Question

What is the formula of phosphorus trichloride?

Answer 1

There are few steps while writing the formula of covalent compounds. We know that the covalent compounds are those compounds which have two nonmetals. We have to know that covalent compounds are otherwise called molecular compounds. These covalent compounds are bonded to one other by covalent bonds.

Complete step by step answer:
We know that the covalent compounds are compounds that contain two nonmetals. We have to write the name of covalent compound by following steps given below,
- Step 1: We have to write the name of the first nonmetal by the name of the element and for the second element, we have to use the suffix “-ide”.
- Step 2: We have to add the prefixes to show the number of atoms presents in each element. For example: If we have two atoms of oxygen present in $N{O_2}$, then we can write the name of the compound as nitrogen dioxide.
We can write the formula of the covalent compound by the two steps given below,
- Step 1: We have to write the symbols of the elements in order given.
- Step 2: We have to write the subscripts with the prefixes.
The compound's name is phosphorus trichloride.
We know that the chemical symbol of phosphorus is P.
We know that the chemical symbol of chlorine is Cl.
We should add the suffix “–ide” to chlorine, so the name becomes chloride. The prefix “tri”- in trichloride indicates the presence of three atoms of chlorine.
So, we can write the formula of phosphorus trichloride is $PC{l_3}$.

Note: We have to remember that while writing formula of the compound, we can omit the prefix “mono-“ when there is only one atom found in the first element but we have include the prefix “mono-“ when there is only one atom found in the second element. In covalent compounds, the sharing of electrons makes the compound electrically neutral.