chem h Unit 5

bonding and imf's

intramolecular forces

happens within a molecule

intermolecular forces

happens between separate molecules

electronegativity in bonding

EN determines the type of intra bond

Intra Ionic bonding

e- transferred from metal to non-metal. Forms ions. Big EN difference

intra metallic bonding

valence e- are shared with all atoms and “glue” metal atoms together. between two metals

intra covalent bonding

e- are shared and orbitals overlap. Similar EN, attract and repulse is equal. Non polar and polar.

Non- polar covalent bonds

equally shared e-. often diatomic

polar covalent bonding

unequal sharing of e-.

octet rule

When atoms bond, they tend to form the noble gas configuration of ns2 np6, which is 8 valence e-

different covalent bonds in decreasing strengths

triple, double, single

different covalent bonds in decreasing lengths

single, double, triple

breaking bonds

uses nrg, endothermic

forming bonds

releases nrg, exothermic

octahedral

6 e- pairs, 6 central atom bonds, 90º angles between each pair.

trigonal bipyramidal

5 e- pairs, 5 central atom bonds, 2 axial pairs (180), 3 equatorial pairs (120)

tetrahedral

4 e- pairs, 4 central atom bonds, 109.5º between each pair

trigonal planar

3 e- pairs, 3 central atom bonds, 120º between each pair

trigonal pyramidal

same thing as trigonal planar but with a lone pair on the central atom

linear

2 e- pairs, 1-2 central atom bonds, 180º between each pair

bent

linear but with 1-2 lone pairs on the central atom

neg side in a polar covalent bond

wherever the more EN atom is is more negative

HONC bonds

H-1, O-2, N-3, C-4

HONC lone pairs

H-0, 0-2, N-1, C-0 (onch)

dispersion forces

non-polar molecules, due to random fluctuation in e-,

dispersion forces strength

depends on how many e- there are or how long the molecule is

Dipole-dipole bonding

polar molecules, caused by attraction of permanent dipoles

hydrogen bonding

polar molecules, happens when H is bonded to N, O, or F

how do IMF’s affect molecule separation

High IMF = harder to separate

solubility

Like dissolves like

how do IMF’s affect surface tension

high IMF = high surface tension

how do IMF’s affect solubility

diff substances with similar IMF’s tend to mix

how do IMF’s affect boiling point

high IMF = high boiling point

how do IMF’s affect evaporation/volatility

high IMF = high volatility

how do IMF’s affect vapor pressure

high IMF = low vapor pressure

metal properties

high MP, solids at room temp, malleable and ductile, conducts in all states, Insoluble.

network covalent bonds

covalent bonds between molecules (diamond, graphite)

network covalent properties

high MP, hard, brittle, don’t conduct, insoluble

Ionic solids properties

High MP, solid at room temp, brittle, only molten and aqueous phases conduct, many soluble in water

noble gases properties

Low BP, gas at room temp, don’t conduct, insoluble in water, soluble in non-polar solvents

molecular solids properties

low BP, could be any phase at room temp, dont conduct, most are insoluble in water but are soluble in non-polar solvents