Based on periodic trends in metallic character, which of the following elements is expected to be the most reactive metal?

• A. Mg
• B. Na
• C. Al
• D. K

Answer: (D)

Verified step by step guidance

1. Understand that metallic character refers to how readily an element loses electrons to form positive ions, which is closely related to reactivity in metals.
2. Recall that metallic character increases as you move down a group (column) in the periodic table because atoms have more electron shells, making it easier to lose outer electrons.
3. Recall that metallic character decreases as you move from left to right across a period (row) because atoms have more protons pulling electrons closer, making it harder to lose electrons.
4. Compare the given elements: Mg (magnesium) and Al (aluminum) are in period 3, with Mg to the left of Al, so Mg is more metallic than Al; Na (sodium) is also in period 3 but to the left of Mg, so Na is more metallic than both Mg and Al.
5. Recognize that K (potassium), which is not listed but mentioned as the correct answer, is in period 4 and group 1, below Na, so it has even greater metallic character and reactivity than Na, Mg, or Al.