Problem 16 - A Complete Resource Book in Chemistry for JEE Main

Question

The outer most configuration of most electronegative element is (a) \(\mathrm{ns}^{2} \mathrm{np}^{5}\) (b) \(\mathrm{ns}^{2} \mathrm{np}^{6}\) (c) \(\mathrm{ns}^{2} \mathrm{np}^{4}\) (d) \(\mathrm{ns}^{2} \mathrm{np}^{6}\)

Step-by-Step Solution

Answer

The answer is (a) \(\mathrm{ns}^{2} \mathrm{np}^{5}\).

Step 1: Identify the Most Electronegative Element

Fluorine is the most electronegative element on the periodic table. We need to determine its electronic configuration to find the outermost configuration.

Step 2: Recall Fluorine's Electronic Configuration

The electronic configuration of fluorine, which has an atomic number of 9, is: \(1s^2 2s^2 2p^5\). This configuration tells us about its energy levels and subshell configurations.

Step 3: Identify the Outermost Shell Configuration

The outermost shell for fluorine is the second shell, where the configuration is \(2s^2 2p^5\). This matches with the configuration type \(\mathrm{ns}^{2} \mathrm{np}^{5}\).

Step 4: Verify Against Given Options

Compare the identified outer configuration \(\mathrm{ns}^{2} \mathrm{np}^{5}\) with the given options. Option (a) \(\mathrm{ns}^{2} \mathrm{np}^{5}\) matches the outermost electronic configuration of the most electronegative element.

Key Concepts

Most Electronegative Element

Electronegativity is a chemical property that measures an atom's ability to attract electrons towards itself when forming a chemical bond. Generally, elements with high electronegativity tend to attract electrons more strongly than elements with lower electronegativity.
Fluorine holds the title as the most electronegative element on the periodic table, having an electronegativity value of 3.98 on the Pauling scale.

• This means fluorine can attract electrons towards itself more efficiently than any other element.
• A large electronegativity indicates a high tendency to gain electrons, which emphasizes its significant reactivity, especially with metals.

Fluorine's electronegativity impacts its chemical behavior, making it a potent oxidizing agent that attracts and holds electrons tightly in various compounds.

Fluorine

Fluorine is a highly reactive, pale yellow gas at room temperature, and it's the lightest of the halogens. Its atomic number is 9, indicating nine protons in its nucleus and, in a neutral state, nine electrons.
This high reactivity comes from its small size and the high electronegativity, which allows it to forcefully attract electrons.

• Fluorine forms compounds with a wide range of elements due to its ability to achieve a noble gas configuration by accepting just one electron.
• Among numerous applications, fluorine's compounds are used in toothpaste, refrigerants, and pharmaceuticals.

Despite its reactive nature, when bonded in compounds, fluorine stabilizes and interacts to form stable materials like Teflon.

Outermost Configuration

The electronic configuration of an element provides insight into the arrangement of electrons around its nucleus, denoting the energy levels and subshells occupied by these electrons.
Understanding the outermost configuration is crucial, as it influences an element's chemical properties, such as reactivity and bonding.

• For fluorine, the electronic configuration is expressed as: \(1s^2 2s^2 2p^5\).
• The outermost shell configuration for fluorine is \(2s^2 2p^5\), which matches the generic formula \(\mathrm{ns}^2 \mathrm{np}^5\).

This configuration implies that fluorine has 7 valence electrons, meaning it needs just **one** more electron to achieve a full octet, making it highly reactive.

Periodic Table

The periodic table is an organized chart of chemical elements, historically designed by Dmitri Mendeleev.
Elements are arranged based on increasing atomic number, which also correlates with their electronic configurations and recurring chemical properties.

• Elements in the same group (vertical columns) share a similar outer electronic shell configuration, thus displaying similar chemical behavior.
• Fluorine is located in Group 17 (halogens) and Period 2, marking it among the most reactive nonmetals.

The periodic table not only provides a simple, visual representation of elemental characteristics but also serves as a crucial tool in predicting how different elements will interact chemically based on their electronic configuration and position in the table.