| Term | Definition |
| acid | substance with a pH lower than 7. |
| atom | the smallest particle of an element that
still retains the properties of the
element. |
| base | substance with a pH above 7. |
| compound | atoms of more than one type of element
that are chemically bonded together. |
| element | substance that is made of only one type
of atom. |
| heterogeneous mixture | a mixture which is not mixed evenly and
each component retains its own
properties. |
| homogeneous mixture | solid, liquid, or gas that contains two
or more substances blended evenly
throughout. |
| mixture | a combination of substances in which the
individual substances do not change or
combine chemically but instead retain
their own individual properties; can be
gases, solids, liquids, or any
combination of them. |
| pH | a measure of the concentration of
hydronium ions in a solution using a
scale ranging from 0 to 14, with 0 being
the most acidic and 14 being the most
basic. |
| pure substance | substances that are made of only one type of atom or only one type of molecule (a group of atoms bonded together). |
| salt | compound formed when negative ions from
an acid combine with positive ions from a
base. |
| solute | in a solution, the substance being
dissolved. |
| solution | a mixture which is evenly mixed
throughout; also known as a homogeneous
mixture. |
| solvent | in a solution, the substance in which the
solute is dissolved. |
| suspension | heterogeneous mixture containing a liquid
in which visible particles settle throughout. |
