Naming Covalent Compounds

What are Covalent Compounds?

Covalent compounds are formed when two nonmetal atoms share valence electrons to form a covalent bond. Valence electrons are the atom’s outermost electrons. Elements want to fill their electron orbitals, or shells, with electrons, so they will form bonds with other atoms that will allow them to do so. The word ‘covalent’ is made up of the words ‘co’ (share) and ‘valent’ (valence electrons).

Formation of Covalent Bond

Elements with extremely high ionisation energies are incapable of transferring electrons, while elements with extremely low electron affinity are incapable of absorbing electrons. The atoms of such elements tend to share electrons with atoms of other elements or atoms of the same element in such a way that both atoms achieve octet configuration in their respective valence shells and thus achieve stability. A covalent Bond refers to such an association formed by the sharing of electron pairs among different or similar kinds.

Table of Contents

• Rules for Naming Covalent Compounds
• Prefixes used for Covalent Compounds
• Naming Covalent Compounds With Three Elements
• Solved Examples
• Frequently Asked Questions – FAQs

Rules for Naming Covalent Compounds

A binary compound is made up of only two elements. The names are referred to as systematic names.

The rules for naming binary covalent compounds are as follows:

1. First, identify the element name of the nonmetal that is farthest to the left and farthest to the bottom of the periodic table.
2. Second, use the element name for the other nonmetal, but shorten it and add a -ide ending.
3. To indicate the number of atoms in an element, place prefixes (mono-, di-, tri-, etc.) in front of the element name. In the element formula, the number prefix corresponds to the subscript. If there is no subscript, it means that the element only has one atom, and the prefix is “mono-.” However, in the first element’s name, leave out the “mono-” prefix.

We use common names rather than systematic names for some simple covalent compounds.

Prefixes used for Covalent Compounds

Greek prefixes are used to name compounds based on the elemental subscript, which specifies the number of atoms present in the compound.

Examples-

• PCl₅ – Phosphorus pentachloride
• SO₂ – Sulphur dioxide
• CO₂ – Carbon Dioxide
• N₂O₅ – Dinitrogen pentoxide
• BrF₅ – Bromine pentafluoride

Naming Covalent Compounds With Three Elements

These are the rules for naming covalent compounds with three elements.

• Specify the formula
• Specify the charge
• Specify the formula

For example- Na₂SO₄ is composed of three elements- sodium which is a cation and sulphate. Therefore, it is named sodium sulphate.

Similarly, Li₄HPO₄ is composed of three elements: lithium, a cation, and hydrogen phosphate. As a result, it is named lithium hydrogen phosphate.

Also Read:

• Naming Ionic Compounds
• Common Polyatomic Ions
• Nomenclature of Organic Compounds

Solved Examples

1. Write the names of each compound-

a. CO

b. CF₄

c. CCl₄

Solution.

a. Carbon Monoxide

b. Carbon tetrafluoride

c. Carbon tetrachloride

2. Write the names of each compound-

a. H₂O

b. CH₄

c. NH₃

Solution.

a. Water

b. Methane

c. Ammonia