Chapter 6, Problem 52A

Interpretation Introduction

Interpretation:

It is to be explained why fluorine is smaller than oxygen and chlorine.

Concept Introduction :

Periodic trends are patterns found in the periodic table that show several facets of a particular element. A periodic trend is observed in atomic size also. Atomic size increases down the group.

Explanation of Solution

Fluorine and oxygen are present in the same period and so have the same number of shells. However, because oxygen only has 8 protons pulling those outer electrons, fluorine has 9 protons, which will tend to make F slightly smaller in radius than O. The number of shells stays constant in F and O while the nuclear charge increases by one. As nuclear charge increases, electrons in the outermost shell are drawn to it with increasing force, which causes the size of atoms to gradually shrink over time.

Chlorine and fluorine are present in group 17 and chlorine is placed below fluorine. Down the group atomic size decreases. This is because when moving from top to bottom in the group, both the number of shells and nuclear charge increase. The effect of more shells, however, outweighs the effect of a higher nuclear charge which increases atomic radius.

Thus, fluorine has a smaller radius than oxygen and chlorine.