Chemistry Vocabulary: Part 4

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

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

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

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

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

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

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 1 kg 28 kg 3 kg