chemistry

Democratis

490 BCE

Democratis discovered the first accurate assertion of the atom. he said that matter was made up of smaller particles called atomos, meaning invisible.

Empedocles

490 BCE

Known for creating the cosmogenic theory of the 4 classical elements.

Aristotle

338

Belelived the opposite of atomic theory, that all elements were of the 4 classic elements, water, earth, fire, and air.

Evangelista Torricelli

1643

Discover air has weight, therefore atoms have mass.

Antoine Lavoisier

1778

Antoine proposed the law of conservation of mass.

John Dalton

1793

Dalton proposed all matter is made up of tiny prticles, atoms were indecstructable and unchangeable, atoms of the same element are identical, and atoms combine in mew ways in chemical changes.

Joseph Louis Proust

1794

He was best known for his discovery of the law of constant composition in 1794, which said that chemical compounds always combine in constant proportions.

J.J. Thomson

1897

Thomson was responsible for disciveringg the first subatomic particle, the electron. he also created the plum pudding model.

Marie Curie

1898

Researched radioactivity, and in 1898, announced the discovery of 2 new elements, radium and polonium.

Ernst Rutherford

1911

Rutherford proformed the gold foil experiment and discovered the nucleus.

Max Plank

1918

Originated the atomic-quantum theory.

Niels Bohr

1922

Received a nobel prize for the contributions to create the atomic model. Believed that electrons orbited the nucleus much like the planets orbit the sun.

Louis De Broglie

1924

Believed that all atoms had a natural wave effect, helped create the quantum model where electrons orbit the nucleus in a quantum cloud, not like the planets in our solar system.

Erwin Schrodinger

1926

Responsible for creating the first electron cloud model.

James Chadwick

1934

Discovered the neutron, or neutral subatomic partial, fairly large in size. Believed they were in the nucleus with the protons.