Intermolecular Forces and
Physical Properties
Chemistry
Unit 6
Non-Polar Covalent Compounds
Examples: O2, CH4, CO2
Types of particles: 2 or more non-metals
IMF’s = Dispersion
Physical state – can be s, l, or g –
depends on molecular weight (MW)
Melting/Boiling Pts. – very low to low
Solubility in water – Not soluble
Conductivity – poor to non conducting.
Polar Covalent Compounds
Examples: H2S, HCl, H2O
Types of particles: usually 2 or more nonmetals
IMF’s = Dipole-Dipole and maybe hydrogen
bonds
Physical state – can be s, l, or g – depends on
molecular weight (MW)
Melting/Boiling Pts. – low to medium
Solubility in water – most are soluble
Conductivity – Do not conduct.
Ionic Compounds
Examples: NaCl, MgO
Types of particles: Metal and Non-metal
IMF’s = Ionic bonds
Physical state – crystalline solids, brittle
Melting/Boiling Pts. – very high
Solubility in water – most are soluble
Conductivity – conduct as liquids or when
dissolved in water..
Metallic
Examples: Al, Cu, Fe
Types of particles: cations in sea of electrons
IMF’s = metallic bonds
Physical state – all solids except Hg
Melting/Boiling Pts. – variable – depends on
charge and size
Solubility in water – Not soluble
Conductivity – conduct as solids or liquids
Covalent Network Compounds
Some covalently bonded substances DO
NOT form discrete molecules.
Diamond, a network of
covalently bonded carbon
atoms
Graphite, a network of
covalently bonded carbon
atoms
Network Covalent Solids
Network solids – solids in which
all the atoms are covalently
bonded to each other
Network solids melt at very high
temperatures, or not at all (decomposes)
– Diamond does not really melt, but
vaporizes to a gas at 3500 oC and
beyond
– SiC, used in grinding, has a melting
point of about 2700 oC
Network Covalent
Examples: Carbon, Silicon, SiO2, C60
Types of particles: usually single atoms
IMF’s = covalent bonds
Physical state – solids
Melting/Boiling Pts. – very high
Solubility in water – Not soluble
Conductivity – poor to non conducting.
Diamond vs. Graphite
Different properties due to how it is bonded.
Diamond – very hard, high mp- carbons 4 bonds
each
Graphite – soft solid –carbons have 3 bonds
BuckyBalls – C60
Allotropes of Carbon
Allotropes of carbon Link
Types of Molecular Solids
Covalent
Molecular
Covalent
Network
(H2O)
(SiO2 - quartz)
Amorphous
(SiO2 - glass)