Topic 1: Atomic Structure Flashcards
Atomic Number
(Z) No. protons in an atom
Relative Atomic Mass meaning
(A) No. protons + neutrons in an atom
Isotopes
Same protons, different neutrons
Energy level (shells) vs energy
Higher the energy level the higher the energy the further from the nucleus they are
Orbitals
Each holds 2 electrons and is a region of space around the nucleus where an electron is most likely to be found.
Order of filling electrons
1s,2s,2p,3s,3p,4s,3d,4p (just draw the diagram)
Cromium (Cr) Electron Configuration
(1s2 2s2 2p6 3s2 3s6) 4s1 3p5 Exception to have more stability with its half filled 3d orbital
Copper Electron Configuration
(1s2 2s2 2p6 3s2 3p6) 4s1 3d10 Exception to have more stability with its full filled 3d orbital
Ionisation Energy
Energy required to remove a mole of electrons from a mole of gaseous atoms to form one mole of gaseous ions.
Ionisation Energy Trend
Across period - increases - increased nuclear charge, smaller atomic radii
Down group - decreases - increased shielding
Jumps in ionisation energy in an element
Due to change in energy level, can determine what element it is from.
Mass Spec Stages
1) Ionisation
2) Acceleration
3) Ion Drift
4) Detection
(5) Data Analysis)
Electron Bombardment
Using an electron gun fire high energy electrons at the sample, this knocks an electron off the atoms creating 1+ ions.
Acceleration
All have the same kinetic energy, lighter ions will travel faster because of KE= 1/mv^2.
Ion Drift
Allows for separation between lighter and heavier ions.
Detection
As ions hit the ion detector, a current is induced (think of it accepting the electrons which in itself is a current). The greater the current, the higher the abundance.
m/z
mass/charge (if charge is 1 then this is just the mass)
Relative Atomic Mass Calculation
((mass1xabundance1) + (mass2xabundance2))/total abundance
Electrospray Ionisation
- Sample dissolved in volatile solvent
- Forced through fine needle connected to positive side of high voltage supply
- Produces tiny droplets which have gained a proton from the solvent
- Solvent evapourates in in vaccum so droplets get smaller
- Only single positively charged ions are left
Kinetic Energy Equation
KE = 1/2 MV^2
Relative atomic mass definition
The average mass of an atom of an element relative to one twelfth of the mass of an atom of carbon-12
