Question

Write the names for the following compounds PCl5

Answer 1

Phosphorus pentachloride.

Step-by-step explanation

There are two elements in PCl₅:

• P- Phosphorus;
• Cl- Chlorine.

Both P and Cl are nonmetals. Nonmetals tend to share electrons to form covalent molecules. PCl₅ is likely to be a covalent molecule. The name of PCl₅ and other molecules of two elements comes in a couple of parts:

• First prefix- How many atoms of the first element (P in this case) in the molecule? Di- for two, tri- for three, etc. There's no mono- here. Omit the first prefix if there's only one atom of the first element in the molecule (as in this case.)
• Name of the first element. Phosphorus.

• A space in between.

• Second prefix- How many atoms of the second element (Cl in this case) in the molecule? Similar to the first prefix, however include "mono-" if there's only one atom of the second element in the molecule. There are five Cl atoms in each molecule. Hence the prefix "penta-."
• Name of the second element as if it was an anion. The anion from Cl is the chloride ion Cl⁻. Hence the name "chloride."

Combining the parts:

`\underbrace{\text{phosphorus}}_{\text{Na}\text{me of first element}}\; \underbrace{\text{penta}}_\text{prefix}\underbrace{\text{chloride}}_\text{like an ion}`.

Hence the name: phosphorus pentachloride.