1.2

• Subatomic particle


  • Proton
  • Neutron
  • Electron
• Proton


  • Relative mass: 1
  • Relative charge: +1
  • Location in the atom: Nucleus
• Neutron


  • Relative mass: 1
  • Relative charge: 0
  • Location in the atom: Nucleus
• Electron


  • Relative mass: 1/1840
  • Relative charge: -
  • Location in the atom: Orbital shells
• Isotopes are chemically and physically the same
• Ion


  Particles where the number of electrons are not equal to the number of protons
• Positive ion (cation)


  Formed when an atom loses one or more electrons
• Negative ion (anion)


  Formed when an atom gains one or more electrons
• Radioactive decay


  Process that takes place when an atomic nucleus loses energy by emitting radiation
• Alpha decay


  • Type of radioactive decay where an atomic nucleus emits an alpha particle (2 protons and 2 neutrons)
  • Decreases the atomic number by 2 and the mass number by 4
  • Makes the element more stable
• Beta decay


  • Type of radioactive decay where a neutron is converted to a proton, an electron, and an antineutrino
  • Increases the atomic number by 1 and has no effect on the mass number
• Positron emission


  • Type of radioactive decay where a proton is converted to a neutron, a positron, and a neutrino
  • Decreases the atomic number by 1 and has no effect on the mass number
• Electron capture


  • Type of radioactive decay where an inner electron is captured by the nucleus, converting a proton to a neutron and emitting a neutrino
  • Decreases the atomic number by 1 and has no effect on the mass number
• Alpha, beta, gamma radiation


  Different types of radiation with varying penetrating power and ionizing ability
• Alpha radiation is the least penetrating, beta radiation is medium, and gamma radiation is the most penetrating
• Alpha and beta radiation can be deflected by electric fields, while gamma radiation is unaffected
• Half-life


  The time it takes for the radioactivity of a sample to decrease to half its original value
• Radiation can cause mutations in living organisms that can damage DNA and lead to cancerous tumours
• Ionization energy


  The minimum energy required to remove an electron from an atom
• Ionization energy increases down a group and across a period of the periodic table
• Factors that influence ionization energy include the number of protons, the subshell from which the electron is removed, and electron shielding
• Orbital regions within an atom are divided into subshells, which are further divided into orbitals
• Electrons fill orbitals according to the Aufbau principle, occupying available orbitals alone before pairing up
• The electron configuration of an element can be used to determine its chemical properties
• Emission and absorption spectra are produced by the absorption and emission of photons by electrons in an atom
• The frequency and energy of the photons emitted or absorbed are related by the equation E = hv
• The frequency of the convergence limit of the Lyman series can be used to calculate the first ionization energy of hydrogen
• Groups have different numbers of electrons in their outer shell (valence electrons).
• Lyman series


  When the excited electron falls back into the n-1 energy level (first shell), the energy of the emitted radiation is in the ultraviolet part of the electromagnetic spectrum
• Examination of the Lyman series

  Gives information about two key features of the hydrogen atom:
• Convergence limit


  • Within each series, the spectral lines become closer and closer together as the frequency of the radiation increases until they converge to a limit
  • Within the Lyman series, the frequency of this convergence limit corresponds to the energy required to remove the electron (ie. the ionisation energy)
• Ionisation energy


  The transition between the n-1 level and the convergence limit, where the energy levels are so far from the nucleus that they are effectively the same energy. At this point, the electron is effectively removed from the atom.
• The transition from n=1 to n = corresponds to the atom losing the electron completely. The ionisation energy of the hydrogen atom corresponds exactly to the highest frequency line in the Lyman series of the hydrogen atom spectrum since they both refer to exactly the same process.
• Measuring the convergent frequency allows the ionisation energy to be calculated from E=hf.
• What is plancks constant (h)?


  6.626 x 10^-34 Js