Unit 3 Chemistry

chemical change

A change in matter that produces one or more new substances

chemical property

A characteristic of a substance that can only be observed during a chemical reaction.

reactants

The substance that enter into a chemical reaction

products

A substance formed as a result of a chemical reaction.

exothermic reaction

A reaction that releases energy in the form of heat (new substance feels warmer)

endothermic reaction

A reaction in which energy is absorbed (new substance feels colder)

closed system

A system in which no matter is allowed to enter or leave

precipitate

A solid that forms from a solution during a chemical reaction.

chemical bond

the force that holds two atoms together

valence electrons

Electrons on the outermost energy level of an atom

octet rule

States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons

Law of Conservation of Mass

the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes

oxidation

A chemical change in which a substance combines with oxygen, as when iron oxidizes, forming rust

flammable

A chemical property of matter

chemical reaction

the process by which one or more substances change to produce one or more different substances