Ionization energy trends are exceptions to the trend.

Ionization energy is the amount of energy needed to remove an electron from a ion.The first Ei of an atom or molecule is the amount of energy needed to remove one mole of electrons.

The strength by which an electron is bound is a measure of the difficulty of removing it.The higher the energy, the harder it is to remove an electron.ionized energy is an indicator of reactivity.Ionization energy can be used to predict the strength of chemical bonds.

Ionization energy is reported in units of kJ/mol or eV.

There is a trend on the periodic table of elements.

The first ionization energy is required to remove the outermost electron from a neutral atom.The second energy is needed to remove the next electron.The second energy is always higher than the first.An alkali metal atom is an example.The atom has a stable electron shell if the first electron is removed.A new electron shell is used to remove the second electron.