Atomic Structure

• What are the three sub-atomic particles?

  Proton, neutron, electron
• Where are protons located in an atom?

  In the nucleus
• What is the relative mass of a neutron?

  1
• What is the relative charge of an electron?

  -1
• How is an atom of Lithium represented?

  $^{7}_{3}Li$
• What does the atomic number, Z, represent?

  Number of protons in the nucleus
• What is the mass number, A?

  Total number of protons and neutrons
• How do you calculate the number of neutrons in an atom?

  Number of neutrons = A - Z
• What are isotopes?

  Atoms with the same protons, different neutrons
• Why do isotopes have similar chemical properties?

  Same electronic structure
• How can isotopes vary in physical properties?

  Different masses
• What is the purpose of a mass spectrometer?

  Identify elements and isotopes in a sample
• What are the four essential steps in a mass spectrometer?

  1. Ionisation
  2. Acceleration
  3. Flight Tube
  4. Detection
• What is the first step in a mass spectrometer?

  Ionisation
• What technique is used in electron impact ionisation?

  Firing high energy electrons at a sample
• What happens during electro spray ionisation?

  Sample gains a proton from the solvent
• What is required for the mass spectrometer to function properly?

  It needs to be under a vacuum
• What occurs in the acceleration area of a mass spectrometer?

  Positive ions are accelerated by an electric field
• How does the mass of ions affect their flight time in the flight tube?

  Heavier particles take longer to move
• What does the detection area of a mass spectrometer do?

  Generates a current for analysis
• What is the relationship between current and abundance in mass spectrometry?

  Current is proportional to abundance
• How do you calculate the time of flight for an ion?

  t = d / v
• What is the mass/charge ratio (m/z) used for?

  To measure isotopes in mass spectrometry
• What is the relative atomic mass (R.A.M) based on?

  Weighted average of all isotopes
• How do you calculate R.A.M from isotopic mass and abundance?

  R.A.M = Σ(isotopic mass x % abundance) / 100
• What is the R.A.M of magnesium given the isotopes and their abundances?

  24.3
• How do you express the species for a peak in a mass spectrum?

  Give charge and mass number
• What happens to a molecule in a mass spectrometer with electron impact ionisation?

  It often breaks up into fragments
• What is the molecular ion peak in mass spectrometry?

  Peak equal to the relative molecular mass
• What occurs when a molecule is ionised by electro spray ionisation?

  No fragmentation occurs
• How do you find the relative molecular mass from an electro spray ionisation peak?

  Subtract 1 from the MH+ peak
• What is the shape of s sublevels?

  Spherical
• How are electrons arranged in the atom according to the A-level model?

  In principle energy levels and sub-levels
• What is the order of filling sub-shells in an atom?

  1s → 2s → 2p → 3s → 3p → 4s → 3d
• What does the box represent in a spin diagram?

  One orbital
• How many electrons can the p sublevel hold?

  Up to 6 electrons
• What happens when filling orbitals with multiple orbitals?

  Fill each orbital singly before pairing
• What happens to electrons when a positive ion is formed?

  Electrons are lost from the outermost shell
• What happens to electrons when a negative ion is formed?

  Electrons are gained in the outermost shell
• What is the electronic structure of magnesium?

  1s2 2s2 2p6 3s2