1. Compounds & Formulas

2. Compounds
There are about 100 million pure substances that have been identified
Out of these pure substances, only 118 of them are elements, the rest are compounds
Compounds are made up of more than one element that is held together by a chemical bond
Every compound is made up of a chemical formula

3. Chemical Formulas A chemical formula tells us:
A) the type of atoms present
B) the number of atoms present
C) the type of compound

4. Reading Chemical Formulas
E.g. table salt: Sodium Chloride
Chemical formula NaCl
Count the atoms present
1 Na atom
1 Cl atom

5. Reading Chemical Formulas
Sometimes there are subscripts present.
A subscript is a small number that is in a chemical formula
E.g. water: H2O
2 H atoms
1 O atom
Subscript

6. Reading Chemical Formulas
Sometimes there are brackets with a subscript.
E.g. calcium hydroxide (kidney stones)
Ca(OH)2
1 Ca atom
2 O atoms
2 H atoms

7. Reading Chemical Formulas
Sometimes there are subscripts in the brackets.
E.g. calcium nitrate
Ca(NO3)2
1 Ca atom
2 N atoms
6 O atoms (3 oxygens x 2 = 6)

8. Assignment How to Count Atoms Review Counting Atoms Worksheet
Subscripts and Coefficients
Chemical Bonding definitions