Carla Mooney - Chemistry: Investigate the Matter that Makes Up Your World

460 BCE370 BCE

Democritus of ancient Greece introduces the idea of matter in the form of particles, which he calls atoms. He proposes that all matter is made up of these tiny units.

300 BCE

Aristotle of ancient Greece declares that there are only four elements: fire, air, water, and earth. He believes that all matter is made from these four elements.

300 BCE

For many centuries, early chemists called alchemists unsuccessfully attempt to change lead and other metals into gold. They are also unsuccessful in attempts to create an elixir of life that would cure all illnesses and enable people to live longer.

1662

Sir Robert Boyle develops fundamental gas laws and defines the inverse relationship between pressure and any gas, which would become known as Boyles law.

1702

Georg Stahl names phlogiston, the substance he believes is released during the process of burning.

1754

Joseph Black identifies carbon dioxide gas, which he calls fixed air.

1774

Joseph Priestley discovers oxygen, carbon monoxide, and nitrous oxide.

1787

Antoine Laurent Lavoisier publishes his system for classifying and naming chemical substances. He is later known as the father of chemistry.

1803

John Dalton develops a theory that matter is made of atoms of different weights and is combined in ratios by weight. He also proposes that atoms are spherical and are in motion.

1809

Joseph Louis Gay-Lussac shows that when gases combine, they do so in simple ratios by volume, which is later known as his law of combining volumes.

1828

Friedrich Whler synthesizes urea, proving that organic compounds can be produced from inorganic materials.

1865

Johann Josef Loschmidt determines the exact number of molecules in a mole, later called Avogadros number.

1869

Dmitri Mendeleev publishes the first modern periodic table to classify elements. The table allows scientists to predict the properties of undiscovered elements.

1884

Henry Louis Le Chatelier develops Le Chateliers principle to explain how chemical equilibrium responds to external stresses.

1898

J.J. Thomson discovers the electron.

1898

Marie Curie and her husband, Pierre, isolate the element radium. Because they do not know about the danger of radioactivity, they work without any protection.

1900

Ernest Rutherford discovers that decaying atoms create radioactivity.

1906

Frederick Soddy observes chemically identical elements with different atomic weights and names them isotopes.

1908

Robert Millikan measures the charge of a single electron.

1909

S.P.L. Sorensen invents the idea of pH and develops methods for measuring acidity.

1911

Ernest Rutherford, Hans Geiger, and Ernest Marsden prove the nuclear model of the atom, which has a small, dense, positively charged nucleus surrounded by an electron cloud.

1913

Niels Bohr proposes the Bohr atomic model. His model shows electrons traveling in orbits around an atoms nucleus. Bohr proposes that an atoms chemical properties are determined by how many electrons are in its outer orbits.

1932

James Chadwick discovers the neutron.

1936

Scientists confirm the creation of the first synthetic element, technetium.

1938

Otto Hahn discovers the process of nuclear fission.

1938

Linus Pauling publishes his work on chemical bonds.

1949

Willard Libby develops radiocarbon dating.

1965

Robert Woodward wins the Nobel Prize for his syntheses of compounds such as cholesterol, quinine, chlorophyll, and cobalamin.

2014

Scientists report that acid rain has changed the water chemistry of many of Canadas lakes, which has led to an increase in a tiny plankton coated in gel. Increased numbers of these tiny organisms make the lakes appear as if they have transformed into jelly.

2015

Chemists successfully use synthetic nanoparticles to deliver therapies to the livers of patients with liver cancer. The therapies suppress their tumors.