Periodic trends for superheavy alkali metal

Steps:

• Place element 119 in Group 1, Period 8, as the next alkali metal after francium.
• Apply Group 1 trends: increasing atomic radius down the group due to added electron shells.
• Assess ionization energy trend: alkali metals have low values, decreasing down the group, unlike noble gases.
• Evaluate orbital configuration: Group 1 ends in ns¹, but relativistic effects in Period 8 may alter stability.

Why B is correct:

• Atomic radius increases down Group 1 as the principal quantum number rises, adding shells; thus, Period 8 element 119 exceeds the seven existing Group 1 elements (H to Fr).

Why the others are wrong:

• A: Relativistic effects in superheavy elements destabilize the 8s orbital, making the outermost electrons involve p or d contributions, not purely s.
• C: Group 1 elements have low first ionization energies due to easy ns¹ loss; element 118 (noble gas) has higher IE from stable configuration.
• D: Not enough information.

Final answer: B