History of Chemistry – Key Vocabulary

Vocabulary flashcards summarizing major people, laws, discoveries, and concepts from the lecture’s history of chemistry timeline.

Stoicheia

Aristotle’s name for the four primal roots—water, fire, earth, and air—that compose all matter.

Atomism

Leucippus and Democritus’s idea (440 BC) that matter is made of indivisible particles called atoms.

Plato’s Geometric Elements

Plato’s concept (360 BC) that each element has a special solid: fire-tetrahedron, air-octahedron, water-icosahedron, earth-cube.

Aether

Aristotle’s fifth element— a heavenly substance such as light.

Distillation

Laboratory technique used by ar-Razi (900 AD) to obtain mineral acids from sal ammoniac and vitriols.

Muhammad ibn Zakariya ar-Razi

Medieval Persian chemist who first prepared mineral acids (HCl, H₂SO₄, HNO₃).

St. Albertus Magnus

13th-century scholar who discovered arsenic, silver nitrate, and described making sulfuric acid.

Paracelsus

Renaissance physician who founded iatrochemistry—using chemical methods to treat disease—and first used the word ‘chemistry’.

Iatrochemistry

Paracelsus’s medicinal chemistry that laid foundations of modern pharmaceuticals.

Robert Boyle

Author of The Sceptical Chymist (1661); separated chemistry from alchemy and formulated Boyle’s Law.

Boyle’s Law

Gas law stating pressure of a gas is inversely proportional to its volume at constant temperature.

Joseph Black

Chemist who isolated CO₂ (‘fixed air’) and founded thermochemistry (1750s).

Cacodyl Oxide

Arsenic-based compound Cadet (1757) called the first synthetic organometallic compound.

Henry Cavendish

Discovered hydrogen (‘inflammable air’) in 1766.

Carl Wilhelm Scheele

Isolated oxygen (‘fire air’) in 1774 and many other substances.

Joseph Priestley

Independently isolated oxygen, naming it ‘dephlogisticated air’ (1774).

Antoine-Laurent de Lavoisier

Father of modern chemistry; named oxygen, wrote first modern nomenclature and defined Law of Conservation of Mass.

Jacques Charles

Proposed Charles’s Law relating gas volume and temperature (1787).

Charles’s Law

At constant pressure, gas volume is directly proportional to absolute temperature.

Joseph Proust

Formulated Law of Definite Proportion (1797).

Law of Definite Proportion

Elements combine in fixed, whole-number ratios to form compounds.

John Dalton

Developed modern atomic theory, Law of Multiple Proportions, and Dalton’s Law of Partial Pressures (1803).

Solid Sphere Model

Dalton’s depiction of atoms as indivisible, solid balls.

Dalton’s Law of Partial Pressures

Total pressure of a gas mixture equals the sum of the partial pressures of each component.

Joseph Louis Gay-Lussac

Showed water is 2 H : 1 O and studied gas properties (1805).

Jöns Jakob Berzelius

Introduced modern chemical symbols and relative atomic weight scale (1808).

Amedeo Avogadro

Stated equal gas volumes at same T and P contain equal numbers of molecules (1811).

Avogadro’s Law

Equal volumes of gases, at same temperature and pressure, have equal numbers of molecules.

Lord Kelvin

Defined absolute zero—the temperature where molecular motion ceases (1838).

Friedrich Kekulé

Proposed carbon is tetravalent (1857) and later benzene ring structure.

Spectroscopy

Analytical method founded by Kirchhoff & Bunsen (1859) leading to discovery of new elements.

Stanislao Cannizzaro

Used Avogadro’s ideas to establish atomic weights, enabling development of the periodic law (1860).

Telluric Helix

De Chancourtois’s 3-D periodic arrangement of elements (1862).

Law of Octaves

Newlands’s observation that every 8th element shows similar properties (1864).

Lothar Meyer

Created early periodic table ordered by valence (1864).

Law of Mass Action

Guldberg & Waage’s principle that reaction rate is proportional to the product of reactant concentrations (1864).

Johann Josef Loschmidt

Calculated number of molecules in a mole—later called Avogadro’s number (1865).

Dmitri Mendeleev

Published first modern periodic table (1869) predicting properties of unknown elements.

Svante Arrhenius

Formulated ion theory explaining electrolyte conductivity (1883).

Le Chatelier’s Principle

States how a system at equilibrium responds to external stress (1884).

Eugene Goldstein

Discovered the proton using canal rays (1885).

Henri Becquerel

Discovered radioactivity in uranium salts (1896).

William Ramsay

Identified the noble gases (1894).

J. J. Thomson

Discovered electrons and proposed the Plum Pudding atomic model (1897).

Plum Pudding Model

Thomson’s model of atoms as electrons embedded in a positive ‘pudding’.

Marie & Pierre Curie

Isolated radium and polonium; advanced study of radioactivity (1898).

Ernest Rutherford

Identified alpha, beta, gamma radiation; gold-foil experiment led to nuclear model of atom (1900-1911).

Haber Process

Haber and Bosch’s industrial synthesis of ammonia from N₂ and H₂ (1905).

pH Scale

Sorensen’s logarithmic measure of acidity/basicity (1909).

Molecular Dipole

Debye’s concept describing uneven charge distribution within a molecule (1912).

Bohr Model

Planetary atomic model with electrons in quantized orbits (1913).

Henry Moseley

Introduced atomic number, correcting periodic table order (1913).

Gilbert N. Lewis

Developed valence bond theory and electron-pair acid–base theory (1916/1923).

Schrödinger Equation

Wave equation forming basis of quantum mechanical atomic model (1926).

James Chadwick

Discovered the neutron (1932).

Electronegativity Scale

Quantified by Pauling and Mulliken to express an atom’s tendency to attract electrons (1930s).

Technetium

First synthetically produced element (Perrier & Segre, 1937).

Promethium

Last naturally absent rare-earth element, first synthesized in 1945.

Xenon Hexafluoroplatinate

First compound of a noble gas, synthesized by Neil Bartlett (1962).

Fullerenes

Spherical carbon molecules (C₆₀ etc.) discovered by Kroto, Curl, and Smalley in 1985.

Carbon Nanotubes

Cylindrical fullerenes discovered by Sumio Iijima (1991), crucial to nanotechnology.