Periodic trends in metallic character

Steps:

• Recall metallic character trend: increases left to right across a period due to decreasing electronegativity and ionization energy.
• Evaluate A: Matches trend as left-side elements (low electronegativity) behave more like metals.
• Check B: Ionization energy decreases down a group, so lower elements lose electrons more readily—opposite of B.
• Verify C and D: Groups share valence electrons; periods share shells but vary in valence electrons.

Why A is correct:

• Metallic character decreases across a period per the periodic law, as increasing effective nuclear charge holds electrons tighter on the right.

Why the others are wrong:

• B: Lower group elements have lower ionization energies, losing electrons more easily.
• C: Lower elements add more electron shells, not the same number.
• D: Same-period elements share principal quantum number (shells) but have varying outer-shell electrons.

Final answer: A