Electron Affinity Group 13
Ionization Energy and Electron Affinity
Ionization Energy is removing an electron
Electron Affinity is adding an electron
Ionization Energy
• Energy required to remove an electron from a ground state atom
Ionization Energy of Noble Gases
• Noble gases have full orbitals, so it is difficult to remove an electron from them. But, it does become easier the further away the electrons get from the nucleus.
Ionization Energy of Alkali Metals
• Alkali Metals only have one valence electron, so it does not take much effort to remove that one electron.
• When it is removed, they achieve Noble Gas Configuration.
Dips in Ionization Energy
• There are dips at Group 2 and Group 15.
• Group 2 is because it has a full s- orbital and thus has a bit more stability. Group 15 has a half-filled orbital.
Electron Affinity
• Amount of energy released when an atom adds an electron
• Another way to say it is;
– How much does an atom want another electron?
Electron Affinity of Noble Gases
• Noble Gases have no electron affinity because they already have full orbitals and will not take any more…
We will ignore transition metals for now
Trends in Electron Affinity
• The trend is to increase as you go right across the Periodic
Table because there are more protons in the nucleus to attract them…
Trends in Electron Affinity
• The trend is to decrease as you go down the Periodic Table because the electrons are further from the nucleus.
Exceptions in Electron Affinity
• Notice how the Alkaline Earth and Nitrogen Group break the trend? Why do you think that is?
Remember, this is related to how much they want to add electrons.
Why would the Carbon Family have more electron affinity than the Boron or Nitrogen Families?
Because if Carbon added one more electron, it would have
3 electrons in the p- orbital
Half-filled orbitals are more stable than other states other than completely full
Exceptions in Electron
Ionization Energy is removing an electron
Electron Affinity is adding an electron
Ionization Energy
• Energy required to remove an electron from a ground state atom
Ionization Energy of Noble Gases
• Noble gases have full orbitals, so it is difficult to remove an electron from them. But, it does become easier the further away the electrons get from the nucleus.
Ionization Energy of Alkali Metals
• Alkali Metals only have one valence electron, so it does not take much effort to remove that one electron.
• When it is removed, they achieve Noble Gas Configuration.
Dips in Ionization Energy
• There are dips at Group 2 and Group 15.
• Group 2 is because it has a full s- orbital and thus has a bit more stability. Group 15 has a half-filled orbital.
Electron Affinity
• Amount of energy released when an atom adds an electron
• Another way to say it is;
– How much does an atom want another electron?
Electron Affinity of Noble Gases
• Noble Gases have no electron affinity because they already have full orbitals and will not take any more…
We will ignore transition metals for now
Trends in Electron Affinity
• The trend is to increase as you go right across the Periodic
Table because there are more protons in the nucleus to attract them…
Trends in Electron Affinity
• The trend is to decrease as you go down the Periodic Table because the electrons are further from the nucleus.
Exceptions in Electron Affinity
• Notice how the Alkaline Earth and Nitrogen Group break the trend? Why do you think that is?
Remember, this is related to how much they want to add electrons.
Why would the Carbon Family have more electron affinity than the Boron or Nitrogen Families?
Because if Carbon added one more electron, it would have
3 electrons in the p- orbital
Half-filled orbitals are more stable than other states other than completely full
Exceptions in Electron