Which of the following period 4 elements is most likely to lose electrons and form a cation?

• A. Se (selenium)
• B. Br (bromine)
• C. Ge (germanium)
• D. K (potassium)

Answer: (D)

Verified step by step guidance

1. Identify the elements given and their positions in period 4 of the periodic table: Se (selenium), Br (bromine), Ge (germanium), and K (potassium). Note that K (potassium) is actually in period 4 but was not listed initially in the options.
2. Recall that elements on the left side of the periodic table (metals) tend to lose electrons and form cations, while elements on the right side (nonmetals) tend to gain electrons and form anions.
3. Determine the group number and general properties of each element: K is an alkali metal in group 1, Ge is a metalloid in group 14, Se is a nonmetal in group 16, and Br is a halogen in group 17.
4. Understand that alkali metals like K have a single electron in their outermost shell, which they can lose easily to form a +1 cation, making them highly likely to lose electrons compared to the other elements listed.
5. Conclude that among the given elements, K (potassium) is the most likely to lose electrons and form a cation because of its position as an alkali metal with low ionization energy.