Wikijunior:The Elements/States Of Matter
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[edit] The Three States of Matter
There are three main states of matter:
They are:
- Solids - Hold their shape rigidly
Examples: Blocks, dishes, chairs, pencils
- Liquids - Take the shape of their container, but are dense enough to be held together
Examples: Water, soda, milk, blood
- Gases - Take the shape of their container completely, in all dimensions
Examples: Air, oxygen, carbon dioxide, steam
Each state is also known as a phase. Elements can move from one phase to another phase when special physical forces are present. Notice the key word is physical. Things only move from one phase to another by physical means. If energy is added, for instance, increasing the temperature or increasing pressure, or if energy is taken away by freezing something or decreasing pressure, this is a physical change.
The are special names for when a substancemoves from one phase to another:
- Liquid to Gas - Evaporation or Boiling
Example: Boiling water (Liquid Water → Steam)
- Gas to Liquid - Condensation
Example: Water on the Side of a Soda Can (Water Vapor → Water Droplets)
- Solid to Liquid - Melting
Example: Melting Water (Ice → Liquid Water)
- Liquid to Solid - Freezing
Example: Freezing Water (Liquid Water → Ice)
- Solid to Gas - Sublimation
Example: Dry Ice Sublimation (Solid Carbon Dioxide "dry ice" → Carbon Dioxide Gas)
- Gas to Solid - Deposition
Example: Making Dry Ice (Gas Carbon Dioxide → Solid Carbon Dioxide "dry ice")
An 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. However, no matter what phase it is in, it is always water. It has the same chemical properties.
