Final answer:
The atomic radius of an element increases as we move down a group in the periodic table due to the addition of electron shells. Among the given options, potassium with the electron configuration 1s²2s²2p⁶3s²3p⁶4s¹ has a larger atomic radius than calcium with the configuration [Ar]4s². The correct answer is option: D. 1s²2s²2p⁶3s²3p⁶4s¹
Step-by-step explanation:
Comparing the atomic radii of different elements based on their electron configurations, it is notable that as we move down a group in the periodic table, the atomic radius increases due to the addition of new electron shells. As for the given electron configurations:
- 1s²2s²2p⁶3s²3p³ represents phosphorus,
- 1s²2s²2p⁶3s¹ represents sodium,
- 1s²2s²2p⁶3s²3p⁴3p⁵ represents chlorine,
- 1s²2s²2p⁶3s²3p⁶4s¹ represents potassium.
Potassium (K) has a larger atomic radius than calcium (Ca) because it is in the same period but has one more electron shell. The electron configuration of potassium, 1s²2s²2p⁶3s²3p⁶4s¹, thus will have a larger atomic radius than the configuration of calcium, which is [Ar]4s² or 1s²2s²2p⁶3s²3p⁶4s².