1. Counting Atoms
Vocabulary and Steps

2. Chemical Symbol
Usually a one- or two-letter set of characters that is used to identify an element.
Examples: H, He, Ne, W, Li, Ag

3. Compound Formula
A combination of symbols that shows the ratio of elements in a compound.
Example: H2O (two hydrogen : one oxygen)

4. Subscript
Shows the number of atoms of an element in a molecule or the ratio of elements in a compound.
No subscript means one.
Example: H2O
The two is the subscript for hydrogen so there are two hydrogens
Oxygen has no subscript so there is one oxygen

5. Coefficient or Pre-Script
A number placed in front of a chemical formula in an equation.
No coefficient means one.
Example: 6CO2
Six is coefficient, it is used for all the elements of the compound or molecule.
There are six carbons and twelve oxygens in the formula above.

6. Counting ‘em Up!!
If there is a subscript, but no coefficient use the subscript for the element.
H2O (2 hydrogen, 1 oxygen)
If there is a coefficient, but no subscript use the coefficient for every element .
2AgS (2 silver, 2 sulfur)
If there is a subscript and a coefficient multiply the coefficient by the subscript for each element.
12CO2 (12 carbon, 24 oxygen)