atomic orbitals and electron configurations 1.2 Flashcards
subshells
when emission spectra contain double or triple lines it suggests that the electron shells contain subshells which have different energies and shapes
how many electrons can each orbital hold
2
s orbitals
- spherical
- n = electron shell number
- as n decreases the diameter of the s orbital increases
p orbitals
- dumb bell shaped
- there are three orbitals so they hold 6 electrons
- each orbital is of equal energy (degenerate)
d orbitals
- they gave 5 d orbitals
- they can hold a total of 10 electrons
heisenbergs uncertainty principle
“it is impossible to determine the exact position and momentum of an electron”
the 4 quantum numbers
n , l , Ml , Ms
quantum number n
- principle quantum number
- tells you the electron shell number
- the higher n is the higher the potential energy
- n is a wave number starting from 1
quantum number l
- angular momentum quantum number
- describes the shape of an orbital within a subshell
- it has a value from 0 to (n-1)
quantum number Ml
- magnetic quantum number
- tells us what direction the orbitals have (x, y etc)
- have values -l to +l
quantum number Ms
- spin quantum number
- an electron behaves as if it has spin
- s can be +1/2 or -1/2
- shown with up or down arrows
- if there are 2 in an orbital they must have opposite spins
pauli exclusion principle
no two electrons in any one atom can have the same set of quantum numbers and each orbital holds a maximum of two electrons with opposing spins
hunds rule
“when degenerate orbitals are available electrons fill the orbitals singly keeping spins parallel before pairing occurs”
degenerate
same energy
aufbau principal
orbitals are filled in order of increasing energy and all orbitals within a subshell are degenerate
why do electrons fill the 4s orbital before the 3d orbital
because the 4s orbital has a low energy
the two exceptions in spectroscopic notation
copper and chromium
chromium spectroscopic notation
1s2 2s2 2p6 3s2 3p6 4s1 3d5
copper spectroscopic notation
1s2 2s2 2p6 3s2 3p6 4s1 3d10
why are copper and chromium exceptions
due to the increased stability that a full or half full shell gives
when do elements have a higher ionisation energy than expected
because the electrons are being removed from a complete orbital
are complete or incomplete orbitals more stable
complete and half full are more stable than incomplete
lone pairs
not all pairs or electrons are involved in bonding and these lone pairs affect the bond angle and shape
weakest to strongest repulsion
bonded to bonded pairs, lone to bonding, lone to lone