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Reactivity of metals

Metal oxides

Most metals will react with oxygen to form oxides and some will react more easily than others. A good example of a metal that readily reacts with oxygen is iron. This forms iron oxide when it reacts with oxygen and more commonly referred to as rust. When a metal reacts in this way with oxygen it is called an oxidation reaction. Oxidation can however occur without reaction with oxygen and this will be described in more detail later.

The reactivity series

When metals react their atoms usually lose electrons to form positive ions. Their reactivity is based on their tendency to form positive ions. The atoms of group 1 metals lose one electron, the atoms of group II metals lose 2 electrons and the atoms of group III metals lose 3 electrons to form positive ions with charges of 1+, 2+ and 3+ respectively.  

The metals can be placed in order of reactivity where the order is based on how reactive the metals are when they react with water and acids. Below is a list showing the order of reactivity and is called the reactivity series:

Reactivity series

Element            Symbol


Potassium          K                        Most reactive

Sodium              Na

Lithium              Li

Calcium             Ca

Magnesium         Mg

Aluminium          Al

C arbon               C

Zinc                   Zn

Iron                    Fe

Tin                     Sn

Lead                   Pb

Hydrogen           H

Copper               Cu

Silver                 Ag

Gold                  Au

Platinum            Pt                         Least reactive

The metals are shown in order of decreasing reactivity starting from the top of the list. Two non-metals have been included in the list and are highlighted. These are carbon and hydrogen which are commonly used as reducing agents for extracting metals from their ores. Carbon is usually used to extract iron and can be used to extract any metal below carbon in the reactivity series.  

Exercise 1

1. State the type of reaction that occurs when a metal reacts with oxygen.

2. When metals react two changes occur. The following questions are based on these changes:

    a) What do metals lose when they react?

    b) How do the metal atoms change?

3. The following questions relate to the reactivity series:

    a) What is the reactivity series.

    b) Why are the non-metals carbon and hydrogen included in the reactivity series?

4. State if the following metals are more or less reactive than carbon.

    a) Ca

    b) Mg

    c) Fe

    d) Pb

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