Problem 104 - A Complete Resource Book in Chemistry for JEE Main

Question

The electronic configurations of four elements are given below: (1) \(1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{5}\) (2) \(1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{4}\) (3) \(1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{3}\) (4) \(1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2} 3 \mathrm{p}^{4}\) Which of the following arrangements gives the correct order in terms of increasing electronegativity of the elements? (a) \(3<2<4<1\) (b) \(2>3>1>4\) (c) \(4<3<2<1\) (d) \(\mathrm{k}<2<3<4\)

Step-by-Step Solution

Answer

Option (c) \(4 < 3 < 2 < 1\) is the correct arrangement.

Step 1: Identify the Elements

To find the correct order of increasing electronegativity, first identify the elements based on their electronic configurations. 1. **Element 1**: Configuration - \(1s^2 2s^2 2p^5\), which corresponds to Fluorine (\(F\)).2. **Element 2**: Configuration - \(1s^2 2s^2 2p^4\), which corresponds to Oxygen (\(O\)).3. **Element 3**: Configuration - \(1s^2 2s^2 2p^3\), which corresponds to Nitrogen (\(N\)).4. **Element 4**: Configuration - \(1s^2 2s^2 2p^6 3s^2 3p^4\), which corresponds to Sulfur (\(S\)).

Step 2: Determine Electronegativity Values

Electronegativity decreases down a group and increases across a period from left to right. Using this periodic trend:- Fluorine (\(F\)) has the highest electronegativity value.- Oxygen (\(O\)) is less than Fluorine.- Nitrogen (\(N\)) is less than Oxygen.- Sulfur (\(S\)) is further down the group from Oxygen, so it has the lowest electronegativity of these elements.

Step 3: Arrange Elements by Electronegativity

Using their electronegativity values:Fluorine (\(F\)) > Oxygen (\(O\)) > Nitrogen (\(N\)) > Sulfur (\(S\)).So, the order of increasing electronegativity is Sulfur (\(3\)), Nitrogen (\(2\)), Oxygen (\(4\)), Fluorine (\(1\)).

Step 4: Select the Correct Option

The increasing order of electronegativity based on step 3 is:**(c) \(4 < 3 < 2 < 1\)**This matches with option (c).

Key Concepts

Electronic Configuration

Understanding electronic configuration is vital when studying elements. It tells us how electrons are distributed in an atom's shell or orbitals. Each element has a distinct configuration represented by numbers and letters. For example, the configuration can look like this: \(1s^2 2s^2 2p^5\), as seen with Fluorine in the exercise.

• The numbers denote the shell or energy level: 1, 2, 3, etc.
• The letters (s, p, d, f) describe the type of orbital in the shell.
• Superscripts show how many electrons are present in that particular orbital.

This configuration helps us to identify the element and understand its chemical properties. It's like the element's fingerprint that distinguishes it from others. Recognizing these fingerprints enables us to map each element's position in the periodic table and comprehend its reactivity, stability, and other chemical properties.

Periodic Table

The periodic table is an organized catalog of elements, arranged by increasing atomic number and recurring chemical properties. It showcases periodic trends, including electronegativity, atomic and ionic size, ionization energy, and more.
Each row in the periodic table corresponds to a period, where as we move from left to right across a period, electronegativity generally increases. Each column represents a group, where elements share similar valence electron configurations.
Understanding the periodic table is crucial in determining element characteristics, as evident in the exercise. By leveraging periodic trends, we can predict and explain the reactivity and interactions between different elements. The table itself is like a giant chemistry cheat sheet that guides our understanding of elemental behavior and chemical bonding.

Element Identification

Element identification through electronic configuration allows us to understand various elements better. Each configuration aligns with a specific element, revealing important properties like electronegativity and reactivity.
For instance, in the exercise, we identify Fluorine, Oxygen, Nitrogen, and Sulfur based on their configurations. Recognizing these helps explain why Fluorine has the highest electronegativity and Sulfur the lowest among them.

• Fluorine: \(1s^2 2s^2 2p^5\)
• Oxygen: \(1s^2 2s^2 2p^4\)
• Nitrogen: \(1s^2 2s^2 2p^3\)
• Sulfur: \(1s^2 2s^2 2p^6 3s^2 3p^4\)

Identifying elements ensures accurate insights into how they might attract electrons during bonds, react in chemical environments, and fit into the larger picture of periodic trends. It's like solving a puzzle, where once pieces are correctly placed, the full picture of atomic chemistry emerges.