Pre-scientific ancient Greek philosophers such as Leucippus and Democritus theorized that the cosmos is made up of atoms and voids, which gave rise to the current concept of molecules. Around 450 BC, Empedocles envisaged basic elements like fire, earth, air, and water, as well as forces of attraction and repulsion that allowed the elements to interact.
Heraclitus had previously asserted that fire, or change, was vital to our existence and that it was formed by combining opposing characteristics. The essential building block of the heavenly bodies was thought to be a fifth element, the incorruptible quintessence aether. Aristotle embraced Leucippus' and Empedocles' viewpoints, as well as the aether, and passed them down to medieval and Renaissance Europe.
In the 19th century, scientific data for pure chemical components and how individual atoms of distinct chemical elements, such as hydrogen and oxygen, can unite to form chemically inert molecules, such as molecules of water, began to emerge.
Leucippus, Democritus, and Epicurus provided the first theories on the forms and connectedness of atoms, reasoning that the solidity of the substance matched the shape of the atoms involved.
The concept of aggregates or units of connected atoms may be traced back to Robert Boyle's 1661 hypothesis, published in his classic work The Sceptical Chymist, that matter is made up of clusters of particles and that chemical change is caused by cluster rearrangement. Boyle proposed that matter's fundamental ingredients were various types and sizes of particles known as 'corpuscles,' which could self-organize into groupings.
Based on the corpuscular theory, Nicolas Lemery, a French scientist, stated in 1680 that the acidity of any substance was defined by its pointed particles, whereas alkalis were endowed with pores of variable widths. According to this theory, a molecule is made up of corpuscles connected by a geometric arrangement of points and pores.
Jean Perrin, a French physicist, was awarded the Nobel Prize in Physics in 1926 for convincingly confirming the existence of molecules. He achieved it by employing three separate ways to calculate Avogadro's number, all of which included liquid phase systems.
K.L. Wolf, a chemist, used the term 'supermolecules' to explain hydrogen bonding in acetic acid dimers in 1937. This would lead to the field of supermolecular chemistry in the long run.
Erwin Wilhelm Müller, a physicist, develops the field ion microscope in 1951 and is the first to view atoms, such as bound atomic groupings at the tip of a metal point.