how many valence electrons does the ammonium ion have?
Let's do the Lewis structure for NH4+, the ammonium ion. So Nitrogen, on the periodic table, is in group 5, so it has 5 valence electrons. Hydrogen, group 1; we've got 4 of these, though; four Hydrogens, so let's multiply that times 4. And if you see a plus sign, that means you've lost a valence electron.