Naming Ionic and Molecular Compounds

Molecular Compounds

Naming Molecular Compounds

Molecular compounds are composed of two or more nonmetal elements. The naming of these compounds follows specific rules to indicate the number and type of atoms present in the molecule.

• First Element: The name of the first element is written in full. The element that appears first in the formula is named first.

• Second Element: The second element is named as if it were an anion (root of the element name + "-ide").

• Prefixes: Prefixes are used to indicate the number of atoms of each element present in the compound. The prefix 'mono-' is usually omitted for the first element.

Common Prefixes Used in Naming

Number	Prefix
1	mono-
2	di-
3	tri-
4	tetra-
5	penta-
6	hexa-
7	hepta-
8	octa-
9	nona-
10	deca-

Example: Naming N2O

• Step 1: Identify the elements: Nitrogen (N) and Oxygen (O).

• Step 2: There are two nitrogen atoms and one oxygen atom.

• Step 3: Use the prefix 'di-' for two nitrogens: dinitrogen.

• Step 4: Use the prefix 'mono-' for one oxygen, but 'mono-' is often omitted for the second element: monoxide.

• Final Name: Dinitrogen monoxide.

Additional info: The systematic naming of molecular compounds helps avoid confusion and ensures that each compound has a unique, descriptive name. For example, N2O is called dinitrogen monoxide, while NO2 is nitrogen dioxide.