Problem 29 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

In the long form of the periodic table, the valence shell electronic configuration of \(5 s^{2} 5 p^{4}\) corresponds to the element present in : (a) Group 16 and period 6 (b) Group 17 and period 6 (c) Group 16 and period 5 (d) Group 17 and period 5

Step-by-Step Solution

Answer

(c) Group 16 and period 5

Step 1: Understand the Given Electronic Configuration

The given electronic configuration is \(5s^2 5p^4\). This means the outermost electrons fill the 5s and 5p subshells, with 6 electrons in total (2 in 5s and 4 in 5p).

Step 2: Determine the Group Number

The group number for p-block elements is calculated by adding 10 to the total number of electrons in the p orbital. Here, 4 electrons occupy the p orbital, so the group number is \(10 + 4 = 16\). Therefore, the element belongs to Group 16.

Step 3: Determine the Period Number

The highest principal quantum number in the electronic configuration (in this case, 5) indicates the period number. Thus, the element is in Period 5.

Step 4: Match to the Correct Option

From the previous steps, we have an element in Group 16 and Period 5. Compare this with the provided options: - (a) Group 16 and period 6 - (b) Group 17 and period 6 - (c) Group 16 and period 5 - (d) Group 17 and period 5 The correct option is (c) Group 16 and period 5.

Key Concepts

Valence Shell Electronic Configuration

The concept of valence shell electronic configuration is crucial to understanding where an element sits on the periodic table. Valence electrons are the electrons present in the outermost shell of an atom. These electrons play a key role in chemical bonding and reactivity. In our exercise, the configuration is given as \(5s^2 5p^4\). This tells us:

• The principal quantum number is 5, indicating the valence shell is the fifth shell.
• There are 2 electrons in the 5s subshell and 4 electrons in the 5p subshell.

Adding these together, the element has a total of 6 valence electrons. These electrons determine how the element will react with others and are used to infer the element's placement in the periodic table.

Group Number Determination

To determine the group number of an element with a valence shell electronic configuration that ends in \(p\) orbitals, a simple rule is used. Add 10 to the number of electrons in the \(p\) subshell:

• In this exercise, the \(5p^4\) means there are 4 electrons in the \(p\) subshell.
• To find the group number for \(p\)-block elements, calculate \(10 + 4 = 16\).

Thus, the element belongs to Group 16. This group comprises elements known for forming compounds with oxygen, like sulfur and selenium, which are found in this group due to having similar valence shells and properties.

Period Number Determination

Determining the period number is straightforward if you know the principal quantum number of the outermost shell. In electron configurations such as \(5s^2 5p^4\), the principal quantum number is the number in front of the letter 's' or 'p', indicating the shell number, which is 5 in this case. Hence, the period is 5.
The period number helps identify the energy level of the valence shell, which is crucial for understanding trends in the periodic table. Elements placed in the same period have the same highest energy level, indicating that they have similarities in terms of electron energy levels, despite differences in chemical properties.