III) Forms of Matter

A) States of Matter

1) Solid: Definite Shape and Volume

a) H2O: Atoms held tightly and vibrate in fixed position - This is ice.

2) Liquid: Definite Volume but no definite shape

a) H2O: Atoms not held close together however not in fixed positions and can flow – This is liquid water.

3) Gas: No Definite Shape or Volume

a) H2O: molecules are farther apart so they move freely - This is water vapor

B) Changes of State

1) Usually caused by adding or taking away heat

2) Melting point: Temperature at which a substance changes from a solid to liquid, or from a liquid to a solid, the freezing point.

a) The increase in thermal energy causes the atoms to vibrate faster and spread out

3) Boiling Point: Temperature at which a substance changes form liquid to a gas, or from a gas to liquid, condensation point.

a) The increase in energy (heat) causes the atoms to vibrate even faster and spread out even more

4) The stronger the attraction of the atoms ….

….. the more energy is needed to change from solid to liquid …

…therefore the substance will have a high melting point.

a) For example copper boils at 1083 C or 1981 F

5) Sublimation: A substance change directly from a solid to a gas

a) example frozen carbon dioxide, dry ice, turns directly to a gas w/o turning into a liquid first.

6) Pressure

a) Compressing a gas can turn it into a liquid

b) Reduce pressure and liquids boil at lower temperature

D) Plasma: a gas in which some of the atoms have lost their electrons.

a) Plasma has free electrons and positive ions (Over all Neutral)

b) Can conduct electricity

c) Stars are made of plasma c) Stars are made of plasma. Plasma is the most common form of matter in the universe.

d) Can be made by heating gas up to 2000 C or 3632 F

e) Occurs naturally on Earth as Lightning and Northern Lights, and the inner core of flames