To determine first ionization energy, one must know the element being used. First ionization energy shows periodically through the table of elements in a repetitive pattern. First ionization energy is the amount of energy required to remove an electron from one mole of gaseous atoms to produce one mole of gaseous ions with a positive charge.
- Find the charge of the nucleus
The more protons there are in the nucleus, the stronger the attraction of the electrons. Therefore, a greater first ionization energy is needed as the nucleus becomes more positively charged.
- Find the distance between the electron and the nucleus
No matter the charge of a nucleus, if the electron is far enough away, its attraction is much weaker; thus, the first ionization energy is smaller.
- Determine the location of the electron
Electrons in the outer layer feel a smaller net pull than one in the inner layer, and therefore, they require a smaller ionization energy. This is because the inner layer of electrons shields the outer electrons from the attraction of the nucleus.
- Determine whether it is a single or paired electron
Paired electrons actually require less energy to remove than a single electron because they tend to repulse each other.