Question

According to the definition, the element (Hg) (Mercury) belonging to the ${6^{th}}$ period of d-block does not come under transition elements.
(A) True
(B) False

Answer 1

An element whose atom has a partially filled d-orbital is called the transition element. These elements can give rise to cations when their d-orbitals are not completely filled. d-orbitals of a particular shell can include a maximum of 10 electrons.

Complete step by step solution:
We will see the definition of the transition elements and check whether Mercury is a transition element according to that definition or not.
- An element whose atom has a partially filled d-orbital is called the transition element. These elements can give rise to cations when their d-orbitals are not completely filled.
- We know that the transition metal compounds are called d-block elements. It includes group-3 to group-12 in the periodic table.
- However, not all the d-block elements are considered as transition metal elements. The elements situated in group-3 to group-11 have incomplete d-orbital while the elements of group-12 do not have an empty d-orbital. Actually, the d-orbitals in the group-12 elements have 10 electrons.
- The elements present in group -12 are Zinc (Zn), Cadmium (Cd) and Mercury (Hg). All these elements have a completely filled d-orbital. This is the reason why they are not considered as transition metal elements. However, they can exist in oxidation states like +1 and +2.

Thus, we can conclude that mercury does not come under d-block elements. So, the statement given in the question is true.

Note: Remember that as the elements like Zn, Cd and Hg are not included in transition metals elements, they are known as post-transition elements. However in metal complexes, the post-transition metals show similar behavior as the transition metals.