Chapter 6, Problem 61A

(a)

Interpretation Introduction

Interpretation: The trend in atomic size with group 1 is to be explained.

Concept introduction:

The periodic table is a columnar structure that organizes different elements into groups based on how they behave. The elements in the periodic table of today are ordered according to the periodic law. The elements are organized in the modern periodic table in increasing order of their atomic number. When elements are arranged in increasing order of atomic number, periodic trends are observed in certain properties.

Answer to Problem 61A

Atomic size increases down the group.

Explanation of Solution

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. 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, the atomic size of the group 1 element increases down the group.

(b)

Interpretation Introduction

Interpretation: The difference between the size of atoms and the size of ions is to be explained.

Concept introduction:

The periodic table is a columnar structure that organizes different elements into groups based on how they behave. The elements in the periodic table of today are ordered according to the periodic law. The elements are organized in the modern periodic table in increasing order of their atomic number. When elements are arranged in increasing order of atomic number, periodic trends are observed in certain properties.

Answer to Problem 61A

The cationic size is smaller than the atomic size due to an increased inward pull.

Explanation of Solution

Cations are always smaller than their parent atom. This is because the number of protons remains the same, but the number of electrons decreases. Now, the outermost electron is more tightly held by the nucleus which leads to an increase in inward pull. So, the ionic size of cations is always smaller than the atomic size.