Account for the following:
(C) Zinc is a comparatively a soft metal, iron and chromium are typically hard
Metallic bonds are formed when charged ions share electrons and form a closely packed structure.
Weak metallic bonds result in softer metals like zinc, while stronger metallic bonds result in harder metals like chromium.
Cr (3d54s1) has five unpaired electrons in its d-orbitals .
- This allows it to use these electrons in metallic bonding, thus making stronger bonds.
Zn (3d104s2) has no unpaired electrons in its d-orbitals.
- Since the electrons are already paired, they are unable to participate in bonding.
- Hence, Zinc makes weaker bonds.
As a result of these weak metallic bonds in Zn and strong metallic bonds in Cr , Zn is soft whereas Cr is hard .