The +5 oxidation tate of bi is less stable then its +3 state explain
Answers
Why is bismuth in its +5 oxidation state least stable than its +3 oxidation state?
This is known as , where the two s-orbital electrons of bismuth is less prone to take part in a chemical bond than the three p-orbital electrons.
The explanation of this effect considered s electrons being more tightly bound to nucleus than p electrons, owing to electrons shielding or to relativistic stabilization of s orbital. This reasoning was flawed, it is inconsistent with ionization energy data.
Drago offered another explanation, whose reasoning begins with higher oxidation compounds having bonds with covalent nature, rather than ionic. To get enough energy to attain higher oxidation state, such covalent bonds should be strong. If covalent bonds are weak, only lower oxidation state is attained.