PHYSICAL PROPERTIES of CRYSTALLINE SOLIDS (Answers)
Crystal Type Metallic
Property
Hardness and
malleability
Melting and
boiling points
Electrical and
thermal
conductivity
Variable hardness,
malleable rather than
brittle
Very variable,
dependent on # of
valence electrons
Good in all states
Solubility
Insoluble except in
other metals to form
alloys
Examples
Fe(s), Cu(s), Pb(s),
Ti(s), Cr(s), Co(s)
Ionic
Covalent Network
Molecular
Hard, but brittle
Very hard, but brittle
High m.p.  usually
over
500 ºC
Do not conduct as
solids, but do conduct
when molten or in
solution
More soluble in water
than other solvents
Very high m.p. 
usually over
1000 ºC
Do not conduct in any
state (graphite &
graphene are
exceptions).
Insoluble in all
solvents
Usually soft and
malleable unless
hydrogen bonded
Low m.p  usually
under
200 ºC
Do not conduct in any
state
- C(s)(diamond, graphite,
NaCl(s), CaCO3(s),
MgBr2(s), Mg(OH)2(s) graphene)
-SiO2 (quartz)
-SiC (moissonite)
More soluble in nonaqueous solvents,
unless they can
hydrogen bond to
water
- CO2(s), C2H5OH(s),
I2(s), H2O(s)
SUMMARY #2 (Answers)
IONIC
COMPOUNDS
Volatility
Solubility in polar
solvent, e.g. water
Low
Soluble
Solubility in nonpolar solvent, e.g.
hexane
Electrical
Conductivity
Non-soluble
Conduct when
molten(l) or
dissolved in
water(aq)
POLAR
COVALENT
COMPOUNDS
Higher
Solubility increases
as polarity
increases
Solubility increases
as polarity
decreases
Non-conductors
NON-POLAR
COVALENT
COMPOUNDS
Highest
Non-soluble
GIANT
COVALENT
Soluble
Non-soluble
Non-conductors
Non-conductors
except graphite,
graphene and semiconductivity of
silicon and
(molecular)
fullerene, C60
Low
Non-soluble
Definitions:
(i) VOLATILE  A substance is volatile if it evaporates at a low temperature (under 100°C). [*e.g. Acetone (CH3COCH3) and gasoline are volatile liquids.]
(ii) SEMICONDUCTOR  A solid substance that has a conductivity between that of an insulator and that of most metals, either due to the addition of an
impurity or because of temperature effects.