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Metals have characteristic properties which make them very useful. These can be explained using appropriate models of metallic structure and bonding.

Metals can be arranged in order of reactivity by observing their reactions with water, acid and displacement reactions with other metal compounds. This determines how it is extracted from its ore.

Reactive metals are extracted from their ores using electrolysis. Ionic compounds conduct electricity when molten or in solution. Metal ions and non-metal ions are attracted to opposite electrodes.

A covalent bond is a shared pair of electrons. Covalent bonding results in the formation of molecules. Simple molecular substances have low melting and boiling points, and do not conduct electricity.

Crude oil is a finite resource. It can be separated into its useful fractions by fractional distillation. Some fractions undergo cracking to help meet demand for the smaller molecules.