Which atom has a larger atomic radius: sodium (Na) or chlorine (Cl)?

• A. Chlorine (Cl)
• B. Sodium (Na)

Answer: (B)

Verified step by step guidance

1. Recall that atomic radius generally decreases across a period from left to right on the periodic table due to increasing nuclear charge pulling electrons closer to the nucleus.
2. Identify the positions of sodium (Na) and chlorine (Cl) on the periodic table: both are in the same period (Period 3), with sodium on the far left and chlorine towards the right.
3. Understand that sodium has fewer protons than chlorine, so its nucleus exerts less pull on the electrons, resulting in a larger atomic radius.
4. Recognize that chlorine has more protons, which increases the effective nuclear charge, pulling its electrons closer and decreasing its atomic radius.
5. Conclude that sodium (Na) has a larger atomic radius than chlorine (Cl) because it is located to the left in the same period, where atoms are generally larger.