Metals and non-metals
Francine Taylor-Campbell, Contributor

You should be able to:

• List the general, physical and chemical properties of metals.
• Describe the reactions of metals and their compounds.

Points to note

Students taking notes at Ascot High School. - Anthony Minott/Freelance Photographer

• Metals are generally found in groups 1, 2 and 3 of the periodic table.
• A metal describes an element that ionises by losing electrons and is referred to as being electropositive.
• Metals are reducing agents.
• Most metals react with dilute acids, water and steam. The oxides of metals are basic (except for Al, Zn and Pb) and react with acids to form salt and water.
• Metals exhibit the following physical properties: high melting and boiling points; good electrical and thermal conductivity; solids at room temperature (except for Hg) and easily bent or drawn into wires.
• The bonding in metals is responsible for their physical properties.

As stated earlier, metals undergo reactions with acids, oxygen, water and steam. The ease with which these reactions occur is dependent on the position of the metal in the reactivity series. This is a list of metals arranged in order of their reactivity or how readily they will lose their outer electrons. A metal that will readily give up its electrons (eg. K) is more reactive than one that loses electrons less readily (eg. Cu). Metals at the top of the series are the most electropositive and the ones at the bottom are the least electropositive.

The reactivity series of metals:

K Most reactive

Na

Ca Decreasing reactivity, ease of ionisation, stability of compounds and strength as reducing agents.

Mg

Al

Zn

Fe

Pb

(H)

Cu

Hg

Ag

Au

Least reactive

Summary of the reactions of metals

1. Metals react with air or oxygen to form oxides.

2Ca + O2 == 2CaO calcium oxide

Ag and Au have no reaction with oxygen.

2. Metals react with water or steam to form the oxide or hydroxide.

Na, K and Ca react with cold water to form the hydroxide and hydrogen.

2Na + 2H2O (l) == 2NaOH + H2

Metals above Pb react with steam to produce the oxide and hydrogen.

Mg + H2O (g) == MgO + H2

Below this, there is no reaction with water or steam.

3. With dilute acids, the metals higher up in the series react violently, forming salt and hydrogen. As you go down the list, the reaction is less vigorous, until you reach Pb, Cu, Ag and Au, which have no reaction.

4. The thermal stability of the nitrates, carbonates and hydroxides of metals is also based on the reactivity series. The ease with which these compounds decompose when heated increases as you go down the series. (See text for an outline of these reactions).

Francine Taylor-Campbell is an independent contributor.