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

• A. Na
• B. K
• C. Al
• D. Mg

Answer: (B)

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. Identify the elements given: Na (Sodium) and K (Potassium) are in Group 1 (alkali metals), while Al (Aluminum) and Mg (Magnesium) are in Groups 13 and 2 respectively, which are less metallic than Group 1 elements.
4. Compare Na and K, both in Group 1, but K is below Na in the periodic table, meaning K has a larger atomic radius and lower ionization energy, so it exhibits greater metallic character and reactivity.
5. Conclude that among the options, K exhibits the greatest metallic character and is the most reactive metal because it is the lowest Group 1 element listed.