Which of the following elements exhibits the greatest metallic character and is therefore the most chemically active metal?

• A. Na
• B. Al
• C. Mg
• D. K

Answer: (D)

Verified step by step guidance

1. Understand that metallic character refers to how readily an element can lose electrons to form positive ions, which is related to its position on the periodic table.
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 (Na, Al, Mg) by their positions: all are in period 3, with Na and Mg being metals and Al a metalloid, but the problem states the correct answer is K, which is in period 4 and group 1, below Na.
5. Conclude that potassium (K), being below sodium (Na) in group 1, has a greater metallic character and is more chemically active because it loses its outer electron more easily due to increased atomic size and shielding.