Question

which of these would best describe the structural difference between magnesium and aluminum? a magnesium has one more proton than aluminum. b magnesium has one less proton than aluminum. c magnesium’s atomic mass is larger than aluminum’s. d aluminum has more protons and fewer neutrons than magnesium.

Explanation:

1. Recall atomic number (protons) and atomic mass (protons + neutrons) from the periodic table. Magnesium (Mg) has atomic number 12, aluminum (Al) has atomic number 13. So Mg has 12 protons, Al has 13 protons.
2. Analyze option A: Mg has 12 protons, Al 13—so Mg has 1 less, not 1 more. Eliminate A.
3. Analyze option B: Mg (12 protons) has 1 less proton than Al (13 protons). This matches.
4. Analyze option C: Mg’s atomic mass (≈24.305) is less than Al’s (≈26.982). Eliminate C.
5. Analyze option D: Al has more protons (13 vs 12), but Al’s atomic mass (26.982) and Mg’s (24.305) imply Al has more neutrons (26.982 -13 ≈14; 24.305 -12≈12.3), so Al has more neutrons, not fewer. Eliminate D.

Answer:

B. Magnesium has one less proton than aluminum.