In nature, it is rare to find one atom on its own. Atoms are usually grouped together in larger structures called molecules. A molecule is the smallest particle of a substance that can exist by itself. The atoms in a molecule are chemically bonded together. They may be atoms of the same element or they may be of different elements. A molecule of carbon dioxide, for example, has two atoms of oxygen and one of carbon.
For millennia, scientists have pondered the mystery of life – namely, what goes into making it? According to most ancient cultures, life and all existence was made up of the basic elements of nature – i.e. Earth, Air, Wind, Water, and Fire. However, in time, many philosophers began to put forth the notion that all things were composed of tiny, indivisible things that could neither be created nor destroyed (i.e. particles).
However, this was a largely philosophical notion, and it was not until the emergence of atomic theory and modern chemistry that scientists began to postulate that particles, when taken in combination, produced the basic building blocks of all things. Molecules, they called them, taken from the Latin “moles” (which means “mass” or “barrier”). But used in the context of modern particle theory, the term refers to small units of mass.
By its classical definition, a molecule is the smallest particle of a substance that retains the chemical and physical properties of that substance. They are composed of two or more atoms, a group of like or different atoms held together by chemical forces.
It may consist of atoms of a single chemical element, as with oxygen (O2), or of different elements, as with water (H2O). As components of matter, molecules are common in organic substances (and therefore biochemistry) and are what allow for life-giving elements, like liquid water and breathable atmospheres.
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