If we take Wurtz reaction there are two free radicals formed, why is it necessary for the free radical electron to be of opposite spins there? Is it like for bonding or gaining stability they change the spin?
Answers
Answer:
This is a brilliant question.
Well, as you've guessed it's for bonding, the two radicals unless and until don't have opposite spins,cannot pair up to form a bond in the Bonding molecular orbital, because remember finally, the sigma bond formed between those two carbon atoms will be decided as in the hybrid orbital, and hence to fill the bonding molecular orbital, the electrons necessarily have to be of opposite spin, electrons having same spin cannot pair up together to form a bond.
However,apart from reactions, when the atom's electronic configuration is written down, then for filling multiple electrons in the same subshell, we first put one one electron in each orbital (That is Hund's Rule of multiplicity from Atomic chemistry) and this is done because same spin electrons in half filled orbitals can exchange each other like teleporting from one orbital to another and gain extra energy called the pairing energy.
However in reactions to form a bond, opposite spin is required always, otherwise same spin electrons in same orbital can cause instability.
Hope this helps you !