3577
For heavier metal ions such as Hg ( II ) and Pb ( II ) , because of their large zeta values which quench fluorescence , it is concluded that the fluorophore should be tethered to the metal - binding part of the sensor , and prevented from binding to the metal ion by steric and electronic factors .
 Chemical: Hg ( II ); Chemical: Pb ( II )
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: Hg ( II ); Chemical: Pb ( II )