Reactivity Series of Metals
When elements are placed in order of their chemical reactivity the sequence is known as an activity series. It is normally used only for metals, together with the non-metals carbon and hydrogen. The list is arrived at by comparing the reactions of these metals with oxygen, with water, and with dilute acid. The activity series is in fact a list of metals in order of the ease with which they form ions. The activity series is more commonly known as the reactivity series.
The list of elements in order of their ability to lose electron (i.e. in order of their standard electrode potentials) is sometimes called the electrochemical series (E.C.S.). It is virtually the same as the reactivity series except it can be extended to include many other substances rather than just the metals, carbon and hydrogen. The hydrogen electrode is just one example of the way non-metals that are neither solids nor conductors can be included in the E.C.S.
Calcium is included in the reactivity series but not in the E.C.S. This is because the electrode potential of calcium is not quite as expected from its chemical reactivity. Also, the value given for Aluminium in the E.C.S. is for that value when its oxide layer has been removed. In practice or reality it is often less reactive than zinc or iron.
Reaction of metals with Oxygen
When metals are heated in air, if they react at all they usually react with the oxygen to form oxides. Some metals burn "completely" to form a high yield of their oxides but others react briefly to become coated with a layer of oxide which stops further reaction with the metal e.g. aluminium.
When elements are placed in order of their chemical reactivity the sequence is known as an activity series. It is normally used only for metals, together with the non-metals carbon and hydrogen. The list is arrived at by comparing the reactions of these metals with oxygen, with water, and with dilute acid. The activity series is in fact a list of metals in order of the ease with which they form ions. The activity series is more commonly known as the reactivity series.
The list of elements in order of their ability to lose electron (i.e. in order of their standard electrode potentials) is sometimes called the electrochemical series (E.C.S.). It is virtually the same as the reactivity series except it can be extended to include many other substances rather than just the metals, carbon and hydrogen. The hydrogen electrode is just one example of the way non-metals that are neither solids nor conductors can be included in the E.C.S.
Calcium is included in the reactivity series but not in the E.C.S. This is because the electrode potential of calcium is not quite as expected from its chemical reactivity. Also, the value given for Aluminium in the E.C.S. is for that value when its oxide layer has been removed. In practice or reality it is often less reactive than zinc or iron.
Reaction of metals with Oxygen
When metals are heated in air, if they react at all they usually react with the oxygen to form oxides. Some metals burn "completely" to form a high yield of their oxides but others react briefly to become coated with a layer of oxide which stops further reaction with the metal e.g. aluminium.
