How does bond formation affect the energetics of the bond?

Question

I am an 11th grade student who has just started learning about bonds in compounds. My question pertains to a line written in JD Lee's Concise Inorganic Chemistry for JEE (Main and Advanced)

It was suggested that in all such case, a pair of electrons gets unpaired and one of the electrons is excited to the next available vacant orbital of slightly higher energy. The driving force for this process is the energy released in bond formation by unpaired electrons.

If we have an atom with its initial energy as 'x'J. and further add 'k'J of energy to it so as to excite the electron, then (according to this line), the energy released after bond formation is 'k'J, leading to a final energy of 'x'J.

We have been taught that the purpose of a bond is to lower the total energy. But here, the final and initial energies are same. Then what is the purpose of a bond? Perhaps I'm simply interpreting the line wrong, or is the bonding mechanism more complex than a simple "energy less"?

Answer 1

final and initial energies are the same

Now you have a perfect equilibrium between A + B <--> A-B

But this depends greatly on what A and B are.

Electrons do not have to be "excited" for bonding to occur. It usually happens to complete the electron "shells", forming a more stable molecule. More stable means lower energy. Therefor, in that case the bonding reaction is favored.

"Covalent" bonds are so much more favored that for all practical purposes, the reaction of A + B is 100% A-B. Weaker ionic bonds, such as salts, exhibit varying degrees of dissociation. Here the "lower energy state" depends greatly on the "solvent effects".