4th lecture - many electron atoms Flashcards
why cant the schrodinger equation be used on atoms with more than 1 e-
the equation includes V (potential energy - which involves the repulsion between e-, however for H this is 0 as there is only 1 H)
we would need to first find the electron probability distribution but we need to schrodinger answer to find this ;\
how can the H atom orbital wave functios be used for many electrons
orbitals are the same shape for each element
when atoms have more than one e- what do the orbital energies depend on
n + l
not just n like for H atom
describe e- with higher ‘n’ quantum numbers
probability distribution further from the nucleus
experience less effective nuclear charge due to shielding
higher energy
less stable
what is shielding + what does it do
shielding is when electrons with a lower ‘n’ value prevent outer electrons from feeling the full nuclear charge that they would if it wasnt for the closer ones.
it gives the outer electrons more energy than they should - less stable, less tightly bound
what charge actually acts on outermost electrons
effective nuclear charge
nuclear charge - shielding
why is the 2s orbital lower in energy than the 2p orbital
plotting radial distribution function against radius:
2s: m but with one hump being much smaller
2p: one big n shape
2s has a residual max closer to the nucleus meaning e- can penetrate closer to the nucleus + experience greater effective nuclear charge, lowering their energy
what effect does Z (nuclear charge) have on electron orbitals
decrease orbital energy
higher electrostatic attraction : more penetration : lower energy as they get closer to the nucleus.
what happens to the 4s orbital as u move across the period
gets lower in energy
higher Z experienced (nuclear charge)
more penetration towards the nucleus
what does penetration refer to
ability for an electron to occupy a space closer to the nucleus
increases with increasing nuclear charge
aufbau principle
electrons occupy the lowest energy orbitals first
pauli exclusion principle
no 2 electrons in any given system can have the same 4 quantum numbers
aka: the 2 electrons must have 2 different spins //Ms values (+1/2 or -1/2)
are all orbitals always present? even when theres no e- occupying them?
yes girl ofccc!!
hunds rule
e- will only pair up in orbitals if they have to due to not wanting to experience repulsion
most stable: all e- having the same spins in different orbitals. aka 3 p e- in different boxes all facing one way (up)
what is a core electron
electrons that help fill up orbitals until theyre completely full
