Which element comes first in a chemical formula? ?

Question

Like if you have 4 Cl atoms and one C do you say Cl4C OR CCl4

what about 4 phosphorous and 10 oxgen?

2 iron, 3 sulfur?

how do you know?

Answer 1

CCl4 - http://en.wikipedia.org/wiki/Chemical_fo...

http://en.wikipedia.org/wiki/Hill_system

http://science.widener.edu/svb/pset/nome...

The Hill System explains to generally use it in alphabetical order. Except for cases when you have alcohol groups like OH.  More commonly, the outer atom in greater # follows the core atom in lesser #. Like these two:

P4O10

Fe2S3

You also need experience with writing these chemicals and naming them to know them by heart. P is positively charged and O is negatively charged. Negatively charged atoms in a compound follow positively charged atoms. Same for salts.