Chapter 1 - Structure and bonding

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Chapter 1

When two elements react together they make a new substance called a compound. It is difficult to separate the elements after the reaction. Some atoms react by sharing electrons. We call this covalent bonding. Other atoms react by gaining or losing electrons. We call this ionic bonding. When atoms react in this way they get the electronic structure of a noble gas.

Formula of calcium oxide is CaO.

Formula of lithium oxide is LiO.

Formula of magnesium chloride is MgCl2.

When non-metal atoms react together they make covalent bonds. The atoms in these bonds are held together by shared electrons. Most substances held together by covalent bonds consist of molecules, but some have giant covalent structures sometimes called macromolecules.

Metals have giant structures. They are made up of metal atoms which are closely packed and arranged in regular patterns. There is evidence of this is the crystals we can sometimes see at the surface of a metal.

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