Chapter 11, Problem 12STP

Interpretation Introduction

Interpretation:The false statement for the behavior of ionization energy across a row of periodic table needs to be determined.

Concept interpretation:Ionization energy is the amount of energy required to remove an electron from an outer shell of atom.

Answer to Problem 12STP

Across a row of the periodic table, smaller atoms generally have smaller ionization energies is a false statement.

Explanation of Solution

Ionization energy of an atom increases left to right in a period because the electrons are held tighter and have higher effective nuclear charge. The effective nuclear charge is higher due to increase in number of electrons in the same shell. For example, sodium and magnesium both lies in same period but magnesium has higher 1^st ionization energy due to higher number of electron and higher charge and both have 3 shells.

Conclusion

As one move across a period in periodic table the ionization energy increases because the electrons are much tightly packed to the nucleus due to high effective nuclear charge.

As we move from top to bottom in the periodic table, the atomic radius or atomic size increases and the ionization energy decreases this is due to addition of an extra shell and results in increasing atomic radius.