Chemistry

Question Analysis
This question tests the ability to apply periodic trends to arrange elements in order of decreasing atomic radius.

Key Concept Explanation
Atomic radius generally decreases as you move from left to right across a period due to the increasing nuclear charge, which pulls the valence electrons closer to the nucleus.

Step-by-step Solution
1. Identify the elements: Mg, Al, Si, P.
2. Compare their positions in the periodic table: Mg is on the far left, followed by Al, Si, and P.
3. As you move from left to right, the atomic radius decre...