Chapter 6.3, Problem 18LC

Interpretation Introduction

Interpretation:

Change in atomic size down the group and across the period is to be determined.

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 18LC

Atomic size increases down the group while decreases across the period.

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 becausewhen 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.

Whereas atomic size decreases across the period or decreases from left to right. This is because when moving left to right in the periodic table, the number of shells stays constant while the nuclear charge increases by one at each step. 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.