Covalent bond

Beware from falling in this trapdoor:
Magnetic interaction between spins is not what holds the bond together.
It gives a tiny contribution but it is very minute.

What mainly reduces the binding partners combined total energy when a bond is formed and
what thus gives the vast majority of the binding force is the following:
Upon bonding the matter wave of the electron can spread out around the nucleus of the binding partner too and
according to the Heisenberg uncertainty principle more spread in volume means less spread in impulse and thus less kinetic energy.
This is because the phase space volume of an electron in ground state (volume spread impulse spread) always stays minimal.

Related

• Coordinate bond – weaker bond where both electrons come from one atom – related: Electron deficiency bond
• The issue of Inter system crossing in Mechanosynthesis.
  Spins must align before a bond can form.
• The basics of atoms – The nature and shape of atoms
• Atomic orbitals

External Links

Wikipedia:

• Covalent bond
• Exchange interaction
• German wikipedia: [1] – Exchange interaction as the attractive component in covalent bonds.