Chapter 7, Problem 50A

Interpretation Introduction

Interpretation:

The importance of ionization energy and electron affinity in the formation of ions needs to be explained.

Concept introduction:

Ionization energy: It is the energy required to remove electrons from an atom. In other words, it defines if the atom is ready to give up electron. Mostly electrons are lost when the atom is in its ground state.

Electron affinity: It is the amount of energy released when an electron is taken up by the atom to form negative ion.

Answer to Problem 50A

If ionization energy is low, then atoms will lose electrons easily. If electron affinity is high, then atoms will gain electrons easily.

Explanation of Solution

The energy required to remove the outermost electrons is termed as ionization energy or IE. When looking at the periodic table, it can be noticed that the atomic size decreases as we go across the period. But the atomic number increases with decreased diameter which means that forces of attraction between the nucleus and electrons is more. Hence, it is difficult to remove the electrons. This indicates that ionization energy increases as we go from left to right of the periodic table. But if we go down the group, the atomic size increases. This implies that force of attraction between the nucleus and outermost electrons decreases wherein electrons can be removed easier. Hence, ionization energy decreased down the group.

Electron affinity is the energy released when electrons is added to the atom. When we go across the period, the electron affinity increases implying that the atomic size is less having more influence on the outermost electrons. When we go down the group, the atomic size increases and hence the central nuclei will not have much influence on the electrons. This causes decrease in the electron affinity down the group.

Conclusion

If ionization energy is low, then atoms will lose electrons easily. If electron affinity is high, then atoms will gain electrons easily.