Which of the following sequences correctly represents the trend in atomic radius size for the elements Na, Mg, and Al in the same period?

• A. Na = Mg = Al
• B. Na > Mg > Al
• C. Mg > Na > Al
• D. Al > Mg > Na

Answer: (B)

Verified step by step guidance

1. Recall that atomic radius generally decreases from left to right across a period in the periodic table due to increasing nuclear charge attracting the electrons more strongly.
2. Identify the elements Na (Sodium), Mg (Magnesium), and Al (Aluminum) as consecutive elements in the same period (Period 3).
3. Understand that as you move from Na to Mg to Al, the number of protons in the nucleus increases, which pulls the electron cloud closer, reducing the atomic radius.
4. Therefore, the atomic radius trend should show the largest radius for Na, smaller for Mg, and smallest for Al.
5. Conclude that the correct sequence representing the trend in atomic radius size is: \(\text{Na} > \text{Mg} > \text{Al}\).