Question

What is the name of the compound that has the formula `PCl_3`?

Answer 1

Phosphorus trichloride

Explanation:

When naming binary covalent compounds (compounds that are composed of 2 different nonmetals), you want to:

• Name the first element. You can obtain the name directly from the periodic table. The symbol, P, tells us that we are dealing with the element phosphorus
• Name the second element by using its root name and change the ending to -ide. The symbol, Cl, tells us that we have the element chlorine. So what you want to do is keep the root name (chlor) and change the -ine ending to -ide.

• Then you add Greek prefixes to indicate the number of atoms that you have of that element:
  

• The subscript that is in front of Cl tells us that we have 3 chlorine atoms, so we place the prefix (tri-) before the name of the second element.

Thus, `PCl_3` is phosphorus trichloride!

I hope this explanation makes sense!