Why might arsenic be able to substitute for phosphorus in polyatomic ions?

• A. Arsenic forms only monatomic ions, unlike phosphorus.
• B. Arsenic and phosphorus have similar atomic radii and chemical properties.
• C. Arsenic has a much higher electronegativity than phosphorus.
• D. Arsenic is a transition metal, while phosphorus is a nonmetal.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the concept of substitution in polyatomic ions. Substitution occurs when one element can replace another in a compound without significantly altering the compound's structure or properties.
2. Step 2: Compare the positions of arsenic and phosphorus in the periodic table. Both elements are in the same group (Group 15), which means they have similar valence electron configurations.
3. Step 3: Recognize that similar valence electron configurations lead to similar chemical properties, such as bonding behavior and oxidation states.
4. Step 4: Consider atomic radii. Arsenic and phosphorus have comparable atomic sizes, which allows arsenic to fit into the same structural positions in polyatomic ions where phosphorus normally resides.
5. Step 5: Conclude that because arsenic and phosphorus share similar chemical properties and atomic radii, arsenic can substitute for phosphorus in polyatomic ions, maintaining the ion's overall structure and charge.