Thursday, September 9, 2010

Kinetic Model Theory

The states of Matter

There are five main states of matter. Solids, liquids, gases, plasmas, and Bose-Einstein condensates are all different states of matter. Each of these states is also known as a phase.

Elements and compounds can move from one phase to another phase when special physical forces are present. One example of those forces is temperature. The phase or state of matter can change when the temperature changes. Generally, as the temperature rises, matter moves to a more active state.



Phase describes a physical state of matter. The key word to notice is physical. Things only move from one phase to another by physical means. If energy is added (like increasing the temperature or increasing pressure) or if energy is taken away (like freezing something or decreasing pressure) you have created a physical change.



PROPERTY

SOLID

LIQUID

GAS

shape

fixed

same as container (indefinite)

same as container (indefinite)

volume

definite

definite

fills entire container (indefinite)

ability to flow

no

yes

yes

can be compressed

very slightly

very slightly

yes

volume change with heating

very small

small

large

Density

High

High

Low

















One compound or element can move from phase to phase, but still be the same substance. You can see water vapor over a boiling pot of water. That vapor (or gas) can condense and become a drop of water. If you put that drop in the freezer, it would become a solid. No matter what phase it was in, it was always water. It always had the same chemical properties. On the other hand, a chemical change would change the way the water acted, eventually making it not water, but something completely new


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