Question

What do you understand by the reactivity series of the metal? Write the name of one metal each which is more reactive and less reactive than hydrogen.

Answer 1

Hint: Reactivity series refer to the metal series in which metals are arranged according to their reactivity from highest to lowest. It is also known as activity series which is used to predict whether a metal can displace another metal in a displacement reaction or not. This is a series in descending order of the reactivity of metals.

Complete step by step answer:
This series is quite helpful as it gives us information about the reaction of metals with acids, other metals, compounds, water, etc. As we approach the reactivity series from bottom to top we will find an increase in reactivity, corrosion of metals increases, metals become stronger reducing agents i.e. stronger electron donors.
Sodium is more reactive than hydrogen. Few reactions of sodium are-
$Na+{{H}_{2}}O\to NaOH+\dfrac{1}{2}{{H}_{2}}+33.67\,kcal\,per\,mole\,at\,{{25}^{0}}C$
Sodium reacts with water to form a strong base which is sodium hydroxide.
$Na + N{{H}_{3}}\to Na N{{H}_{2}}+\dfrac{1}{2}{{H}_{2}}$
Copper is less reactive than hydrogen. Copper belongs to the gold family which has high thermal and electrical conductivity. The displacement reaction is the one in which metal of higher reactivity displaces metal of lower reactivity.
$Mg + Cu S {{O}_{4}}\to Mg S{{O}_{4}}+Cu$
In the above reaction magnesium displaces copper metal to form magnesium sulfate because magnesium is more reactive than copper. One can see from the series that magnesium is placed above copper due to which it has higher reactivity than copper.

Note:
The tendency to lose electrons and form positive ions is more for higher reactive metals. High reactivity metal needs a high amount of energy for isolation from their ores and other compounds. It provides us information about how the metal reacts. Physical properties can also affect the reactivity of pure compounds like grinding the sample leads to increase in reactivity.