Question

Which of the following statement is wrong for the transition elements?

• A. Transition elements are placed from and period
• B. Last electron enters in orbital
• C. Exhibits variable valency
• D. General electronic configuration is

Answer 1

The correct option is A

Transition elements are placed from and period

We remember that the d- orbitals start from $3^{rd}$ shell i.e. $3d$ is the first d-orbital while filling the electronic configuration of elements. And we also know that the d-block elements are called as transition elements.

But we know in transition elements, last electron enters in $(n-1)d$ orbital, therefore $n$ = $4$, because first d-orbital is $3d$. Hence d-block elements are placed from $4^{th}$ period to $7^{th}$ period in the periodic table.

Some general properties of Transition elements are:

(i) Last electron enters in $(n-1)d$ orbital

(ii) General electronic configuration is $(n-1)d^{1-10}n{s}^{0-2}E$

(iii) Exhibits variable valency

So the option (A) which states that 'Transition elements are placed from $3^{rd}$ and $6^{th}$ period' is false.