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*Revision Materials and Past Papers* 1 Atomic Structure 2 Amounts of Substance 3 Bonding 4 Energetics 5 Kinetics 6 Chemical Equilibria & Kc 7 Redox Equations 8 Thermodynamics 9 Rate Equations 10 Kp (Equilibrium Constant) 11 Electrode Potentials & Cells 12 Acids and Bases 13 Periodicity 14 Group 2: Alkaline Earth Metals 15 Group 7: The Halogens 16 Period 3 Elements & Oxides 17 Transition Metals 18 Reactions of Ions in Aqueous Solution 19 Intro to Organic Chemistry 20 Alkanes 21 Halogenoalkanes 22 Alkenes 23 Alcohols 24 Organic Analysis 25 Optical Isomerism 26 Aldehydes & Ketones 27 Carboxylic Acids & Derivatives 28 Aromatic Chemistry 29 Amines 30 Polymers 31 Amino Acids, Proteins & DNA 32 Organic Synthesis 33 NMR Spectroscopy 34 Chromatography RP1–RP12 Required Practicals

1.3 Bonding

1.3.1 Ionic Bonding 1.3.2 Covalent Bonding 1.3.3 Metallic Bonding 1.3.4 Bonding and Physical Properties 1.3.5 Shapes of Molecules 1.3.6 Bond Polarity 1.3.7 Forces Between Molecules

Nature of Covalent and Dative Covalent Bonding

Specification Reference Physical Chemistry, Bonding 3.1.3.2

Quick Notes

  • A covalent bond is a shared pair of electrons between two atoms.
    • The positively charged nuclei of both atoms are attracted to the shared pair of negatively charged electrons, pulling the atoms closer together.
  • Single bond = one pair of electrons shared
  • Double bond = two pairs of electrons shared.
  • Triple bond = three pairs of electrons shared.
  • A dative covalent (coordinate) bond forms when one atom provides both electrons in the bond.
  • Covalent bonds are shown with a line (–).
  • Dative covalent bonds are shown with an arrow (→) pointing from the donor atom.

Full Notes

Covalent and dative covalent bonding has been outlined with more background theory here and here.

This page is just what you need to know for AQA A-level Chemistry :)

Covalent Bonds

Covalent bonding often occurs between non-metal atoms. Each atom shares electrons to achieve a full outer shell or stable electron configuration.

The shared electron pair forms a strong electrostatic attraction between the nuclei and the bonding electrons.

The distance between nuclei is called the bond length. Shorter bond lengths mean stronger bonds.

Example: Hydrogen (H2): H–H

AQA A-Level Chemistry covalent bonding diagram showing two hydrogen atoms sharing electrons to form H2

Multiple Covalent Bonds

Sometimes, atoms share more than one pair of electrons:

These bonds are shorter and stronger than single bonds.

Example:Two oxygen atoms share two pairs of electrons, forming O2 with a double bond.

AQA A-Level Chemistry double covalent bonding diagram showing O2 molecule with two shared electron pairs

Dative Covalent (Coordinate) Bonds

A dative covalent bond is a covalent bond where both electrons come from one atom. Once formed, it is identical to a normal covalent bond in strength and length.

Represented with an arrow (→) from the donor atom to the acceptor atom.

AQA A-Level Chemistry diagram of a coordinate bond showing electron pair donated from one atom to another

Example:Ammonium ion (NH4+) is formed when NH3 donates a lone pair from N to H+.

AQA A-Level Chemistry ammonium ion formation showing NH3 donating lone pair to H+ forming NH4+

Representing Bonds

Covalent bonds are represented with lines in bonding diagrams.

Bond Type Symbol Description
Single covalent bond – One shared pair of electrons
Double bond = Two shared pairs
Triple bond ≡ Three shared pairs
Dative covalent bond → Both electrons come from one atom

Photo of Matt
Matt’s exam tip

Only ever draw lines for bonding in covalent substances – never use a line with ionic bonding.
For example Na-Cl is wrong as there is no covalent bond between the Na and Cl. H-H is fine however, because the two hydrogen atoms are held together by a covalent bonding.

Summary

Term Definition
Covalent bond Shared pair of electrons between two atoms
Multiple bonds Two or three shared pairs of electrons
Dative covalent bond Shared pair where both electrons come from one atom
Representation Use a line for covalent bonds and an arrow for dative bonds