Question

12. Discuss Hard soft acid base theory 13. Discuss high and low spin complexes and how they relate to liable compounds and non- liable compounds.

Answer 1

Solution:-

Acid and bases are the characterised by acceptance and donation of loan pair of electrons respectively..Ease of donation and acceptance pair of electron depends on the size of atoms hence it may characterized Hard and Soft acid/ bases.

It explains that soft acids or bases tend to be large and very polarizable, while hard acids or bases are small and non-polarizable.

Generally, we could characterize hard acids and bases as having:

1. Small atomic radii

2. Low polarizability

3. High positive charge (3+ or higher)

4. High electronegativity (base)

5. High charge density

6. High oxidation state

Simillarly we could characterize soft acid and bases as having

1. Large atomic radii

2. High polarizability

3. High Negative charge

4. Low electronegativity

5. Low charge density

Atoms or ions having property between them characterized under borderline some example as following which is mention in below table

Table of hard, borderline, and soft acids and bases

	Hard	Borderline	Soft
Acids	K+, Al3+,Sr2+,Cr3+	Ni2+,Rh3+,Ir3+	Cu+,Pd2+,Tl+
Bases	OH-,NH3,SO42-,F-	Br-,NO2-,N2	SCN-,RS-,I-