Chemical Reactions of Period III Elements

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Chemical Reactions of Period III Elements

The table below summarises the most common oxides and chlorides of Period 3 elements.

Element Oxide Chloride
Na Na2O NaCl
Mg MgO MgCl2
Al Al2O3 AlCl3
Si SiO2 SiCl4
P P2O5 PCl3
S SO2 SCl2
Cl Cl2O Cl2


Most metallic elements, both metals and non-metals, combine directly with oxygen. Metallic elements form ionic oxides whilst non-metallic elements form covalently bonded oxides.

For example:

2Mg(s) + O2(g) → 2MgO(s)


There are a number of methods for preparing chlorides. The direct preparation can be used although the reaction can be vigorous.

For example:

2Al(s) + 3Cl2(g) → 2AlCl3(s)

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