Year

Event

c. 465 B.C.E.

Democritus first proposes that all matter is made up of small particles. He also first proposes the term “atoms” to describe these particles.

c. 450 B.C.E.

Empedocles proposes the four basic elements: air, fire, earth, and water.

c. 360 B.C.E.

Plato first uses the term “elements” to describe the basic components of matter.

c. 350 B.C.E.

Aristotle expands on the theories of Empedocles to include a fifth basic element: aether.

c. 300 C.E.

Some of the earliest known books on the subject of alchemy are written.

c. 770

Persian alchemist Abu Musa Jabir ibn Hayyan, also commonly known as Geber, develops some of the first experimental methods for isolating chemical compounds.

c. 1000–1650

Alchemists searched for a method to transform cheap metals into gold, an elixir to make people live longer, and a universal solvent. While none of these goals were accomplished, the alchemists did make progress in learning how to use plant extracts and metals to treat illnesses. It’s also worth noting that as early as c. 1000, some chemists were also already beginning to speak out against alchemy, suggesting that some of its goals were impossible to achieve.

c. 1167

The first recorded references to wine distillation were made by Magister Salernus.

c. 1220

An early version of the scientific method was described by Robert Grosseteste.

c. 1250

Fractional distillation was developed.

c. 1260

Arsenic was discovered by Saint Albertus Magnus.

c. 1310

Geber publishes books establishing a theory that all metals are made of sulfur and mercury (which is today known to be incorrect). Several strong acid solutions, still used today, were also described for the first time.

c. 1530

Paracelsus initiates the development of a subfield of chemistry dedicated to extending life, which may be credited as forming the foundations of the study of pharmacy.

1597

An early chemistry textbook, titled Alchemia, is published.

1605

The first description of the scientific method is published by Sir Francis Bacon.

1643

A mercury-based barometer is first invented by Evangelista Torricelli

1661

Robert Boyle publishes a piece of writing titled “The Sceptical Chymist,” explaining the difference between alchemy and chemistry, laying the foundation for the modern field of chemistry.

1662

Boyle’s Law, which relates the pressure and volume occupied by a gas, is first proposed.

1728

The speed of light is determined by James Bradley.

1752

Benjamin Franklin discovers that lightning is electricity.

1754

Carbon dioxide is first isolated.

1772–1777

Oxygen is first isolated independently by both Joseph Priestly and Carl Wilhelm Scheele, and correctly identified by Antoine Lavoisier.

1787

Charles’ Law, which relates the volume and temperature of a gas, is first proposed by Jacques Charles.

1797

The law of definite proportions, which states that elements combine to form compounds in whole number ratios, is proposed by Joseph Proust.

1798

Count Rumford proposes that heat may be a form of energy.

1800

The first chemical battery is created by Alessandro Volta.

1801

Thomas Young performs experiments to demonstrate the wavelike behavior of light by using interference patterns.

1801

Dalton’s Law, describing the relationship between the quantities of components present in a gas mixture and their partial pressures, is introduced by John Dalton.

1805

The fact that water is made of hydrogen and oxygen in a 2-to-1 ratio is first discovered.

1811

Avogadro’s law is proposed. This states that identical amounts of different species occupy the same volume in the gas phase.

1825

The existence of isomers is discovered.

1826

Ohm’s law is introduced, describing the concept of electrical resistance and its relationship to the current through a conductor.

1827

Biomolecules are first classified as carbohydrates, proteins, and lipids (DNA was not yet discovered).

1840

Hess’ law is first proposed, stating that the energy change for a chemical reaction depends only on the identities of the reactants and products, and not on the pathway through which they interconvert.

1843

Heat is demonstrated to be a form of energy.

1848

The concept of an absolute-zero temperature, at which all molecular motion stops, is proposed by Lord Kelvin.

1852

Beer’s Law, which relates the concentration of a sample to its optical absorption at a given wavelength, is introduced by August Beer.

1857

Carbon is proposed to form four bonds with neighboring atoms in molecules.

1859

James Maxwell proposes a description for the velocity distribution of molecules in a gas.

1859–1860

The early foundations of spectroscopy are established by Gustav Kirchhoff and Robert Bunsen.

1864

The law of octaves, an important step leading to development of the modern periodic table, is first proposed.

1865

The number of molecules in one mole of a substance is first determined.

1869

Mendeleev publishes the first version of the modern periodic table, containing 66 elements, and leaving space for yet-to-be-discovered elements.

1869

DNA is first discovered.

1874

The second law of thermodynamics is proposed by Lord Kelvin.

1874

Electric current is proposed to be caused by the motion of electrons.

1876

The concept of free energy is introduced, by Josiah Willard Gibbs to explain chemical equilibria.

1877

Ludwig Boltzmann provides a definition of entropy, along with statistical derivations of several other physical concepts.

1884

Le Chatelier’s principle is first introduced, explaining changes in chemical equilibria upon the introduction of changes in a chemical system.

1887

The photoelectric effect is first discovered.

1888

Radio waves are discovered by Heinrich Hertz.

1893

Alfred Werner establishes that some cobalt complexes involve a central cobalt atom bonded to an octahedral arrangement of six ligands, laying the groundwork for the field of coordination chemistry.

1894

Noble gases are first discovered.

1895

X-ray radiation is discovered.

1897

The electron is discovered.

1900

Planck’s constant is first introduced by Max Planck.

1900

Ernest Rutherford establishes that radioactivity is caused by the decay of atoms.

1901

The Nobel Prizes are awarded for the first time.