Atomic Structure

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

  It has evolved with scientific understanding.
• What did the Plum Pudding Model propose about atoms?

  Atoms consist of a sphere of positive charge.
• What is the current understanding of 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 charge does the nucleus of an atom have?

  Overall positive charge.
• In a neutral atom, how do the number of electrons compare to protons?

  They are equal in number.
• What is the relative charge of a proton?

  +1
• What is the relative charge of a neutron?

  0
• What is the relative charge of an electron?

  -1
• What is the relative mass of a proton?

  1
• What is the relative mass of a neutron?

  1
• What is the relative mass of an electron?

  1/1840
• How can the maximum number of orbiting electrons in a shell be 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 represent?

  The sum of protons and neutrons.
• What does atomic number 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 do isotopes have in common?

  Same atomic number but different neutrons.
• How do neutral atoms of isotopes react chemically?

  They react the same way due to electron configuration.
• What physical properties differ among isotopes?

  Different mass numbers lead to different properties.
• What is an ion?

  An atom that has lost or gained 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 ionisation process of mass spectrometry?

  1. Sample vapourised and injected.
  2. High voltage ionises atoms, forming +1 ions.
• What happens during the acceleration phase in mass spectrometry?

  • Positively charged ions are accelerated.
  • They move towards a negatively charged detection plate.
• What occurs during the ion drift phase in mass spectrometry?

  • Ions are deflected by a magnetic field.
  • Their path radius depends on charge and mass.
• What happens during the detection phase in mass spectrometry?

  • Positive ions hit the detection plate.
  • They gain an electron, producing a flow of charge.
• How is analysis performed in mass spectrometry?

  • Current values and flight times are combined.
  • A spectra print-out shows relative abundance of isotopes.
• What effect does a 2+ charged ion have on its path in mass spectrometry?

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

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

  
• What does the chlorine spectra produced by mass spectrometry show?

  A characteristic pattern in a 3:1 ratio for Cl⁺.

  
• What is the significance of the 3:6:9 ratio in Cl₂⁺ ions?

  It indicates different combinations of isotopes.

  
• What are the types of electron orbitals?

  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, lowest to highest energy.