Molecules and Compounds

Molecules and compounds are fundamental concepts in chemistry, and they play an important role in understanding the properties and behavior of matter.

A molecule is the smallest unit of matter that retains the properties of a substance. It is composed of two or more atoms that are chemically bonded together. For example, water is made up of two hydrogen atoms and one oxygen atom, forming the molecule H₂O. The properties of a substance are determined by the type and number of atoms that make up its molecules.

A compound is a substance that is composed of two or more elements that are chemically combined in a fixed ratio. For example, table salt, also known as sodium chloride, is made up of one sodium atom and one chlorine atom, combined in the ratio of 1:1. Unlike elements, compounds cannot be separated into their individual components by physical means, they can only be separated by chemical means.

A molecular formula is the chemical formula of a molecule that shows the exact number of atoms of each element present in the molecule. For example, the molecular formula of water is H₂O, indicating that there are 2 hydrogen atoms and 1 oxygen atom in each molecule of water.

An empirical formula is the simplest whole number ratio of the atoms of each element in a compound. An empirical formula can be determined experimentally by analyzing the percentages of each element in a compound and expressing them as a ratio. For example, the empirical formula of glucose, C₆H₁₂O₆, and it can be simplified as CH₂O.