Question

The factors that influence the ionization energies are:

A.The size of atom
B.The charge on nucleus
C.How effectively the inner shell electron screen the nuclear charge
D.All of the above

Answer 1

The ionization energy of an atom is energy required to remove an electron from the valence shell of an atom. Ionization energy of an atom depends on the force of attraction between the electron and nucleus of the atom and this force depends on many factors or properties of the atom.

Complete step by step answer:
We know that ionization energy depends on the force of attraction between negatively charged electrons and positively charged nuclei. This force depends upon:
The size of atom: The force of attraction is the electrostatic force of attraction which depends on charge and distance. We know that electrostatic force is inversely proportional to distance between charge particles. Means if the size of the atom is smaller than the force of attraction it is strong and ionization energy is high. Or if size is large then ionization energy is less and electrons can be removed easily from atoms.
Effective nuclear charge $\left( {{Z_{eff}}} \right)$: Electrostatic force is directly proportional to charge on particles. Then ionization energy also depends on the charge on the nucleus and ionization energy increases with increase in nuclear charge between the outermost electron and nucleus.
Screening effect: Screening effect is the effect created due to screen nuclear force on the outermost electron and nucleus by inner shell electrons. Basically, the inner shell electron reduces the effect of the nucleus on the outermost electron and decreases the ionization energy of an atom.

Hence all the options A, B and C are correct so the correct answer is option D i.e all of the above.

Note: Screening effect is mainly observed in atoms with large atomic numbers because they have a large number of electrons in the inner shell due to which screening is large and decreases the ionization energy. We can remove more than one electron from an atom but ionization energy is increasing with a large factor with removal of electrons from an atom.