The race for the atom
14 steps · 1808 – 2012
In little more than a century the atom went from hypothesis to being split in two. From the relative weight of the elements to the Higgs boson, by way of the bomb and nuclear power.
▶ Play on the globe- 11803-1808 · Manchester, England · Theorem, law or theory
Dalton's atomic theory and law of multiple proportions
Dalton revives an old Greek idea with data: each element is made of identical atoms with their own weight, combining in fixed proportions.
🌍 View on the globe - 21869 · Saint Petersburg, Russia · Theorem, law or theory
Periodic law and periodic table
Mendeleev orders the elements by weight and finds their properties repeat. He leaves gaps for elements not yet known… and is proved right.
🌍 View on the globe - 31896 · National Museum of Natural History, Paris, France · Discovery
Natural radioactivity
Uranium salts fog a photographic plate kept in a drawer. The atom gives off energy on its own: it is not indivisible.
🌍 View on the globe - 41897 · Cavendish Laboratory, Cambridge, England, United Kingdom · Discovery
The electron
Thomson finds a particle a thousand times lighter inside the atom: the electron. The atom has parts.
🌍 View on the globe - 51898 · School of Industrial Physics and Chemistry, Paris, France · Discovery
Polonium and radium; radioactivity as an atomic property
Marie and Pierre Curie isolate two new elements from tonnes of pitchblende. Radium glows in the dark and turns radioactivity into a field of study.
🌍 View on the globe - 61911 · University of Manchester, England, United Kingdom · Discovery
The atomic nucleus
Some alpha particles bounce back off gold foil «like a shell off tissue paper». Almost all the atom's mass sits in a tiny nucleus.
🌍 View on the globe - 71913 · Copenhagen, Denmark / Manchester, United Kingdom · Discovery
Bohr model of the atom
Bohr puts electrons in allowed orbits and explains the colours hydrogen emits. Quantum physics enters the atom.
🌍 View on the globe - 81932 · Cavendish Laboratory, Cambridge, England, United Kingdom · Discovery
The neutron
Chadwick finds the missing piece of the nucleus: a particle with no charge. The neutron will be the key to breaking it.
🌍 View on the globe - 91938 · Kaiser Wilhelm Institute for Chemistry, Berlin-Dahlem, Germany · Discovery
Nuclear fission
Hahn and Strassmann bombard uranium with neutrons and get barium; Meitner and Frisch understand it: the nucleus has split, releasing enormous energy.
🌍 View on the globe - 101942 · Chicago, Illinois, United States (Stagg Field, University of Chicago) · Invention or technique
Nuclear reactor (Chicago Pile-1)
Under the stands of a Chicago stadium, Fermi's team achieves the first controlled chain reaction. Fission can be switched on and off.
🌍 View on the globe - 111945 · Los Alamos, New Mexico, United States (Trinity test at Alamogordo, 16-7-1945) · Invention or technique
Atomic bomb
The Manhattan Project turns the chain reaction into a weapon. Hiroshima and Nagasaki change warfare and twentieth-century politics.
🌍 View on the globe - 121954-1957 · Obninsk, USSR (1954); Calder Hall, United Kingdom (1956); Shippingport, Pennsylvania, United States (1957) · Invention or technique
Civil nuclear power plant
In Obninsk, near Moscow, a reactor feeds electricity to the grid for the first time: the atom in civilian service.
🌍 View on the globe - 131958-1968 · Kurchatov Institute, Moscow, USSR · Invention or technique
Tokamak magnetic confinement fusion
The Soviets confine a plasma at millions of degrees with doughnut-shaped magnetic fields. It is the path to imitating the Sun: fusing nuclei instead of splitting them.
🌍 View on the globe - 142012 · CERN, Geneva, Switzerland (LHC, ATLAS and CMS experiments) · Discovery
The Higgs boson
CERN's LHC detects the particle that explains why the others have mass. It crowns the Standard Model, the recipe for everything made of atoms.
🌍 View on the globe