Chemical bonding and properties Flashcards
(31 cards)
Properties of ionic bonding
Mpt/Bpt - high
enthalpy of fusion - high (variable)
conduct - yes as aq not as sol
solub - gen very bc polar
ionic bonds
crystal, brittle, dense, hard
ex nacl
props of covalent network bonding
mpt/bpt - very high
enth of fusion - med - high
not conduct, semi conduct
insolub
covalent bonds
no molecs, dense, hard
ex SiO2
prop of metallic bonding
mpt/bpt - high(varies)
enth of fus - high (varies)
conduct as liq and sol
insoluble
metallic bonds
malleable, ductile, lustrous, can be dense
ex Ni
Props of molec polar and non polar bonding
bpt/mpt - low
the of fus - low
not conduct
slightly solub - depends on polar or not
intermolecular + covalent
low dense/hardness, not ductile, mall, lustrous
ex CO2
how to know which compound has higher melting point
metals have high
ionic crystals have high
if they have strong lattice structure(regular cubish shape)
allotropes of carbon and compare
diamond - interlocking struct, all elect are held
graphite - free elect in p orbital,conductor, sheets, weak LDF
graphene - single atome thick graphite, 2D, conduct, strong
fullerene - soccerball, stable, high mpt
nanotube - cylindrival
how does metallic bonding explain metal properties (mall, conduct, lustre)
Malleabl - elements cant hold elect well, weak bonds between atoms, sea allows atoms to slide
conduct - electron mobility - sea of electrons, delocalized electrons
lustre - mobile sea of elect absorbs and emit light
Describe what a semiconductor is and how its conductivity can be increased
with temperature or doping (Ex and how)
has silicon ,germanium - conduct small amt of electricity
Doping - adding impurities to make better
As - +1 val elect than Si, elect can jump up lvl and move to another atm better
B - -1 valelect thanSi, helps move elects
What does VSEPR theory stand for, how does it work
rules
Valence shell electron pair repulsion theory
3D geometry influenced by repulsion of electron pairs of atoms in molec
electron pairs will try to be as far away as possible
Lone pairs take up most space
5 (electron geometry) and their angles
linear - 180
trigonal planer - 120
tetrahedral - 109.5
trigonal bipyramidal - 90,120
octahedral - 90
molecular vs electron geometry
molec - vsepr, position of atomic nuclei
electron - ways in which valence electron are position, looks at lone pairs also
What are the 11 vspr shapes, what do they look like
linear,bent, trigonal planer, tetrahedral, trig pyr, trig bipyr, seesaw, tshape, octahedral, square planer, square pyr,
How does bonding happen using valence electron theory
+ limitations
form covalent bonds from valence orbitals
new orbital formed containing pair of elect
from overlapping
does not do dbl or trpl bonds
what is hybridization theory of orbitals and how does it work
+ex
combining orbitals to make new hybrid orbitals
ex CH4 - elect from 2s moves to empty 2p orbital so that each orbital type can bond with 1 H. Make sp orbital, has 4 spots called sp3 (3 elect from p orbitla)
how does hybridization relate to VSEPR
(#pair - electron geometry- hyb#) 6
pair - VSEPR shape - hyb
2 - linear - sp - 180
3 -trig planer - sp2 - 120
4 - tetrahedral - sp3 - 109.5
5- trig bipyramidal - sp3d
6 - octahedral - sp3d2
how does hybridization orbital relate to expanded octets
they use d orbitals in their hybridization
why expanded octet only works with group 3 onward
make each orbital only have 1 electron, move extras to d
what are sigma and pi bonds, how do they form
sigma - end to end overlap of orbitals, elect density btwn nucl, single bond
Pi - parallel bond, ex 2 py orbitl, usually dbl bond, from non hybridized orbitals, from partial hybridization
hoe do double and triple bonds form, ex
dbl- 1 sigma, 1 pi
trpl - 1 sigma bond, 2 pi bonds
define molec orbital theory
used to explain diatomicness and magneticness
math function, sin wave, describe where electrons most likely to be
relates to whole molecule
Antibonds and bonds made how
when making sigma bond
bonds - 2 1s orbitals overlap, constructive interference(in phase), make high vol low eng, likely to find elect in between atm, strong bonds
antibonds - +s and -s obtl overlap, destructive interference(out of phase), low vol high eng, low prob to find elect, weak bond
Properties of Molec orbitls
MOs num = num of atomic orbitals combined
2 made for each bond, 1 is antibond, other is bond
obey pauli, hund, aufbau rule
fill up 1 of both sigma p before adding second
How to predict bond order
Bond order = (# of bonded electrons - # of antibond elect)/2
1= single bond
2 = dbl
0 = no bond
1.5 = resonance
explain why some diatomic dont exist
if they have equal num antibond and bond elect
if bond order = 0
Ex He has 2 bonded and 2 antibonded
How to know if something is paramagnetic or diamagnetic
use molecular orbital diagram
if left over electrons without a pair then paramagnetic (O2)
if all are in pair than diamagnetic(N2)
