Question

Among the following pairs of atomic numbers, the pair which belongs to \(p\) -block is (1) 8,16 (2) 4,8 (3) 6,12 (4) 12,24

Short answer

(1) 8, 16

Step-by-step solution

Understanding the p-block

The p-block elements in the periodic table are those elements where the last electron enters any of the three p orbitals. These elements are found in groups 13-18.

Identify the atomic numbers

Examine the given atomic numbers in each pair to determine if they fall within the p-block elements. Use the periodic table for reference.

Evaluate pair 1 (8, 16)

Atomic number 8 corresponds to oxygen and atomic number 16 corresponds to sulfur. Both oxygen and sulfur are in the p-block (group 16).

Evaluate pair 2 (4, 8)

Atomic number 4 corresponds to beryllium and atomic number 8 corresponds to oxygen. Beryllium is in the s-block (group 2), while oxygen is in the p-block.

Evaluate pair 3 (6, 12)

Atomic number 6 corresponds to carbon and atomic number 12 corresponds to magnesium. Carbon is in the p-block (group 14), but magnesium is in the s-block (group 2).

Evaluate pair 4 (12, 24)

Atomic number 12 corresponds to magnesium and atomic number 24 corresponds to chromium. Both magnesium and chromium are in the s-block and d-block respectively. Neither is in the p-block.

Conclusion

Based on the analysis, the correct pair belonging to the p-block is (1) 8, 16.

Key concepts

Periodic Table Groups

The periodic table is divided into vertical columns known as groups. There are 18 groups in total. Each group shares similar properties because elements in the same group have the same number of electrons in their outermost shell.
For example:

• Group 1 elements are known as alkali metals.
• Group 2 elements are known as alkaline earth metals.
• Groups 13-18 are referred to as the p-block elements.

The p-block is unique because it includes metals, nonmetals, and metalloids. Knowing the groups helps us understand the chemical behavior of the elements.
In specific, groups 13-18 contain elements that fill their p orbitals with electrons. This makes them very significant in various chemical reactions and bonding structures.

Atomic Numbers

The atomic number of an element is the number of protons in the nucleus of an atom. It also equals the number of electrons in a neutral atom. Atomic numbers are unique to each element and determine an element's position in the periodic table.
For example:

• Oxygen has an atomic number of 8.
• Carbon has an atomic number of 6.
• Magnesium has an atomic number of 12.

In our solution, understanding the atomic numbers helped identify which pairs belonged to the p-block. For pair (8, 16), both elements oxygen and sulfur fit into the p-block as both have their last electrons entering the p orbital.
Your ability to identify atomic numbers and their positions in the periodic table is essential in predicting and understanding chemical properties.

Electron Configuration

Electron configuration refers to the distribution of electrons of an atom in orbitals around its nucleus. The configuration follows the principle of filling lower energy levels first before moving to higher ones, guided by the Aufbau Principle, Pauli-Exclusion Principle, and Hund's Rule.
The order in which electrons fill up orbitals is:

• 1s
• 2s, 2p
• 3s, 3p, 4s
• 3d, 4p, 5s etc.

The p-block elements specifically are those where the last electron enters a p orbital. For example:

• Oxygen (Atomic number 8): 1s² 2s² 2p⁴
• Sulfur (Atomic number 16): 1s² 2s² 2p⁶ 3s² 3p⁴

Both oxygen and sulfur follow this pattern, confirming their place in the p-block. Proper knowledge of electron configuration is crucial for understanding the chemical behavior, reactivity, and bonding of elements.