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Science

Analysis of ionic compounds

Ionic compounds formed from ions. Ions are created when a metal loses electrons and a non-metal gains electrons. Ionic substances form giant ionic lattices [lattice: A lattice is a regular grid-like arrangement of atoms in a material. ] containing oppositely charged ions. They have high melting and boiling points, and conductconduct: To allow electricity, heat or other energy forms to pass through. electricity when melted or dissolved in water.

Ionic properties

Ionic bonds form when a metal reacts with a non-metal. Metals form positive ions; non-metals form negative ions. Ionic bonds are the electrostatic [electrostatic: An electrostatic force is generated by differences in electric charge (ie positive and negative) between two particles. It can also refer to electricity at rest. ] forces of attraction between oppositely charged ions.

Ionic lattice of sodium chloride, showing positively charged sodium ions bonded to negatively charged chloride ions

The oppositely charged ions are arranged in a regular way to form giant ionic lattices [lattice: A lattice is a regular grid-like arrangement of atoms in a material. ]. Ionic compounds [compound: A compound is a substance formed by the chemical union (involving bond formation) of two or more elements. ] often form crystals as a result. The illustration shows part of a sodium chloride (NaCl) ionic lattice.

Properties of ionic compounds

  • High melting and boiling points - Ionic bonds are very strong - a lot of energy is needed to break them. So ionic compounds have high melting and boiling points.
  • Conductive when liquid - Ions are charged particles, but ionic compounds can only conductconduct: To allow electricity, heat or other energy forms to pass through. electricity if their ions are free to move. Ionic compounds do not conduct electricity when they are solid - only when dissolved in water or melted.

Properties of ionic compounds

Ionic compoundProperties
Sodium chloride, NaCl

High melting point: 800ºC

Non-conductive in its solid state, but when dissolved in water or moltenmolten: Molten means reduced to liquid form by heating. It is mainly used to describe rock, glass or metal. NaCl will conduct electricity.

Magnesium oxide, MgO

Higher melting point than sodium chloride: around 2,800ºC. This is because its Mg2+ and O2- ions have a greater number of charges, so they form stronger ionic bonds than the Na+ and Cl- ions in sodium chloride.

Because magnesium oxide stays solid at such high temperatures, it remains non-conductive. It is used for high-temperature electrical insulation.

Back to Ionic compounds and analysis index

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