Summary Bonding Notes - AQA Chemistry A Level

Bonding
Types of Bonding
 Ionic
o Metal/ammonium and non-metals
o Strong electrostatic forces of attraction between oppositely charged ions
o Giant ionic structure
o Strength of bonds depends on charge and size of ion
 Covalent
o Between non-metals
o Shared pair of electrons
o Simple molecular and giant covalent structures
o Strength of bonds depends on size/Mr of molecule and strength of intermolecular
forces
 Metallic
o Between metal ions and delocalised electrons
o Strong electrostatic forces between positive metal ions and sea of delocalised
electrons
o Giant metallic structure
o Strength of bonds depends on size/charge of ion and number of delocalised
electrons

Ionic Bonding
 Metal atom loses electrons and becomes a positively charged cation
 Non-metal atom gains electrons and becomes a negatively charged anion
 Opposite charges attract and ions held together by strong electrostatic forces of attraction
 Strength of ionic bonding depends on:
o Charge on ion – greater charge, stronger ionic bonding
o Size of ion – smaller ion, stronger ionic bonding

Covalent Bonding
 Shared pair of electrons – atoms are held together by strong electrostatic forces of
attraction between the shared eletron pair and positive nuclei of both atoms

Coordinate (Dative Covalent) Bonding
 A shared pair of electrons where both electrons have originated from one atom
 Drawn using a -> rather than a line, showing the direction the electrons are donated
 Identical to normal covalent bonds – same length, strength





 Lewis Acid – Electron pair acceptor

,  Lewis Base – Electron pair donor

Metallic Bonding
 Electrostatic forces of attraction between positive ions and the sea of delocalised electrons
 Strength of metallic bonding depends on:
o Strength of electrostatic forces of attraction between positive metal ions and sea of
delocalised electrons
o Smaller, more highly charged ions with lots of delocalised electrons – stronger
metallic bonds

Crystal Types
Monoatomic
 All gases at room temperature
 Single atoms held by very weak forces of attraction
 E.g. Noble gases

Ionic





 High melting and boiling points
o Strong electrostatic forces of attraction between oppositely charged ions require
lots of energy to break
 Conducts electricity when molten or aqueous
o Ions are free to move when liquid or in solution as electrostatic forces have been
broken
 Brittle
o Force pushes ions into a position where charges are aligned and repel each other
 Soluble in water
o Polar water molecules pull ions away from the lattice, causing it to dissolve

Metallic
 High melting and boiling points
o Strong electrostatic forces of attraction between metal ions and sea of delocalised
electrons
 Conducts electricity
o Delocalised electrons are free to move
 Malleable
o Layers of cations can slide over each other whilst maintaining the eletrostatic
attraction
 Insoluble