Question

based on electron configuration, which atom has the greatest radius? ar4s^2 ne3s^23p^5 ne3s^23p^4 ne3s^23p^3

Explanation:

Step1: Recall atomic - radius trends

Atomic radius generally decreases across a period and increases down a group. For elements with the same principal - quantum number ($n$) for the outermost electrons, the greater the number of protons in the nucleus, the smaller the atomic radius due to the increased effective nuclear charge pulling the electrons inwards.

Step2: Analyze electron configurations

The electron configurations are:

• $[Ar]4s^{2}$ represents calcium (Ca) with 20 protons and 4 energy levels.
• $[Ne]3s^{2}3p^{5}$ represents chlorine (Cl) with 17 protons and 3 energy levels.
• $[Ne]3s^{2}3p^{4}$ represents sulfur (S) with 16 protons and 3 energy levels.
• $[Ne]3s^{2}3p^{3}$ represents phosphorus (P) with 15 protons and 3 energy levels.

Step3: Compare atomic radii

Since Ca has electrons in the 4th energy level while Cl, S, and P have electrons in the 3rd energy level, Ca has the largest atomic radius among the given elements.

Answer:

$[Ar]4s^{2}$