what happens to electrons in a covalent bond

In a covalent bond, electrons are not traded or stuck between atoms; they are shared in a common orbital that belongs to both atoms at once.

Quick Scoop

• Each atom contributes (usually) one electron to form a shared pair.
• That pair occupies a molecular orbital that spreads over both nuclei.
• The shared electrons spend more time between the nuclei, pulling them together and lowering the energy of the system.

• This sharing lets each atom “feel” like it has a full outer shell (octet or duet), which makes the molecule more stable.

• In polar covalent bonds, the pair is shared unequally and spends more time near the more electronegative atom.

Think of it less like “my electron vs your electron” and more like both atoms placing electrons into a joint safety deposit box they both access continuously.

What actually happens to the electrons?

1. They form a shared orbital

Quantum mechanically, the electrons in a covalent bond occupy a bonding molecular orbital that extends over both atoms.

• The electron density is concentrated between the two nuclei.
• Both nuclei attract the same electrons, which pulls the atoms together and stabilizes the bond.

So an electron in a covalent bond is not hopping back and forth between “Atom A” and “Atom B”; it exists in a single delocalized state spread over both.

2. They give each atom a “full” outer shell

Atoms covalently bond because sharing electrons helps them reach a stable electron configuration:

• Hydrogen shares to get 2 electrons in its outer level.
• Most main‑group atoms share to effectively have 8 valence electrons (the octet rule).

The key point: each shared pair counts toward the valence shell of both atoms at the same time.

When the covalent bond breaks

When you break a covalent bond, the shared electrons must be redistributed, and there are two main ways this can happen:

1. Homolytic cleavage (even split)
   • Each atom takes one electron from the shared pair.
   • You get two neutral radicals (each with an unpaired electron).

 * This is common when the two atoms are the same or very similar (like in O₂).

2. Heterolytic cleavage (uneven split)
   • One atom takes both electrons from the shared pair.
   • You get a negatively charged ion (gains both electrons) and a positively charged ion (gets none).

 * This is more likely when one atom is significantly more electronegative or when the environment stabilizes ions (like in water).

So: the electrons don’t disappear; they either split 1–1 or go together with whichever atom holds them more tightly.

Polar vs nonpolar sharing

• Nonpolar covalent bond : electrons are shared almost equally (e.g., H₂, Cl₂). The electron cloud is symmetric.

• Polar covalent bond : one atom pulls the shared electrons closer (e.g., O–H in water), giving it a partial negative charge and the other a partial positive charge.

This unequal sharing is a big reason molecules like water have strong polarity and special properties.

Mini recap (TL;DR)

• In a covalent bond, electrons occupy a shared molecular orbital that covers both atoms.

• This shared electron pair gives each atom a more stable, “full” outer shell.

• When the bond breaks, the electrons are either split evenly (homolytic) or both go with one atom (heterolytic), depending on electronegativity and environment.

Information gathered from public forums or data available on the internet and portrayed here.