1. Bonding in Solids There are four classifications of solids, depending
on the type of bonds that are present.
Ionic Solids
Covalent-Network Solids
Metallic Solids
Molecular Solids

2. Ionic Solids - Form of particles: Positive and negative ions
Forces between particles: Electrostatic attractions
Properties: Hard and Brittle
High melting point
Poor thermal and electrical conductivity when solid
Electrical conductivity if molten or dissolved
Examples: All typical salts. e.g. NaCl, Ca(NO3)3, MgBr2 + -

3. Covalent-Network Solids
Form of particles: Atoms connected in network of covalent bonds
Forces between particles: Covalent bonds
Properties: Very Hard
Very high melting point
Usually poor thermal and electrical conductivity
Examples: Diamond (C), Quartz (SiO2), Silicon ( Si)
Diamond
Each carbon is connected to
4 others by a covalent bond

4. Metallic Solids
Form of particles: Atoms
Forces between particles: Metallic Bonds (due to
delocalized valence electrons)
Properties: Soft to very hard
Low to very high melting point
Excellent thermal and electrical conductivity
Malleable and Ductile
Examples: All metals. e.g. Cu, Fe, Sn, Au, Ag
Bonding due to delocalized valence
electrons (shown in blue)

5. Molecular Solids
Form of particles: Atoms or molecules
Forces between particles: Dispersion
Dipole-Dipole (if molecules are polar)
Hydrogen Bonds (if O-H, N-H, F-H)
Properties: Fairly soft
Moderately low melting point (usually <200 oC)
Poor thermal and electrical conductivity
Examples: Argon , CH4, CO2,
C6H12O6 (sucrose), H2O