orbital theory Flashcards
ionisation energy definition
The amount of energy required for an atom to lose one or more electrons.
First ionisation
Energy required to lose one mole of electrons from one mole of gaseous atoms to form gaseous ions
second ionisation
The energy required for an atom to lose on mole of electrons from one mole of gaseous 1+ ions to form gaseous 2+ ions
e.g (ca+(g) = ca2+ + e)
successive ionisation
If there is a large jump in ionisation energies then the nergy principle has changed (no longer the valence shell) this can be used to suggest the group
ionisation energy across groups
decreases as you go down as there are more shells and the outermost electron is further from the nucleus (less pull)
ionisation energy across periods
increases across periods as there is a greater nuclear charge
orbital shapes
s orbital- spherical
p orbital- dumbbell shaped made up of three lobes
how much can each shell hold?
s orbital- 2
p orbital- 6 (3 lobes)
d orbital- 10 (5 lobes)
what are orbitals?
regions of space around a nucleus where you are more likely to find an electron of a particular energy
rules for filling up energy levels
placed in the lowest energy orbital available
can hold only two electrons if they have opposite spin
order
1s 2s 2p 3s 3p 4s 3d 4p
(exception of chronium and copper as 3d begins to fill with only one electron in 4s)
orbitals on ionisation energy
p orbital has lower as it is further from the nucleus with more shielding
bonding pairs make for a lower ionisation energy due to the repulsion between the bonding pair
overall summary
-bonding pair in outer shells= more repulsion + lower first ionisation energy (FIE)
-p orbital on outer shell= lower FIE as it is further from nucleus than s orbital
-further from nucleus= more shielding and lower FIE (decreases down a group)
- more protons in nucleus= higher FIE as more nucleus pull
