najčešća tehnika sviranja harfe je arpeggio (tonovi i akordi nižu se vrlo brzo jedan za drugim), te glissando (prelaženje rukama preko svih žica). Na harfi se može izvoditi jednako složena glazba kao i na glasoviru, iako se istodobno može odsvirati samo osam tonova jer se mali prsti ne koriste.

 Izvori

 Vanjske poveznice

Harp Spectrum - Osnovne informacije o harfi
Your harpist  - Informacije o harfi s punim dijagramom i dijelovi izdavača

Kategorija:Trzalačka glazbala

External Links Harp Spectrum - Basic Harp Information Your harpist - Full Diagram Harp Information and Publisher Parts

Everything the novice needs to know about the secrets of this mysterious instrument.
A look at the basic structure...
(Photo used by permission of Lyon & Healy. Visit their website by clicking HERE)
The harp is an ancient and widely distributed instrument, and its usage ranges from pure entertainment to solo and ensemble music. The oldest extant harp, found at Ur in Sumer, dates from ca. 2600 B.C.E. and was already an elegant and sophisticated instrument. Depictions of harps from the same period have been found in the Cyclades and in Egypt, where they existed in a variety of forms and sizes for nearly 2000 years.
It is presumed that the harp moved westward from Egypt in ancient times to Greece and Italy as early as the 6th century B.C.E. The harp first appears in medieval Europe in illuminated manuscripts and carvings from the 8th to 10th century. It was very popular in Ireland, beginning in the 10th century, where it became the country's national symbol. The Irish harp has a sound box carved from a single piece of wood, a pillar that curves outward, and 30 to 36 metal strings that can be played with either the fingers or the finger nails.
Our modern orchestral harp has 47 strings and evolved through a series of formats which attempted to solve the problem of chromaticism. The final version, a "double action" harp, was patented in 1810 by Sebastian Erard of Paris and enabled the performer to alternate the pitch of each string between flat, natural, and sharp by moving a pedal between three individual positions (see illustration).
Diagram from HARPS &
HARPISTS by Roslyn Rensch, reproduced by permission of Gerald Duckworth
& Co Ltd. Harps and Harpists is available from Indiana University Press.
The pedals are organized in the following order, and are easily remembered by the phrase "DidColumbus Bring Enough Food Going (to) America."
Diagram from HARPS & HARPISTS by Roslyn Rensch, reproduced by permission of Gerald Duckworth & Co Ltd. Harps and Harpists is available from Indiana University Press.
The strings are lengthened and shortened (thus changing the pitch) by a complex mechanism which runs from the pedals up through the column and into the neck. There are two forked disks for each note on the outside plate that twist against the string when deployed. For example, when a pedal is moved from flat to natural, the top disk turns and pulls the note up a half-step. When the pedal is moved again from natural to sharp the note raises a second time.
Diagram from HARPS &
HARPISTS by Roslyn Rensch, reproduced by permission of Gerald Duckworth
& Co Ltd. Harps and Harpists is available from Indiana University Press.
Facts worth knowing...
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