Question
Chemistry Question on d -and f -Block Elements
In following pairs, the one in which both transition metal ions are colourless is :
A
Sc3+, Zn2+
B
Ti4+, Cu2+
C
V2+, Ti3+
D
Zn2+, Mn2+
Answer
Sc3+, Zn2+
Explanation
Solution
Scandium ions (Sc+3) and zinc ions (Zn+2) are colorless due to the absence of unpaired electrons. In contrast, transition metal ions such as copper ions (Cu+2), titanium ions (Ti+3), vanadium ions (V+2), and manganese ions (Mn+2) exhibit color as they possess unpaired electrons.
When these transition metal ions absorb light in the visible region, an unpaired electron from a lower energy d orbital is excited to a higher energy d orbital. The observed color is complementary to the absorbed light frequency.
So, the correct option is (A): Sc3+, Zn2+