Nuclear History
A timeline of the most significant discoveries and moments in the history of nuclear physics and radiochemistry.
400 BC
Democritus
Atomic Theory
Proposed that all matter is composed of small, indivisible particles called 'atomos'.
IMPACT: Laid the philosophical foundation for the particle nature of matter.
1803
John Dalton
Modern Atomic Theory
Formulated the first modern scientific description of the atom as the fundamental building block of chemical elements.
IMPACT: Established stoichiometry and the law of multiple proportions.
1895
Wilhelm Röntgen
Discovery of X-Rays
Discovered X-rays while experimenting with cathode rays, identifying unknown radiation that could pass through solid objects.
IMPACT: Revolutionized medical diagnostics and non-destructive testing.
1896
Henri Becquerel
Radioactivity
Accidentally discovered that uranium salts emit radiation without external stimulation.
IMPACT: Revealed that atoms are not immutable and contain internal energy.
1897
J.J. Thomson
The Electron
Identified the electron using cathode ray tubes, proving atoms are divisible.
IMPACT: Led to the 'Plum Pudding' model and the field of subatomic physics.
1898
Marie & Pierre Curie
Polonium & Radium
Isolated two new radioactive elements from pitchblende, coining the term 'radioactivity'.
IMPACT: Demonstrated the immense energy potential within atomic nuclei.
1905
Albert Einstein
Mass-Energy Equivalence
Formulated E=mc², relating mass and energy, and explained the photoelectric effect.
IMPACT: Provided the theoretical basis for nuclear energy.
1911
Ernest Rutherford
The Nucleus
Discovered the dense, positively charged nucleus via the gold foil experiment.
IMPACT: Overturned the plum pudding model; established the nuclear model of the atom.
1913
Niels Bohr
Bohr Model
Proposed that electrons orbit the nucleus in quantized energy levels.
IMPACT: Explained atomic emission spectra and stable electron orbits.
1932
James Chadwick
The Neutron
Discovered the neutron, a neutral particle in the nucleus.
IMPACT: Explained isotopes and provided the ideal projectile for nuclear fission.
1934
Irene & Frederic Joliot-Curie
Artificial Radioactivity
Synthesized new radioactive isotopes by bombarding stable elements with alpha particles.
IMPACT: Allowed for the creation of designer isotopes for medicine and industry.
1938
Hahn, Strassmann & Meitner
Nuclear Fission
Discovered that uranium nuclei could split when bombarded with neutrons, releasing massive energy.
IMPACT: Unlocked the potential for nuclear power and weapons.
1942
Enrico Fermi
First Critical Pile (CP-1)
Achieved the first self-sustaining controlled nuclear chain reaction in Chicago.
IMPACT: Marked the beginning of the nuclear age.
1951
EBR-I Team
Electricity from Nuclear
The Experimental Breeder Reactor I (Idaho) lit four light bulbs with nuclear energy.
IMPACT: Proved the viability of nuclear power generation.
1964
Gell-Mann & Zweig
Quark Model
Proposed that protons and neutrons are composed of smaller fundamental particles called quarks.
IMPACT: Foundational to the Standard Model of particle physics.