History Of The Atom

Democritus

440

• Democritus lived from 460BC to 370BC• He was a Ancient Greek Philosopher• He thought atoms were built like microscopic solar systems• Democritus showed that atoms were indivisible

Antoine Lavoisier

Apr 18, 1778

• Antoine lived from 1743 to 1794• He defined the ‘elements’• He was a French scientist• He also introduced the metric system

John Dalton

Apr 18, 1803

• He is highly praised for his work in chemistry on his atomic theory• He claimed that atoms that contain different elements can vary in mass and size• He worked in chemistry • He was born in 1766

Henri Becquerel

Apr 18, 1896

• Becquerel discovered radioactivity• He was awarded the Nobel prize in physics shared with Marie Pierre Curie• He recognised that some radiation released by uranium was deflected by a magnet• He was born in 1852

J.J. Thomson

Apr 18, 1897

• Thomson was born in 1856• He began the theory of electromagnetism• He proved that there were smaller particles inside the atom by discovering the electron

Niels Bohr

Apr 18, 1922

• He realised that to keep finding more about the atom they needed to study the nucleus• He and August Krogh, a Danish physiologist applied to build a cyclotron (a particle accelerator)• He used the cyclotron to produce isotopes of elements involved in organic processes• He was born in 1885

Louis De Brogli

Apr 18, 1924

• He was born in 1900• He was from Austria• He won the Nobel prize in 1945 for physics• He discovered that in one atom no 2 electrons can occupy the same quantum state at the same time• He was from France• He introduced the particle-wave duality• He won the noble prize for physics in 1929• His theory helped clarify how atoms, molecules and protons act

Werner Heisenberg

Apr 18, 1925

• He was born in 1901• He was from Germany• His theory of quantum theory mechanics provided a matrix way to clarify stationary discrete energy states• He won the Nobel prize for physics in 1932

Erwin Schrödinger

Apr 18, 1926

• Schrödinger was from Austria• He introduced the Schrödinger wave which is a mathematical equation of wave mechanics • His Schrödinger wave earned him the Nobel prize for physics in 1933• The Schrödinger wave is the most widely used piece of mathematics in modern quantum theory• He was born in 1887

Max Born

Apr 18, 1928

• He was born in 1882• He is best known for his analysis of how subatomic particles behave• His studies led to the reassessment of the original quantum theory• He won the Nobel prize for science in 1954

Paul Dirac

Apr 18, 1930

• He was born in 1902 • He was from England• He made underlying contributions to the expansion of quantum mechanics• The Dirac equation explains the behaviour of fermions like the electron

James Chadwick

Apr 18, 1932

• He was born in 1891• He was from England• Chadwick discovered the neutron • He studied at Cambridge with Ernest Rutherford where they studied the transmutation of elements by attacking them with alpha particles

Carl Anderson

Apr 18, 1932

• He was an American physicist • He was born in 1905• When he was analysing cloud-chamber pictures of cosmic rays he found a number of track whose composition looked like they were caused by positively charged particles but too small to be protons

Wolfagang Pauli

Apr 18, 1940

• He was born in 1900• He was from Austria• He won the Nobel prize in 1945 for physics• He discovered that in one atom no 2 electrons can occupy the same quantum state at the same time

Hideki Yukawa

Apr 18, 1955

• Yukawa was born in 1907• He was from Japan• Yukawa said that a strong short-range force between either neutrons or protons overcame electrical repulsion between protons in the nucleus without affecting the electrons in the atom