Chapter 7 Flashcards
VSPER
says electrons want to get as far away from each other in a 3D space
Axn
A is central atom, x is # of electron pairs, n positive whole numbers
highly symmetric molecule
every angle is the same
electron domain geometry
describes only the positions of bonding pairs.
molecular geometry
describes positions of all electron pairs.
5 electron domain geometries
linear, 2 terminal atoms trigonal planar, three terminal atoms tetrahedral: 4 terminal atoms trigonal bipyramidal: 5 terminal atoms octahedral: 6 terminal atoms
which electron-domain geometry does not exhibit high symmetry
trigonal bipyramidal
angle in linear electron domain
180
angle in trigonal planar geometry
120
angle in tetrahedral geometry
109.5
angles in trigonal bipyramidal geometry
90 (b/w top and middle) and 120 (b/w 2 middle atoms)
angle in octahedral geometry
octahedral
2 bonded pairs molecular geometry
linear
2 BP 1 LP mol. geometry
bent
2 BP 1 LP mol. geo.
bent
2 BP 3 LP molecular geo.
linear
3 BP molecular geometry
trigonal planar
3 BP 1 LP mol. geometry
trigonal pyramidal
3 BP 2 LP mol. geometry
t-shaped
4 BP mol. geometry
tetrahedral
4 BP 1 LP mol. geometry
seesaw
4 BP 2 LP mol. geometry
square planar
5 BP mol. geometry
trigonal bipyramidal
5 BP 1 LP mol. geometry
square pyramidal
6 BP mol. geometry
octahedral
why are multiple bonds counted as single pairs?
there is only 1 sigma bond in a 2 or 3 pair.
sigma bond
formed by head-on-head overlap. represent single bonds. Only one in double and triple bonds.
pi bonds
formed by side-to-side overlap. 1 in double bonds and 2 in triple bonds
polarity criteria
- must have polar bonds
2. the overall dipole is the vector sum of individual dipoles (so if they cancel, they are not polar)
molecules that are usually polar
non-symmetric molecules and when there is the presence of at least one lone pair.
types of intermolecular forces
dispersion, dipole-dipole, hydrogen bonding, ion-dipole interaction
ion-dipole interaction
happens when there is an ion and a polar substance
dispersion forces
happen in everything
hydrogen bonding
occur when H is paired with a highly electronegative element (N, O, F) that has at least one lone pair.
dipole-dipole
occurs when a polar molecule interacts with another polar molecule
what causes nitrogen (a non-polar gas) to become liquid when temp. drops
dispersion forces, heavier things are harder to turn into a gas
low boiling point corresponds with what kind of dipole moments?
low dipole moments, and weak attractions
valence bond theory
atoms share electrons when an atomic orbital on one atom overlaps with an atomic orbital on another. It balances electron attraction with repulsion from protons.
according to valence bond theory, how many bonds would you expect an oxygen atom to form
2
problems with valence bond theory
simple diatomic molecules are the only things that can be explained by VB theory. (# of orbitals and degrees do not match p)
hybridization
using atomic orbitals in a combination to form hybrid orbitals that have correct geometry to explain bonding in larger molecules.
tetrahedral (4 bonds) electron domain hybridization
sp3
trigonal planar (3 bonds) electron domain hybridization
sp2
linear (2 bonds) electron domain hybridization
sp
trigonal bipyramidal (5 bonds) electron domain hybridization
sp3d
octahedral (6 bonds) electron domain hybridization
sp3d2
is it possible to hybridize just part of the atomic orbitals
yes
