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Structure 1.2 Flashcards

Active Recall for The Nuclear Atom

1.2.1 Subatomic Particles: read all 6 questions and answers
  1. What are the three subatomic particles?
    Proton (charge +1, mass 1 amu), Neutron (charge 0, mass 1 amu), Electron (charge -1, mass ~1/1836 amu).
  2. What is the Atomic Number (Z)?
    The number of protons in the nucleus. It defines the element and determines its position in the periodic table.
  3. What is the Mass Number (A)?
    The total number of protons and neutrons in the nucleus. A = Z + number of neutrons.
  4. Where is virtually all the mass of an atom located?
    In the nucleus, which contains protons and neutrons. The electrons contribute negligible mass.
  5. How is the number of neutrons calculated?
    Number of neutrons = Mass Number (A) - Atomic Number (Z).
  6. What determines the chemical properties of an element?
    The electron configuration, which is determined by the number of protons (atomic number).
1.2.2 Isotopes & Mass Spectrometry: read all 6 questions and answers
  1. Define isotopes.
    Atoms of the same element (same number of protons/atomic number) with different numbers of neutrons (different mass number).
  2. Why do isotopes have identical chemical properties?
    Because they have the same electron configuration. Chemical properties depend on electrons, not neutrons.
  3. Why do isotopes have different physical properties?
    Because they have different masses (different numbers of neutrons), affecting properties like density, rate of diffusion, and melting/boiling points.
  4. List the 4 stages of mass spectrometry.
    1. Vaporisation, 2. Ionisation (electron bombardment), 3. Acceleration (electric field), 4. Deflection (magnetic field), then Detection.
  5. How is relative atomic mass (Ar) calculated from mass spec data?
    Ar = sum of (isotope mass x percentage abundance) / 100.
  6. What does the height of each peak in a mass spectrum represent?
    The relative abundance of that isotope.
1.2.3 Emission Spectra: read all 6 questions and answers
  1. What causes an atomic emission spectrum?
    Electrons absorb energy and are excited to higher energy levels. When they fall back down, they emit photons of specific frequencies, producing a line spectrum.
  2. Why do emission spectra have discrete lines?
    Because electron energy levels are quantised. Only specific energy transitions are possible, producing photons of specific frequencies.
  3. What does convergence of spectral lines indicate?
    It indicates that energy levels get closer together at higher energies. The convergence limit corresponds to ionisation energy.
  4. How can the first ionisation energy be determined from an emission spectrum?
    From the convergence limit of the highest-energy series (Lyman series for hydrogen). The frequency at convergence corresponds to the ionisation energy.
  5. What is the difference between a continuous and a line spectrum?
    A continuous spectrum contains all wavelengths (e.g. White light). A line spectrum contains only specific wavelengths, produced by excited atoms.
  6. Why is the hydrogen emission spectrum important?
    It provides evidence for quantised energy levels and was key to developing the Bohr model of the atom.
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