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 outermost configuration of the most electronegative element is (a) \( \mathrm{ns}^{2} \mathrm{np}^{5} \).

Step 1: Identify the Element

The question asks for the electronic configuration of the most electronegative element. The most electronegative element is fluorine, which is found in Group 17 of the periodic table.

Step 2: Write Fluorine's Electron Configuration

The electron configuration for fluorine is determined by finding its position in the periodic table. It has 9 electrons, which are distributed as 1s² 2s² 2p⁵. The outermost configuration, which involves only the second shell, is 2s² 2p⁵.

Step 3: Compare with Given Options

The outermost configuration of fluorine, which is 2s² 2p⁵, matches the option \( \mathrm{ns}^{2} \mathrm{np}^{5} \). Therefore, the correct answer is (a) \( \mathrm{ns}^{2} \mathrm{np}^{5} \).

Key Concepts

Electronegativity

Electronegativity is an essential concept to grasp when discussing the tendency of an atom to attract electrons towards itself. It is a crucial property in understanding how atoms interact in chemical reactions.
Various factors affect electronegativity:

• **Atomic Number:** Generally, the higher it is, the greater the electronegativity, as more protons in the nucleus attract electrons more strongly.
• **Atomic Radius:** Smaller atoms tend to have higher electronegativity because their closer nuclei exert a stronger pull on electrons.

Electronegativity trends in the periodic table increase from left to right across a period and decrease down a group. The most electronegative element in the periodic table is fluorine, found in Group 17, which plays a significant role in forming polar bonds in chemical compounds.

Fluorine

Fluorine is renowned as the most electronegative element, a quality that makes it an aggressive electron acceptor in chemical reactions. Its atomic number is 9, symbolized by F, and it is a pale yellow gas at room temperature.
Here are some notable properties of fluorine:

• **High Reactivity:** Due to its electronegativity, fluorine can form bonds with almost any element. It vigorously reacts with metals and non-metals alike.
• **Electron Configuration:** The electron configuration of fluorine is 1s² 2s² 2p⁵. This configuration shows that it is one electron short of a full p-orbital, motivating its high tendency to gain an electron and complete its valence shell.

Fluorine compounds are generally highly stable, a feature exploited in many industrial applications, such as in the creation of robust, non-reactive coatings like Teflon.

Periodic Table Groups

Understanding the periodic table's groups is essential in chemistry as they highlight similar chemical behaviors within elements. Groups are the vertical columns in the periodic table, numbered from 1 to 18. Elements within the same group typically share:

• **Valence Electrons:** Elements have the same number of electrons in their outermost shell, leading to similar reactivity.
• **Chemical Properties:** Such as metals being good conductors found in groups 1 and 2, while non-metals in groups 17 and 18 are typically insulators with varying electronegativities.

Group 17, also known as the halogens, includes fluorine, chlorine, bromine, iodine, and astatine. These elements are known for their high electronegativity and reactivity, particularly with alkali metals to form salts like sodium chloride (table salt). Understanding the characteristics that define each group helps in predicting element behavior and the types of compounds they can form.