Atomic Structure

    Cards (54)

    • What is the charge of the nucleus in an atom?
      Positively charged
    • What particles are found in the nucleus?
      Neutrons and protons
    • What is the relative charge of an electron?

      -1
    • What is the typical radius of an atom?
      1×1010 metres1 \times 10^{-10} \text{ metres}
    • How does the radius of the nucleus compare to the radius of an atom?
      The nucleus is 10,000 times smaller
    • Where is most of the mass of an atom concentrated?
      At the nucleus
    • What is the arrangement of electrons in an atom?
      • Electrons lie at different distances from the nucleus
      • They occupy different energy levels
      • Arrangements may change with EM radiation
    • What do all atoms of the same element have in common?
      The same number of protons
    • What defines a neutral atom?
      It has the same number of electrons and protons
    • What are isotopes?
      Atoms with the same protons but different neutrons
    • Give an example of isotopes of carbon.
      Carbon-12, Carbon-13, Carbon-14
    • How does the charge of a normal neutral atom balance out?
      Electrons equal protons
    • What happens if there are more electrons than protons?
      The atom has a negative charge
    • What occurs when electrons change orbit?
      They absorb or emit EM radiation
    • What happens when electrons move to a higher orbit?
      The atom absorbs EM radiation
    • What happens when electrons fall to a lower orbit?
      The atom emits EM radiation
    • What can happen if an electron gains enough energy?
      It can leave the atom, forming a positive ion
    • What did Rutherford discover about the nucleus?
      It could be broken down into smaller particles
    • Who provided evidence for the existence of neutrons?
      James Chadwick
    • What is radioactive decay?
      A random process of nucleus changing to stability
    • What is activity in terms of radioactive decay?
      The rate of unstable nuclei decaying
    • How is activity measured?
      In Becquerel, Bq
    • What is count-rate in radioactive decay?
      The number of decays recorded per second
    • What is alpha decay?
      A helium nucleus emission
    • How ionising is alpha radiation?
      Highly ionising
    • How penetrating is alpha radiation?
      Weakly penetrating (~5cm of air)
    • What is beta minus decay?
      An electron emission
    • How ionising is beta radiation?
      Medium ionising
    • What is gamma radiation?
      High-energy electromagnetic radiation
    • How ionising is gamma radiation?
      Low ionising
    • How penetrating is gamma radiation?
      Highly penetrating (very far in air)
    • What are nuclear equations used for?
      To represent radioactive decay
    • What happens to the mass and charge during alpha decay?
      Both decrease
    • What happens to the mass during beta decay?
      It does not change
    • What happens to the charge during beta decay?
      It increases
    • What happens to mass and charge during gamma decay?
      Neither changes
    • Can the decay of a single nucleus be predicted?
      No, it cannot be predicted
    • How can the half-life be used in radioactive decay?
      To predict activity of many nuclei
    • If 80 atoms decay to 20 in 10 minutes, what is the half-life?
      5 minutes
    • What characterizes a short half-life?
      Less long-term radioactive risk