1. Notes 7.1& 7.2: Matter and Temperature

2. An element is defined as a pure substance that can’t be broken down into simpler substances by physical or chemical means.
Examples include: hydrogen, oxygen, gold, mercury.

3. An atom is the smallest particle of an element that retains the chemical identity of the element.
Atoms of different elements have different numbers of protons

4. A molecule is 2 or more atoms joined by a chemical bond
A compound is a substance made up of only 1 type of molecule. (Ex: water, propane, table salt)
A mixture contains more than 1 kind of atom, molecule or compound. (Ex: Pepsi)

5. Temperature is a physical property of matter.
There are 3 scales used: Fahrenheit, Celsius, and Kelvin.

6. Common thermometers use the expansion of a colored liquid to indicate an increase in temperature.
Other thermometers use other physical changes.

7. Temperature is a measure of the kinetic energy (motion) of individual atoms.
More motion = higher temp.
Less motion = lower temp.

8. Absolute zero – the lowest possible temperature.
Atoms stop moving; lowest energy.
Occurs at 0 Kelvin or
-273 degrees Celsius.

9. There are 4 phases or states of matter
Solid - holds its shape and doesn’t flow (atoms vibrate in place)
Liquid - holds its volume, but not its shape (atoms can move around each other- flow)
Gas - flows like a liquid, but doesn’t hold its volume -can expand or contract. (atoms are not bound to each other)
Plasma - A gas where the electrons have broken loose from the atom. (formed in stars and lightning bolts)

10. Changing phases:
Changes in states of matter require energy.
There is NO temperature change during a change of phase.