Ionization energy periodic table

Ionization energy is the electrostatic attraction that changes the trend in the groups and periods of a periodic table

Introduction to Ionization energy periodic table

Ionization energy is the minimum amount of energy required to remove an electron from the outermost orbit of an atom to the minimum distance from the atom so that no electrostatic interaction exists between the separated electron and the cation so formed.

explanation for Ionization energy from periodic table

Electrons present in an atom are attracted towards the nucleus due to the positive charge of protons. Therefore, some energy is required to remove an electron from an atom. This energy is referred to as the "Ionization Energy", as when the electron is removed from an atom, the atom is converted to a positively charged ion.
THe energy required to remove the first electron from a neutral atom is called the First Ionization energy, the energy required to remove the second electron from a positive cation is called the Second Ionization Energy, and so on.

Factors on which the ionization energy of an atom depends(periodic table)

1. Atomic size:- The greater the atomic size, the greater is the distance of the outermost shell from the protons inside the nucleus. Thus, there is lesser pull of the protons on the electrons of the last shell. Thus, the greater the atomic size, the lesser is the ionization energy of that element.
2. Nuclear charge:- Greater nuclear charge means greater attraction of the elecrons by the protons inside the nucleus. Thus, if the nuclear charge is greater, it becomes difficult to remove electrons from the outermost shell. Thus, the greater the nuclear charge, the greater is the Ionization Energy.

Varation of ionization energy in the Periodic table:-

1. Across a Period:- 
   Ionization energy of elements increases as one moves from left to right in a row of the Periodic Table.
   Reason:-As we move from left to right in a row of the Periodic Table, the number of rows in the atoms of successive elements remains the same whereas the nuclear charge increases. This causes the electrons to be attracted more strongly towards the nucleus, and hence, the ionization energy increases.
2. In a Group:-
   As one moves down a group in the Periodic Table, the ionization energy of successive elements decreases.
   Reason:-As we move down a group, the number of shells in the atoms of elements increases and the atomic number also increases. This causes an increase in the atomic size as well as in the nuclear charge. But the increase in atomic size overcomes the increase in nuclear charge, and thus it becomes more easier to remove electrons from atoms of elements as one moves down a group.