(6) crystal field stabilisation energies

Question 1

what is the energy change when a octahedron splits its d-orbitals into lower and higher energy levels

Answer 1

lowers = -2/5 
raises = +3/5

Question 2

which electron orbitals are destabilising

Answer 2

eg orbitals ( +3/5 )
increases energy of system by ( +3/5 )

Question 3

which electron orbitals are stabilising

Answer 3

t2g orbitals ( -2/5 ) 
lowers energy of system by ( -2/5 )

Question 4

what effect do electron pairs have on the systems energy

Answer 4

the pair ( P ) increases the energy
destabilising the system

Question 5

describe the John teller distortion

Answer 5

when the degenerate orbitals are unsymmetrically filled, which means the system changes bond lengths to become more stable

Question 6

describe what happens when an electron enters the eg anti bonding orbital

Answer 6

if an electron was to enter the eg - dz2 orbital, there would be more anti bonding character along the z axis so the system would undergo tetragonal distortion and would elongate the z-axis to reduce the anti bonding character …

an electron in the dz2 orbital would repell a dx2-xy2 empty orbital so the bond would be longer