Question

Explain the formation of a chemical bond.

Answer 1

A chemical bond is an attractive force that holds atoms or ions together in a chemical species.

Atoms combine to form bonds mainly to attain a more stable, lower-energy state, often by achieving a noble gas–like configuration of valence electrons (octet or duplet).

Octet Concept (LaTeX)

Many main-group atoms tend to adjust their valence electrons so that they have 8 electrons in their outermost shell: \[ \text{Stable configuration} \;\Rightarrow\; 8 \text{ valence electrons (octet)} \]

How Bonds Are Formed

• Ionic bond: Formed by complete transfer of electron(s) from a metal atom to a non-metal atom. The metal forms a cation and the non-metal forms an anion, both reaching stable configurations. Example: Na -> Na^{+} + e^{-} Cl + e^{-} -> Cl^{-} Na^{+} + Cl^{-} -> NaCl} 
• Covalent bond: Formed by sharing of electron pairs between two atoms so that each attains an octet (or duplet for hydrogen). Example H2 molecule: H + H -> H:H

Energy Aspect

When a bond forms, the potential energy of the system decreases because the attractive forces between nuclei and electrons dominate over repulsive forces.

This decrease in energy is released as heat or light, and the bonded state is more stable than the separated atoms.