States of Matter

A simple definition of matter is the “stuff” that takes up space and has mass.

Matter is made up of atoms. Atoms are made up of protons, neutrons and electrons. Atoms come together to form molecules which are the building blocks of every thing in the universe.

This table is made up of atoms.
Even you and your friends are made of atoms.

Most thing around you are made of atoms, millions and millions of atoms.

There are three basic states of matter matter: solids, liquids, and gases.


Solids refer to “stuff” that have a definite shape that does not conform to the container it is placed. The particles in a solid are tightly packed together and don’t move much.

These ice cubes are solid.


Liquids can flow. Its particles are loosely packed together and can move about. Liquid shape can change because it does not conform to the container it is placed.

Water is a liquid. It conforms easily to the container it is placed.


Gas has no fixed shape or volume. There is much space between the particles in a gas. The particles also have a lot of kinetic energy (energy in motion). This means the particles move around and may collide with each other. The particles then spread around and can fill a container. Within the container, the particles exert a force on the interior of the container. This force is called pressure.

The steam that comes out of a kettle is gas.
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Solid to Liquid and Back to Solid

Energy in the form of heat is the easiest way to help a solid change to a liquid.

Melting and Freezing

By now you should notice that matter can change from one state to another. The physical state of matter changes when energy is removed or added to the matter.

Adding thermal energy (heat) to a liquid water causes it to become steam or vapour. For water, the temperature needs to be a little over zero degrees Celsius to melt.

When heat is applied to a solid its particles vibrate faster and mover farther apart. When a certain combination of temperature and pressure is applied, the solid will melt and turn into a liquid. Thus for water, the temperature needs to be a little over zero degrees Celsius to melt.

Removing energy from liquid water causes it to change to ice.

However, if you put ice in a glass of water and leave it out at room temperature, the ice will eventually come to the same temperature. The ice will melt (fusion) from the heat coming from the water.

As heat is removed from a liquid, the particles slow down and settle into one location. The liquid will become a solid.

It is important to note that the freezing point of liquid to solid is zero degrees Celsius or 32 degrees Fahrenheit. The melting point of sugar, salt, and rock is higher than that of water.

When heat is applied to butter, it melts.

Sublimation and Vaporization

Sublimation occurs when a solid becomes a gas without gradually going through the process solid to liquid to gas.

Dry ice is a solid carbon dioxide. It will turn into a gas when left outside within 5 hours.

Vaporization occurs when a liquid becomes a gas through evaporation or boiling.

Condensation and Deposition

Condensation occurs when a gas loses energy and becomes a liquid.

Condensation of water forms clouds.
Condensation forms dew on grass in early morning.

Deposition occurs when a gas transforms directly into a solid.

Deposition works as sub-freezing air and water vapour changes to ice without becoming liquid. Frost is formed on the surfaces, such a window panes.

Dry ice is a solid form of carbon dioxide. The process when dry ice changes from a solid to a gas, without turning into a liquid, is called sublimation. The opposite process is called deposition, when carbon dioxide changes from a gas to solid (dry ice).

Video: Change of State

Video: Effects of Temperature and Pressure on Matter

Review Chemistry Terms and Phase Change

  1. Fusion/Melting – solid to liquid
  2. Freezing – liquid to solid
  3. Vaporization/Boiling – liquid to gas
  4. Condensation – gas to liquid
  5. Sublimation – solid to gas
  6. Deposition – gas to solid