Graph Analysis: Periodic Properties

The graph shows a decreasing trend followed by an increase, forming a "V" shape pattern. This pattern is characteristic of properties that decrease down a group but show an anomaly at a particular element.

Step 1: Analyze the Pattern

The graph shows values decreasing from first to second element, then increasing for subsequent elements. This indicates an exception to the general periodic trend.

Step 2: Compare with Known Periodic Properties

Among the options:

• Electron affinity of group 16 elements: Shows decrease from O to S, then regular decrease
• Electron affinity of group 17 elements: Shows decrease from F to Cl, then regular decrease
• Lewis basic nature of group 15 hydrides: Shows decrease from NH₃ to PH₃, then increase
• Bond energy of halogens: Shows irregular pattern but not exactly V-shaped

Step 3: Identify the Correct Property

The V-shaped pattern matches perfectly with the Lewis basic nature of group 15 hydrides:

NH₃ > PH₃ < AsH₃ < SbH₃ < BiH₃

This anomaly occurs due to the small size and high electronegativity of nitrogen in NH₃.

Final Answer

Lewis basic nature of group 15 hydride is the property related to the given graph.

Related Topics

• Periodic trends in chemical properties
• Anomalous behavior of first elements in groups
• Lewis acid-base concept
• Hydrides of p-block elements

Key Formulae and Theory

Lewis basicity is the ability to donate an electron pair. For group 15 hydrides:

Basicity ∝ $\frac{1}{\mathrm{size}\text{ of central atom}}$

However, NH₃ shows exceptional basicity due to:

• Small size leading to high electron density
• High electronegativity difference with hydrogen
• Availability of lone pair on nitrogen

The basic strength order is: NH₃ > PH₃ < AsH₃ < SbH₃ < BiH₃