Salam Academy
Sign inCreate account
Learn7405Paper 1 · Paper 1: Physical and inorganic chemistryBondingTypes of bonding
Bonding · Subtopic 1 of 3

Ionic, Covalent, Dative and Metallic Bonding

Ionic bonding is electrostatic attraction between oppositely charged ions in a giant lattice; smaller, more highly charged ions attract more strongly. Metallic bonding is attraction between cations and delocalised electrons. A covalent bond is a shared pair attracted to both nuclei; in a dative (coordinate) bond both electrons come from one atom (NH4+\mathrm{NH_4^+}, Al2Cl6\mathrm{Al_2Cl_6}). Head-on orbital overlap gives a σ bond; sideways p-orbital overlap gives a π bond. Period 3 atoms can expand the octet (PCl5\mathrm{PCl_5}, SF6\mathrm{SF_6}).

Cambridge 9701 Paper 1Cambridge 9701 Paper 2Edexcel YCH11 WCH11AQA 7405 Paper 1≈ 45 minRevision 1 · updated 2026-10-30
Section 1 of 14

Learning objectives

  • Describe ionic, metallic, covalent and dative bonding.
  • Explain σ and π bonds and hybridisation.
  • Relate bond strength and length.
  • Explain physical properties from structure and bonding.
Pause and think

Why does magnesium oxide melt at 2852 °C but sodium chloride at only 801 °C?

Section 2 of 14

Core idea

Start hereFour ways to hold atoms together

Diamond, salt, copper and ammonium chloride are held together in completely different ways. The type of bond decides whether a substance melts, conducts or dissolves.

The big idea

Ionic: electrostatic attraction between ions. Metallic: cations and delocalised electrons. Covalent: shared pairs, including dative bonds. Orbital overlap gives σ and π bonds.

1. σ and π bonds

Orbital overlap

Head-on vs sideways.

Worked exampleBonds in a molecule

Count σ and π bonds in propenenitrile, CH2=CH−C≡N\mathrm{CH_2{=}CH{-}C{\equiv}N}.

Goal
Totals.
Strategy
Each bond has 1 σ; extra bonds are π.
  1. C–H:3σ\text{C–H}: 3\sigma
    Three H atoms.
  2. C=C:1σ+1π; C–C:1σ\text{C=C}: 1\sigma+1\pi;\ \text{C–C}: 1\sigma
    Double and single.
  3. C≡N:1σ+2π\text{C}\equiv\text{N}: 1\sigma+2\pi
    Triple bond.
Answer6 σ and 3 π.
✓ Checkσ bonds: 3+1+1+1=63+1+1+1=6 ✓.
Key takeawayDative bonds Shown by an arrow from donor to acceptor. Once formed, a dative bond is identical to other covalent bonds.
Pause and think

Why is silicon dioxide a solid but carbon dioxide a gas?

Summary

  • Ionic, metallic, covalent, dative.
  • σ + π.
  • Structure explains properties.
Key words
Dative bond
Covalent bond where both electrons come from one atom.
Sigma bond
Bond formed by head-on orbital overlap.
Pi bond
Bond formed by sideways overlap of p orbitals.
HistoryLinus Pauling. Linus Pauling introduced hybridisation and electronegativity in the 1930s; his book The Nature of the Chemical Bond won him the 1954 Nobel Prize.
Fun factAluminium chloride's double life. Aluminium chloride vapour is made of Al₂Cl₆ dimers held together by dative bonds, but at higher temperatures it splits into AlCl₃ molecules.
Keep reading for free

Create a free account to read the rest of this lesson: key formulae, worked examples, explore the graph, common mistakes, exam tip, guided practice and more. Your answers are checked and your progress is saved.

Create free accountSign in