Final answer:
The molecular compound Ca3(PO4)2 is named calcium phosphate. The naming starts with the metal, followed by the name of the polyatomic ion, without using numerical prefixes for the metal in ionic compounds.
Step-by-step explanation:
To name the molecular compound Ca3(PO4)2, we consider both the cations (positively charged ions) and anions (negatively charged ions) in the compound. Since this compound contains polyatomic ions, we need to recognize those ions and use their common names. The calcium ion is simply named calcium, and the polyatomic ion (PO4) with a charge of 3- is known as phosphate.
Therefore, instead of beginning with 'Tricalcium' as you may initially think, you begin with the name of the metal as it appears on the periodic table, which, in this case, is Calcium. Then, since (PO4)2 is the phosphate group and there are two of these groups in the compound, the compound name is calcium phosphate. This naming convention keeps it clear and systematic for any compound containing polyatomic ions. The numerical prefixes such as 'mono-', 'di-', 'tri-', etc., are typically not used for the metal in ionic compounds but are commonly used for naming covalent compounds to indicate the number of atoms present.
For example, the compound CCl4 is named carbon tetrachloride, indicating there is one carbon atom and four chlorine atoms in the molecule.