2.  Anything that has mass and takes up space  Made up of tiny particles called atoms  Atoms: smallest particle of matter

3.  Smallest unit of an element that maintains the properties of that element  Can not be broken down into anything smaller  Scientists used to think they couldn’t be split, but we now know that was incorrect

4.  The physical forms of matter, which include solid, liquid, and gas

5.  The state of matter in which the volume and shape of a substance are fixed  Definite shape  Definite volume  Particles are tightly packed  Particles barely move  They vibrate in place

6.  The state of matter that has a definite volume but not a definite shape  No definite shape  Definite volume  Particles move fast enough to separate a little  Allowing them to change shape  Particles do not move fast enough to change volume

7.  Viscosity: a liquid’s resistance to flow  High Viscosity: Slow Flow (Honey)  Low Viscosity: Fast Flow (Water)  Surface Tension: force that attracts the molecules at the surface of a liquid to form the drop

8.  The state of matter that does not have a definite shape or volume  No definite shape  No definite volume  Particles move so fast that they completely separate from each other  Allowing them to change shape and volume

9.  Change of a substance from one physical form to another  Requires adding or removing energy so that particles can speed up or slow down

10.  Change of state when a solid becomes a liquid  Particles must speed up  Add energy/heat  Endothermic  Melting Point: Temperature at which a substance melts  Water: 32°F or 0°C

11.  Change of state from a liquid to a solid  Particles must slow down  Remove energy/heat  Exothermic  Freezing Point: Temperature at which a substance freezes  Water: 32°F or 0°C

12.  Change of a liquid to a gas (throughout an entire liquid)  Particles (on bottom of liquid) must speed up  Add energy/heat  Endothermic  Boiling Point: Temperature at which a substance boils  Water: 212°F or 100°C  At Sea Level: Boiling depends on Air Pressure **Won’t happen unless air pressure equals pressure in bubbles

13.  Change of a substance from a liquid to a gas (only on surface)  Particles (on surface) must speed up  Add energy/heat  Endothermic

14.  Change of state from a gas to a liquid  Particles must slow down  Remove energy/heat  Exothermic

15.  Change of state from a solid to a gas  Example: Dry Ice  Skips liquid stage  Add energy/heat  Endothermic