CJHS Unit 4 Vocabulary

symbol(s)
One or two letters used to represent an element
chemical formula
A combination of symbols and numbers that
represent the number and types of elements
(atoms) present in a compound
subscript
A small number to the right of a symbol that is
written below the normal line of letters to show
how many atoms of an element are present in a
substance. No subscript means there is only one
atom present.
chemical reaction
When substances interact to form one or more
new substances with different properties than the
original substances
chemical equation
A combination of symbols and chemical formulas
used to describe what happens in a chemical
reaction. The equation identifies the reactants
and resulting products.
coefficient
A number written in front of a chemical formula to
show how many molecules of that substance are
present.
reactant
Formulas written on the left side of the arrow
symbol ( ) are the starting substances in a
chemical reaction.
product
Formulas written on the right side of the arrow
symbol ( ) are the new substances formed in a
chemical reaction.
yields
An arrow symbol that shows a reaction has taken
place. The reactants have reacted to produce a
new substance (the product).
compound
A substance composed of two or more elements
chemically combined and in a definite proportion
physical change
A change in which the characteristics of a
substance are only changed physically and the
chemical composition stays the same.
chemical change
A change in which a substance (or substances) is
changed into one or more new substances with
different properties than the original substances
law of conservation of
mass
Matter is not created or destroyed, only changed.
The number of atoms in the reactants must be
equal to the number of atoms in the product.
precipitate
A solid that forms as a result of a chemical
reaction. It may appear cloudy and will fall to the
bottom of the container over time.