1. Chemistry Vocabulary: Part 4

2. Chemical Formulas
A combination of chemical symbols and numbers to represent a substance
Examples
H20: Water
CO2: Carbon Dioxide
NaCl: Salt
C6H1206: Sugar

3. Chemical Equations
A representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products
Examples
C O2  CO2
2H2 + O2  2H2O

4. Reactants
A substance or molecule that participates in a chemical reaction
Examples
C O2  CO2
Reactants
2H2 + O2  2H2O

5. Products A substance that forms in a chemical reaction Examples
C O2  CO2
Product
Zn + 2HCl  ZnCl2 + H2

6. Subscripts
A number written below and to the right of a chemical symbol in a formula
Tells how many atoms of that element are present
Examples
CO2
H20
C6H12O6

7. Coefficients
A number that is placed in front of a chemical symbol or formula
Tells how many molecules of that substance are present
Keeps reaction balanced
Example
2H2 + O2  2H2O

8. Law of Conservation of Mass
Mass is neither created nor destroyed in ordinary chemical and physical changes
Must start and end with the same amount
Example
Log Fire  Ashes Smoke
30 kg kg kg kg