Unit D Chapter 3 Vocabulary
1. Chemical Reaction – the process by which chemical
changes occur. Chemical bonds are broken, atoms rearrange
themselves, and new bonds are formed.
Ex. CH4 + 2O2  2H2O + CO2
2. Reactant – substance(s) present at the beginning of a
chemical reaction. Ex. CH4 + O2 is burning natural gas.
3. Product – the result of a chemical reaction. Ex. H2O + CO2
after burning natural gas.
4. Precipitate – a solid product formed when two liquids react.
Ex. Seashell.
5. Catalyst – a substance that changes another substance
quickly without changing itself.
6. Law of Conservation of Mass – in a chemical reaction,
atoms are neither created nor destroyed.
7. Coefficient – the number before a chemical formula that
indicates how many molecules are involved in a chemical
reaction. Ex. 2 O2
8. Concentration – amount of a substance contained in another
substance at a given temperature.
9. Bond Energy – the energy associated with bonds. Breaking
bonds requires energy and forming bonds releases energy.
10.
Exothermic Reaction – a reaction in which energy is
released.
11.
Endothermic Reaction – a reaction in which energy is
absorbed.
12.
Photosynthesis – plants absorb sunlight and turn it into
oxygen and glucose. Ex. H2O + CO2  C6H12O6 + O2
13.
Respiration – reverse of photosynthesis.
Ex. C6H12O6 + O2  H2O + CO2