Chapter 6, Problem 87A

Solution

Interpretation: The graph between the density and the atomic number of group 15 elements needs to be plotted and the trend needs to be explained.

Concept Introduction: To plot a graph between two variables, the data given for one can be plotted at the x -axis and the other at the y -axis. The trend can be explained based on the shape of the graph obtained.

The given data for atomic number and density of the element is as follows:

Element	Atomic number	Density $\left({\text{g/cm}}^{\text{3}}\right)$
Nitrogen	7	$1.14\times {10}^{-3}$
Phosphorus	15	1.82
Arsenic	33	5.22
Antimony	51	6.53
Bismuth	83	10.05

The graph can be plotted as follows:

  

On moving from top to bottom in a group, atomic number increases and atomic radius also increases (as the new shell is added around the nucleus). Due to an increase in atomic radius, density also increases. This can also be confirmed from the plot obtained between the atomic number and density of the element. Here, Nitrogen with the lowest atomic number has the lowest density, and bismuth with the highest atomic number has the highest density.

Therefore, the trend is the density of an element increases with increasing atomic number.