Article: Note that each shell lies further and further out from the nucleus of the atom. According to the property of entropy, energy always seeks the lowest possible state of order. The electrons will seek to populate the lowest orbital shells available. When two atoms come together to form a molecule, they seek to use each other's electrons to fill the lowest possible states in the electron orbital shells. Bonding electrons are, essentially the electrons that stick together and fall into the lowest states. Antibonding electrons are the "free" or unbonded electrons that are pushed to higher orbital states.  Bonding electrons: By noting how full the orbital shells of each atom are, you can determine how many of the electrons in higher energy states will be able to fill the more stable, lower-energy-state shells of the corresponding atom. These "filling electrons" are referred to as bonding electrons. Antibonding electrons: When the two atoms try to form a molecule by sharing electrons, some electrons will actually be driven to higher-energy-state orbital shells as the lower-energy-state orbital shells are filled up. These electrons are referred to as antibonding electrons.
What is a summary of what this article is about?
Consult a diagram of electron orbital shells. Know the difference between bonding and antibonding orbitals.