Molecular orbital band theory Flashcards
how are bonding and anitbonding MO’s formed?
by combining the atomic orbitals of eg. two Li atoms
What happens when MO’s are so close together in energy?
they form a continuum or BAND of MO’s- almost as if the entire piece of metal were one enormous molecule
What do you call the lower energy MO’s and what are they occupied by?
occupied by valence electrons
called valence band
What do you call the higher energy MO’s and what do they contain?
- these are empty orbitals
- make up the conduction band
true or false; there is no energy gap between the conduction band and the valence band
true
what are the electrons capable of, when they receive an infinitesimally small amount of energy?
electrons can jump from filled valence band to the empty conduction band?
why do electrons jump from the valence band to the conduction band even when only a small amount of energy is supplied?
- the electrons will be free to move throughout the piece of metal and the metal conducts electricity easily
What causes metallic lustre (shine)?
consequence of the continuous band of MO energy levels
true or false; all frequencies of light can be absorbed and emitted as electrons move between the valence and conduction bands
true
what happens when metal wire is heated?
the electrons are said to be excited, and their extra energy are transferred along the wire length
What else does band theory help explain other than the bonding of metals?
metalloids and non metals
true or false; metalloids and non metals can also combine to form bands of MO’s
true
how large is the energy gap between the valence band and the conduction band in metalloids?
small energy gap
how large is the energy gap between the valence band and the conduction band between non metals
large energy gap
true or false; metals are conductors
true
