Hi, love your website. I've been studying chemistry for a long time and have this one question pondering in my head:

Why does atom need to achieve octet or duplet in order to be stable? If so, why compounds/atoms become more stable after every bond (ionic/covalent) is made?

Or put simply, why does bond making is exothermic? Is it because when bonds are made, the electrons are drawn closer to the nucleus, so kinetic energy of the electrons are lost as heat energy? Therefore, this loss in energy causes
The new compound to be more stable than its original atom. So, an atom will tend to make as many covalent bonds as possible. For ex: PCl5 is more stable than PCl3 because it contains more covalent bonds?