Question

Name two metals which are soft.

Answer 1

Hint: The hardness and softness are the physical properties of an element which is a result of the type of bonding present in them.
- The valence electrons present in an element have a greater influence in the crystal lattice formation.

Complete step by step answer:
- In the question, it is asked that we have to name two metals that are soft. That question itself is quite awkward as from the class we start studying about elements, metals, non-metals ,we have heard that the metals are strong hard substances, And the metals which we see in our day to day life is typically very hard and strong substance.
The question is about the exceptions cases in the metal category.
- Though we know this question is a factual type question, let’s approach the question in a different way.
We know that the softness and hardness are the physical properties of the elements and these physical properties shown by the elements are due to the different types of bonds present in them, the arrangement of the atoms in the lattice, the number of valence electrons present etc.
- Since the question is about the metals, we know that the bonding in metals is metallic bonding.
- The metallic bonding can be defined as the bond formed by the sharing of the valence electrons with a sea of positively charged electrons. The metallic bonding is formed due to the attraction between the positive charged ions and the delocalized electrons when the atoms are arranged together. Metallic bond accounts for the physical properties like hardness and softness of the elements.
- The metallic bonding depends on many factors and some are-the size of the cation, the total delocalized valence electrons, magnitude of the charge possessed by the positively charged ion.
The lesser the number of delocalized valence electrons, the lesser the magnitude of the charge weaker will be the metallic bonding.
- In that case when we compare the elements in the periodic table, the metals are placed on the extreme left side of the periodic table.
- And if we compare group 1 and group 2, alkali metals will possess the weak metallic bond since they have less number of delocalized valence electrons and the charge carried by the alkali metals is lesser than the alkaline earth metals.
- Hence the group-1 elements will be soft in nature.
- Therefore two metals that are soft in nature are Na which can be cut with a knife and Cs which is the softest in the group.

Note: The soft metals possess low melting point since the intermolecular force between the atoms are very weak and while heating, the structure collapses and loses their rigid crystalline nature. Hence the alkali metals will be having low melting point.