How many atoms of calcium, phosphorus, and oxygen are present in one formula unit of Ca3(PO4)2?

• A. 3 calcium, 4 phosphorus, 8 oxygen
• B. 3 calcium, 2 phosphorus, 8 oxygen
• C. 3 calcium, 2 phosphorus, 6 oxygen
• D. 3 calcium, 2 phosphorus, 8 oxygen

Answer: (D)

Verified step by step guidance

1. Identify the chemical formula given: Ca3(PO4)2. This represents one formula unit of the compound.
2. Determine the number of calcium (Ca) atoms directly from the formula. The subscript 3 outside Ca indicates there are 3 calcium atoms.
3. Look inside the parentheses (PO4) and note the subscript 2 outside the parentheses. This means the entire PO4 group is present twice.
4. Count the atoms inside the PO4 group: 1 phosphorus (P) atom and 4 oxygen (O) atoms. Since there are 2 such groups, multiply each by 2.
5. Calculate the total atoms: Phosphorus atoms = 1 × 2 = 2, Oxygen atoms = 4 × 2 = 8. So, the formula unit contains 3 calcium, 2 phosphorus, and 8 oxygen atoms.