Covalent bond

A covalent bond is sharing of electrons between atoms to achieve stable electronic configuration.

Single, Double, Triple, Coordinate covalent bond.

Usually low melting and boiling points (except network solids), poor electrical conductivity, often soluble in non-polar solvents.

Non-polar: negligible ΔEN (H₂, Cl₂). Polar: moderate ΔEN with partial charges (HCl, H₂O, NH₃).

Dot-and-cross structures for shared pairs (e.g., H₂O: two bonding pairs + two lone pairs on O).

Elements with vacant d-orbitals (P, S, Cl) can expand the octet → multiple valencies (PCl₃ vs PCl₅, SF₆).

FC = Valence e⁻ − (Nonbonding e⁻ + ½×Bonding e⁻); used to judge the most stable resonance form.

Bond length (triple < double < single); Bond angle (CH₄ 109.5°, NH₃ 107°, H₂O 104.5°); Bond enthalpy (triple > double > single); Bond order (integer or fractional with resonance).

Incomplete octet (BeCl₂, BF₃); Expanded octet (SF₆, PCl₅); Odd-electron species (NO, NO₂).

A covalent bond is sharing of electrons between atoms to achieve stable electronic configuration.

Single, Double, Triple, Coordinate covalent bond.

Usually low melting and boiling points (except network solids), poor electrical conductivity, often soluble in non-polar solvents.

Use dots or crosses to represent shared electron pairs (e.g., H₂O has two bonding pairs and two lone pairs around O).

Elements with vacant d-orbitals (e.g., P, S, Cl) can expand their octet and show multiple valencies (PCl₃ vs PCl₅, SF₆).

FC = (Valence electrons) – (Nonbonding electrons + ½ Bonding electrons). Helps identify the most stable resonance structure.

Incomplete octet (BeCl₂, BF₃), expanded octet (SF₆, PCl₅), odd electron species (NO, NO₂), molecules with less than or more than 8 electrons.