Atomic Structure (P1+P3) Flashcards
Define ionisation energy
The amount of energy needed to remove 1 mole of electrons from 1 mole of atoms in the gaseous state.
1st IE for potassium
2nd IE for potassium
3rd IE for potassium
1st = K - K+ + e-
2nd = K+ - K2+ + e-
3rd = K2+ - K3+ +e-
Factors affecting IE
nuclear charge
distance from nucleus
shielding
Electronic Configuration of Ca2+ ion
expected = 1s2 2s2 2p6 3s2 3p6 4s2
correct = 1s2 2s2 2p6 3s2 3p6
Why are chromium and copper exceptions of electronic configurations?
d block elements are more stable when they have a full or half full subshell
Why are D block ions exceptions of electronic configurations?
electrons are removed from the 4s subshell
4s = first in first out
Electronic configuration of Fe2+ ion
Expected= 1s2 2s2 2p6 3s2 3p6 4s2 3d6
correct= 1s2 2s2 2p6 3s2 3p6 3d6
Down a group
IE decreases
atomic radius increases
shielding increases
Across a group
Atomic radius decreases
shielding stays same
How does a mass spectrometer work?
- acceleration - positive ions attracted to negative plate and accelerate towards it
- Ion drift - ions will pass through a hole in negative plate heavier particles cant keep up with lighter ones
- detection - each ion hits detector it gains an electron
current is proportional to relative abundance.
2 reasons why it is necessary to ionise isotopes before they can be analysed in mass spectrometer
- allows ions to be accelerated towards negative plate
- allows ions to be detected
Electron Impact ionisation
- High energy electrons
- fired at sample with electron gun
- which knocks off 1 electron
X(g) - X+(g) +e-
Electrospray Ionisation
- Sample dissolved in volatile solvent
- injected through hyperdermic needle connected to high voltage power supply
- particles gain a proton
X(g) + H+ - XH+(g)
How to calculate Ar
(mass x abundance)+(mass x abundance)+(mass x abundance) / total abundances
Define Ar
mean mass of an atom / 1/12 mass of an atom of C12
