Atomic Structure

Question 1

What’s the relative mass and charge of a proton, neutron and electron?

Answer 1

Proton = 1, +1
Neutron = 1, 0
Electron = Negligible, -1

Question 2

Define relative atomic mass

Answer 2

Average mass of an element compared to 1/12 the mass of a carbon-12 atom

Question 3

What are isotopes of an element?

Answer 3

Same number of protons but different number of neutrons

Question 4

What are the 2 types of ionisation for a mass spectrometer?

Answer 4

1. Electron Impact
   electron gun knocks off one electron from each particle (forms +1 ions)
2. Electrospray
   sample dissolved in volatile solvent + injected through needle attached to high voltage power supply (particles gain a proton leaving the needle)

Question 5

When are each of these ionisation methods used?

Answer 5

Electron Impact = molecules with low formula mass
Electrospray = higher molecular mass

Question 6

How does mass spectrometer work?

Answer 6

Acceleration = +ve ions attracted towards -vely charged plate
Ion Drift = ions form a beam with constant kinetic energy along a tube to a detector
Detection = +ve ions pick up electrons (TOF is recorded)

Question 7

How many orbitals and shells do each s, p and d have?

Answer 7

s = 1, 2
p = 3, 6
d = 5, 10

Question 8

Why doesn’t Chromium or Copper fit the trend of electron configuration?

Answer 8

Cr = 1s2 ….. 3p6 4s1 3d5
Cu = 1s2 ….. 3p6 4s1 3d10

Question 9

Define 1st ionisation energy?

Answer 9

Energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions