Question

How do you find formulas for covalent compounds?

Answer 1

In the above question, it is asked how do we write formulas for covalent compounds. Covalent compounds are formed when two or more nonmetals combine. For this question, we have to look at the nomenclature of covalent compounds. It is mostly similar to naming of ionic compounds.

Complete step by step solution
The nomenclature of binary covalent compounds is similar to naming simple ionic compounds. The first element is listed by its name. The second element is named by taking the stem of their name with the suffix “ide”.
For example:
The name of ${\text{NC}}{{\text{l}}_{\text{3}}}$ is nitrogen trichloride.
Because 3 elements of chlorine are present, tri is added as a prefix. If more than one atom is present, then prefix is used.

Number	Prefix
1	Mono
2	Di
3	tri

If the second element is oxygen, the trailing vowel is usually omitted from the end of a polysyllabic prefix but not a monosyllabic one (that is, we would say “monoxide” rather than “monoxide” and “dioxide” rather than “trioxide”).
When there is a carbon-carbon bond, if a single bond is present then it is referred to as alkane.
If a double bond is present, then it is referred to as alkene.
If a triple bond is present, then it is referred to as alkyne.
We can replace this alk word depending upon the number of carbon atoms present.

Number of carbon atoms	Naming
1	Meth
2	Eth
3	Prop
4	But
5	Pent
6	Hex

For example,
The name of ${\text{C}}{{\text{H}}_4}$ is methane because only single bonds and the number of carbon atoms is 1.

Note
Elements present in the right side of the periodic table are metals whereas the elements present in the right side of the molecule are non-metals. And the elements in the middle of the periodic table are metalloids.
General formula:
Alkane: ${{\text{C}}_{\text{n}}}{{\text{H}}_{{\text{2n + 2}}}}$
Alkene: ${{\text{C}}_{\text{n}}}{{\text{H}}_{{\text{2n}}}}$
Alkyne: ${{\text{C}}_{\text{n}}}{{\text{H}}_{{\text{2n - 2}}}}$