Question

what is meant by reactive series of metals?give the position of major metals in the reactivity series

Answer 1

the arrangement of the metals in decreasing order of their chemical reactivity is called metal reactivity series.
potassium
sodium
calcium
magnesium
aluminium
zinc
iron
lead
(hydrogen )
copper
mercury
silver
gold
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Answer 2

In chemistry, a reactivity series (or activity series) is an empirical, calculated, and structurally analytical progression of a series of metals, arranged by their "reactivity" from highest to lowest. It is used to summarize information about the reactions of metals with acids and water, double displacement reactions and the extraction of metals from their ores.The reactivity series is sometimes quoted in the strict reverse order of standard electrode potentials, when it is also known as the "electrochemical series":Li > Cs > Rb > K > Ba > Sr > Ca > Na > Mg > Be > Al > H(in water) > Mn > Zn > Cr(+3) > Fe(+2) > Cd > Co > Ni > Sn > Pb > H(in acids) > Cu > Fe(+3) > Hg > Ag > Pd > Ir > Pt(+2) > Au > Pt(+4)

The positions of lithium and sodium are changed on such a series; gold and platinum are in joint position and not gold leading, although this has little practical significance as both metals are highly unreactive.

Standard electrode potentials offer a quantitative measure of the power of a reducing agent, rather than the qualitative considerations of other reactive series. However, they are only valid for standard conditions: in particular, they only apply to reactions in aqueous solution. Even with this proviso, the electrode potentials of lithium and sodium – and hence their positions in the electrochemical series – appear anomalous. The order of reactivity, as shown by the vigour of the reaction with water or the speed at which the metal surface tarnishes in air, appears to be

potassium > sodium > lithium > alkaline earth metals,

the same as the reverse order of the (gas-phase) ionization energies. This is borne out by the extraction of metallic lithium by the electrolysis of a eutectic mixture of lithium chlorideand potassium chloride: lithium metal is formed at the cathode, not potassium.