SUMMARY

• How has the model for atomic structure changed over time?

  It has evolved with scientific understanding
• What was the Plum Pudding Model of atomic structure?

  Atoms were thought to be a positive sphere with negative charges
• What does the Electron Shell Model state about atomic structure?

  Atoms have a dense nucleus with orbiting electrons
• What experiment led to the discovery of the Electron Shell Model?

  The Rutherford scattering experiment in 1911
• What particles make up the nucleus of an atom?

  Protons and neutrons
• What is the overall charge of the nucleus?

  Positive charge
• Why do neutral atoms have equal numbers of protons and electrons?

  To balance the overall charge
• What are the relative charges and masses of protons, neutrons, and electrons?

  • Proton: Charge +1, Mass 1
  • Neutron: Charge 0, Mass 1
  • Electron: Charge -1, Mass 1/1840
• How is the maximum number of electrons in a shell calculated?

  Using the formula $2n^2$
• How many electrons can shell 2 hold?

  8 electrons
• What must happen before the next electron shell can hold electrons?

  Each electron shell must fill first
• What does mass number (A) represent?

  The sum of protons and neutrons
• What does atomic number (Z) represent?

  The number of protons in an atom
• If an atom has an atomic number of 7 and a mass number of 14, how many neutrons does it have?

  7 neutrons
• What is relative atomic mass (Ar)?

  Mean mass of an atom divided by carbon-12 mass

  
• What are isotopes?

  Atoms with the same atomic number but different neutrons
• How do neutral atoms of isotopes behave chemically?

  They react chemically in the same way
• What affects the physical properties of isotopes?

  The different mass numbers of isotopes
• What are examples of isotopes of hydrogen?

  • Hydrogen: 1 proton, 0 neutrons
  • Deuterium: 1 proton, 1 neutron
  • Tritium: 1 proton, 2 neutrons
• What are ions?

  Atoms that lose or gain electrons
• What is mass spectrometry used for?

  To identify different isotopes and relative atomic mass
• What does Time of Flight (TOF) Mass Spectrometry measure?

  The time ions take to reach a detector
• What are the steps in the mass spectrometry process?

  1. Ionisation: Sample vapourised and ionised
  2. Acceleration: Ions accelerated towards detection plate
  3. Ion Drift: Ions deflected by magnetic field
  4. Detection: Ions hit detection plate, producing current
  5. Analysis: Current values used to produce spectra
• What happens during the ionisation process in mass spectrometry?

  Electrons are removed, creating +1 charged ions
• How are ions accelerated in mass spectrometry?

  They are accelerated towards a negatively charged plate
• What does the radius of an ion's path depend on in mass spectrometry?

  Charge and mass of the ion
• What occurs when positive ions hit the detection plate?

  They gain an electron, producing a flow of charge
• How is the relative abundance of isotopes displayed in mass spectrometry?

  Through current values and flight times in spectra

  
• What happens to a 2+ charged ion in a magnetic field?

  It produces a smaller radius path
• How is relative atomic mass (Ar) calculated using isotopes?

  Using the formula $Ar =$ \frac{(10 \times 75) + (12 \times 25)}{75 + 25}

  
• What is the characteristic pattern of chlorine spectra in mass spectrometry?

  A 3:1 ratio for Cl⁺ ions

  
• Why do chlorine spectra show a 3:6:9 ratio for Cl₂⁺ ions?

  Different combinations of isotopes form chlorine molecules

  
• What types of orbitals do electrons occupy?

  s, p, d, and f orbitals

  
• How many electrons can an s-orbital hold?

  2 electrons
• How many electrons can a p-orbital hold?

  6 electrons
• How many electrons can a d-orbital hold?

  10 electrons
• In what order are orbitals filled?

  From s to d, increasing energy
• What is the electron configuration of sodium (Na)?

  Na = 1s²2s²2p⁶3s¹
• What is the significance of electron pairing in orbitals?

  It stabilizes the atom by reducing repulsion
• What are the three rules for writing electron configurations?

  1. Fill the lowest energy orbital first
  2. Same spin electrons fill an orbital before pairing
  3. No orbital holds more than 2 electrons