Intro to MO and Diatomic Molecules

Wavelength

Horizontal distance between the crests or between the troughs of two adjacent waves

Frequency

the number of complete wavelengths that pass a point in a given time

wavelength and frequency

inversely proportional

wavelength and energy relationship

The shorter the wavelength, the higher the energy

constructive interference

The interference that occurs when two waves combine to make a wave with a larger amplitude

destructive interference

The interference that occurs when two waves combine to make a wave with a smaller amplitude

sigma bond

formed when two atomic orbitals combine to form a bonding orbital

in-phase

constructive interference

stabilizing (lower energy)

Sigma antibonding orbital

formed when two atomic orbitals combine to form a anti-bonding orbital around the axis

out-of-phase

destructive interference

high energy

MO Diagram for H2

pi bond

a bond that is formed when parallel orbitals overlap above and below axis

in-phase

pi* antibonding molecular orbital

a bond that is formed when parallel orbitals overlap above and below axis

out-of-phase

MO diagram

Energy level diagram for showing the relative energies and electron occupancy of the MOs for a molecule

rules for MO diagram

1. Number of electrons in MO = number of electrons in two starting atoms
2. Number of orbitals in MO = number of orbitals in two starting atoms
3. Total energy of orbitals in MO = energy of starting atoms

diatomic molecule

A molecule consisting of two atoms

Diatomic MO pattern

bond order

the number of shared electron pairs between two atoms

bond order equation

(# bonding electrons - # antibonding electrons)/2

diamagnetic

all electrons are paired

paramagnetic

Atom or substance containing unpaired electrons and is consequently attracted by a magnet.

Which is shorter (sigma or pi bond)?

pi bond