The Atom
- John Dalton – proposed a theory about atoms in 1808.
- William Crookes – investigated what happens when electricity passed through gases.
- J.J Thomson – discovered the electron.
- Robert Millikan – measured the size of the charge on the electron.
- Ernest Rutherford – worked on radioactivity and lead the discovery of the nucleus.
- James Chadwick – discovered the neutron.
Arrangement of electrons in the atom
- Niels Bohr – studied the arrangement of electrons in the atom.
- Werner Heisenberg – put forward his famous Uncertainty Principle.
Erwin Schrödinger – devised mathematical equations to work out the probability of finding an electron in a atom.
The Periodic Table
- Robert Boyle – first chemist to properly define the meaning of the term ‘element‘.
- Humphry Davy – discovered many elements by passing electricity through their compounds.
- Johann Döbereiner – came up with an idea that elements could be categorised in groups of threes called a triad.
- John Newlands – arranged elements in groups of eight and summarised his ideas in his Law of Octaves.
- Dmitri Mendeleev – arranged the elements in order of increasing atomic weight (relative atomic mass). His Periodic Table was quite similar to the modern Periodic Table.
- Henry Moseley – developed a method of determining the atomic number of an element using x-rays.
Radioactivity
- Henri Becquerel – discovered radioactivity.
- Pierre and Marie Curie – discovered polonium and radium.
