IE

• Ionisation Energy


  The energy required to remove an electron from an atom
• Factors influencing Ionisation Energy

  • Atomic Radii - Larger atomic radii means higher energy levels are further away from the nucleus
  • Nuclear Charge (# protons) - More charge pulls electrons in closer. (+ and - attract each other)
  • Shielding effect - Blocking effect?
• Calculating Ionization Energy


  1. h = Planck's constant

  2. c = speed of light

  3. L = Avogadro number

  4. E = h * L = wavelength of radiation
• There are as many ionisation energies as there are electrons in the atom
• Successive ionisation energies for potassium

  • Potassium is in group 1
  • Notice the "jump" in energy needed to remove the 2nd electron
• The different "jumps" are evidence for the arrangement of electrons in energy levels and sub-levels
• Successive ionisation energies for an element in group 4

  Notice the "jump" in energy needed to remove the 5th electron
• Successive ionisation energies for an element in group 2

  Notice the "jump" in energy needed to remove the 3rd electron
• Successive ionisation energies for an element in group 3

  Notice the "jump" in energy needed to remove the 4th electron
• Successive ionisation energies for an element in group 5

  Notice the "jump" in energy needed to remove the 6th electron
• Successive ionisation energies for an element in group 1

  Notice the "jump" in energy needed to remove the 2nd electron
• Valence electrons are the electrons in the outermost energy level of an atom
• Successive ionisation energies for potassium

  1st ionisation energy
• Interpretation of Ionization Energy graphs

  • He > H - nuclear charge is greater - one extra proton
  • Li < He - increased nuclear charge, but outer electron is held less strongly
  • Be > Li - increased nuclear charge
  • Mg > Na - electrons in the same energy level
  • B < Be - despite the increased nuclear charge, the outer electron is held less strongly
  • Al < Mg - it is now shielded by the 3s energy sub-level and is also further away
  • O < N and S < P - despite the increased nuclear charge the electron is easier to remove in O, in N the three electrons in the 2p level are in separate orbitals whereas in O two(2) of the 4 electrons are in the same orbital, repulsion between paired electrons means less energy needed to remove one
  • Na < Li - despite the increased nuclear charge the electron is easier to remove from Na, increased shielding and greater distance from the nucleus, outer electron in Na is held less strongly and easier to remove
• Periodically there was a large drop in the energy to remove electrons, caused by the electrons being further from the nucleus
• The energy required to remove electrons was sometimes less than expected due to shielding from filled sub-levels, example O < N
• Filled orbital causes more repulsion thus greater shielding
• Atomic Radii


  The size of an atom, measured as the distance between the nucleus and the outermost energy level containing electrons. A larger atomic radii results in a lower ionization energy.
• Electron Shells


  Regions around the nucleus where electrons are most likely to be found. Each shell corresponds to a specific energy level and can hold a fixed number of electrons. The outermost shell, also known as the valence shell, plays a crucial role in determining the chemical properties of an element.
• Mass of radiation


  The rest mass energy of a particle, given by E=mc^2, where m is the mass of the particle and c is the speed of light.
• Planck-Einstein relation


  E = h \* c / wavelength, where E is the energy of a photon, h is Planck's constant, c is the speed of light, and wavelength is the distance between two consecutive crests or troughs in a wave.
• Wavelength of radiation


  A measure of the distance between two consecutive crests or troughs in a wave.
• Ionization Energy


  The energy required to remove an electron from a neutral atom or molecule.
• Group 2 element


  An element in the second column of the periodic table, including beryllium, magnesium, calcium, strontium, barium, and radium
• Trend of decreasing ionization energies

  The pattern of decreasing ionization energies as you move down a group in the periodic table
• Orbital


  A mathematical function that describes the shape and energy of an electron in an atom.
• Repulsion


  The force that causes particles with like charges to push away from each other.
• Shielding


  The phenomenon where inner electrons in an atom shield or screen the outer electrons from the positive charge of the nucleus.
• Greater shielding


  The result of increased repulsion between electrons in a filled orbital, leading to weaker attraction of outer electrons to the nucleus.