Atomic and Molecular Structures Flashcards
What are resonance structures?
- the ideal formal charge on a neutral atom is = 0
- a lot of charge in one spot is unstable (lots of energy)
- therefore, spread out energy by spreading out the charge and lowering the energy (e- move freely) (partial charges)
What is the most ideal structure of an atom?
a stable atom with a formal charge of 0
= valence e- - number of pi and sigma bonds attached - nonbonding e-
= valence e- - (sticks + dots)
VSEPR shapes: linear
X - A - X
180 degrees
lone pairs: 0
VSEPR: trigonal planar
A, X, X, X
120 degrees
lone pairs: 0
VSEPR: tetrahedral
A, X, X, X, X,
109.5 deg
lone pairs: 0
VSEPR: trigonal pyramid
A X, X, X,
107deg
lone pairs: 1
VSEPR: bent
A X, X
104.5 deg
lone pairs: 2
VSEPR: trigonal bipyramidal
A, X, X, X, X, X
180, 90, 120
lone pairs: 0
VSEPR: octahedral
A X, X, X, X, X, X
180, 90
lone pairs: 0
What is the strongest dipole-dipole intermolecular force?
Hydrogen bonding
Define intermolecular force
electrostatic interactions between charges or partial charges on DIFFERENT molecules
Heisenberg uncertainty principle
the momentum and position of the electron are impossible to determine with accuracy
Pauli Exclusion principle
no two electrons can possess the same 4 quantum numbers
Principal quantum number
n
- shell
larger n = higher energy and larger radius
Azumithal quantum number
l (angular momentum)
- subshells/sublevels
- s p d f = 0 1 2 3
Magnetic quantum number
ml
- orbital
- (-l to +l)
- orbitals i.e. px, py, pz
Spin quantum number
ms
- +/-1/2
- same number = parallel (different orbitals)
- different number, same orbital (paired)
Hund’s rule
e- in subshells will fill other orbitals first before filling same orbital twice
Aufbau principle
e- will fill in lowest energy (n+l) first before higher energies
Paramagnetic
- unpaired electrons present
- magnetic field aligns with spins of the electrons
Diamagnetic
- no unpaired electrons
- repels magnetic field
