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).