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The three states of matter can be represented by the particle model. This model explains the properties of substances in their different states, as well as changes of state.

An ionic compound is made up of charged particles, called ions. It has a giant lattice structure with strong electrostatic forces of attraction.

A covalent bond is a shared pair of electrons. Covalent bonding forms molecules. Substances with small molecules have low melting and boiling points, and do not conduct electricity.

Giant covalent substances have many atoms joined together by covalent bonds. Diamond, graphite and graphene are forms of carbon with different giant covalent structures.

The structure of metals explains their high melting and boiling points and their conductivity. The properties of a metal can be modified by mixing it with another substance to form an alloy.

Nanoparticles are 1 nm to 100 nm in size. They have very large surface area to volume ratios. The properties of nanoparticulate substances are different from those of the same substance in bulk.

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