Periodic Table Trends in Metallic Character

Steps:

• Recall that metallic character increases with more valence electrons and larger atomic size, favoring left-side placement.
• Evaluate A: Left-side elements (low electronegativity) donate electrons easily, unlike right-side nonmetals.
• Check B: Ionization energy decreases down a group, so top elements hold electrons tighter.
• Verify C and D: Groups share valence electrons but vary in shell count; periods share shell number but vary in outer electrons.

Why A is correct:

• Metallic character decreases across a period due to increasing nuclear charge pulling electrons closer, making left-side elements more likely to lose electrons (per periodic law trends).

Why the others are wrong:

• B: Down a group, atomic size increases, reducing ionization energy, so bottom elements lose electrons more readily.
• C: Elements in the same group have increasing numbers of completed inner shells down the group.
• D: Elements in the same period fill the outer shell progressively, so outer electrons vary by group.

Final answer: A