Atomic Structure

Atomic Structure
Metall...
made up of metal atoms stacked in
a lattice and a sea of free valence
electrons
electrostatic attraction between atoms and
valence electrons is non dimensional and
strong
ionicbo...
Metal + nonmetal transfer electrons to from anions () and cations (+)
covalent bonding
Form between two or more nonmetal atoms
Electrons are shared between atoms
Lewis structures
Total all valence electrons in the molecule
Place remaining pairs around the outer atoms so that they each have 8 electrons
Bond polarity
Caused by differences
in electronegativity
If difference in electronegativity
is less than 0.5, then the
covalent is nonpolar
Polar covalent molecules
occur when the bond
polarities do not cancel.
What make...
electron arrangement
nucleus
Protons (P+)
Neutrons (n)
Properties of i...
solubility
variable solubility in
water (see solubility
rules)
electrical conductivity
as molten and solution only
as need free moving ions
hardness
brittle
when forced, layers of
ions shift causing positive
and negative ions to align
and repel.
Properties of covalent compounds
giant covalent networks
diamond structure
solubility
insoluble in water and non
polar substances
electrical conductivity
nil, no free electrons
melting point
very high strong covalent bonds
hardness
very hard strong covalent bonds
silicon dioxide structure
bucky balls structure
graphite structure
solubility
insoluble in water and
nonpolar solvents
electrical conductivity
conducts electricity due to
free electrons between
layers
melting point
very high strong covalent bonds
hardness
layers slide over eachother weak
Van Der Waals forces between
layers
simple covalent molecules
solubility
soluble in water if polar, soluble in
nonpolar solvents if nonpolar
electrical conductivity
nil no free electrons or
charged particles
melting point
Very low MP is dependant
on size of atoms in the
molecule
hardness
nil, mostly gas, liquids of
soft solids at room
temperature
Breaking Van Der
Waals forces
dipoledipole
interactions
in molecules containing
polar covalent bonds
Hydrogen
bonding
between molecules
containing O, H or F
atoms
these are stronger than the
other types of Van Der Waal
forces
This leads to higher than
expected melting points
instantaneous dipole
moments
halogens
melting point increases
down the group
in molecules containing
nonpolar covalent bonds
These dipole
moments get stronger
the more electrons
there are in the
molecule
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