Question

The atomic radius in pm of Mg, P, Si, Al respectively is:

• A. \( 160, 143, 117, 110 \)
• B. \( 110, 117, 143, 160 \)
• C. \( 160, 110, 117, 143 \)
• D. \( 110, 160, 143, 117 \)

Hint:

Understanding the relationship between electron configuration and effective nuclear charge is crucial when determining atomic sizes in the periodic table.

Answer 1

The Correct Option is C

The correct answer is (3) 160, 110, 117, 143.
Trend in Atomic Radii Across a Period
Atomic radii generally decrease as you move from left to right across a period in the periodic table. This is due to the increasing nuclear charge, which pulls the electrons closer to the nucleus.
Trend in Atomic Radii Down a Group
Atomic radii generally increase as you move down a group in the periodic table. This is because the number of electron shells increases, placing the outermost electrons farther from the nucleus.
Applying the Trend to Mg, P, Si, and Al
Mg (Magnesium): Group 2, Period 3
P (Phosphorus): Group 15, Period 3
Si (Silicon): Group 14, Period 3
Al (Aluminum): Group 13, Period 3
Since all four elements are in the same period (Period 3), we expect the atomic radius to decrease from left to right:
Mg > Al > Si > P
Therefore, the correct order of atomic radii is 160 pm (Mg), 110 pm (Al), 117 pm (Si), 143 pm (P).

Answer 2

To solve this problem, we need to know the atomic radii of the elements magnesium (Mg), phosphorus (P), silicon (Si), and aluminum (Al).

1. Atomic Radii Trend:
The atomic radius generally decreases across a period from left to right and increases down a group. Based on this trend and the known atomic radii of these elements:

• Magnesium (Mg), an alkaline earth metal, has the largest atomic radius.
• Phosphorus (P), a non-metal, has a smaller atomic radius than magnesium but larger than silicon.
• Silicon (Si) comes next, with a smaller atomic radius compared to phosphorus.
• Aluminum (Al), being a metal, has the smallest atomic radius of these elements.

2. Analyzing the Options:
Option 1: 160, 143, 117, 110 (incorrect order).
Option 2: 110, 117, 143, 160 (incorrect order).
Option 3: 160, 110, 117, 143 (correct order).

This follows the atomic radius trend correctly, with magnesium having the largest atomic radius, followed by aluminum, silicon, and phosphorus
Option 4: 110, 160, 143, 117 (incorrect order).

3. Conclusion:
Based on the correct atomic radius order for these elements, the correct answer is Option C.

Final Answer:
The correct answer is Option C: 160, 110, 117, 143.