The structure and properties of solids
The physical properties of solids are related to their intermolecular forces. (Examples of physical
properties: hardness, melting point, conductivity, malleability, ductility)
Because forces vary in strength, we can classify them into different categories:
1) Ionic (metal/non-metal) 
2) metallic (metals only) 
3) molecular (non-metals only) 
4) covalent network (metalloids and carbon) 
The details…
Type of Crystal structure
crystal
Ionic
Lattice (repeating pattern of atoms):
Metallic
Continuous and compact
Valence electrons are loosely held and
mobile “electron sea”:
Bonds or
intermolecular
forces
Ionic Bonds = Very
strong
Metallic = decently
strong BUT nondirectional
Physical properties
Hard, brittle,
conductor (in liquid
state), high mp/bp
(strong bonds)
Shiny/silvery
(valence e’s absorb
+ emit light),
flexible/good
conductor
(electrons move
freely)
Molecular Lattice like ionic, but packed according
to shape and size:
Intermolecular:
Dipole-dipole
London
Hydroge
= weak!!
Low mp/bp, not very
hard (weak
intermolecular
forces), can’t
conduct electricity
(individual
molecules are
neutral)
Covalent
network
Covalent bonds:
fairly strong… but
the strength is
amplified by the
interlocking
covalent network =
STRONG! (more so
than ionic!)
Very hard/very
brittle/high melting
points (Because
MANY bonds are
formed to make
network),
insoluble/don’t
conduct electricity
(electrons are
trapped in the
network)
Large tetrahedral network with each
carbon (or silicon) atom covalently
bonded to four other carbon atoms (aka
covalent network). Ie: diamonds,
quartz: