Water can take many forms. At low temperatures (below 0oC
), it is a solid. When at “normal” temperatures (between 0oC
and 100oC
), it is a liquid. While at temperatures above 100oC
, water is a gas (steam). The state that water is in depends on the temperature. Each state (solid, liquid, and gas) has its own unique physical properties.
Matter and Its States
Matter generally exists in one of three states: solid, liquid, or gas. The substance that the state exhibits is also a physical property. Some substances exist as gases at room temperature (oxygen and carbon dioxide), while others, such as water and mercury, exist as liquids. Most metals exist as solids at room temperature. All matter can exist in any of these three states.
Solid
A solid is defined by the following properties:
definite form (hard)
Absolute volume
Particles move around fixed axes.
If we cool liquid mercury to its freezing point -39oC.
, and under the right conditions of pressure, we will see that all the particles of the liquid will go into the solid state. Mercury can be solidified when its temperature is brought to the freezing point. However, when returned to room temperature conditions, mercury no longer exists in the solid state, and returns to its more common liquid form.
Liquid
Liquids have the following properties:
Has no definite shape (takes the shape of its container)
There is definite volume.
The particles are free to move over each other, but are still attracted to each other.
A familiar liquid is mercury metal. Mercury is an anomaly. It is the only metal we know of that is liquid at room temperature. Mercury also has the ability to stick to itself (surface tension) – a property that all liquids exhibit. Mercury’s surface tension is relatively high, which makes it very unique. Here you see mercury in its normal liquid form.
Gas
Gases have the following properties:
Has no definite shape (takes the shape of its container)
No definite volume.
Particles move randomly with little or no attraction to each other.
Highly compressible
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