Atomic Structure Timeline

Democritus develops theory that everything is made of atoms

Aristole believes in 4 elements instead of atoms; adds a fifth, aether.

Berzelius complied list of atomic weights

Avogadro develops hypothesis later named after him about gasses and their proportionality

Dalton introduces atomic theory

Mendeleev creates periodic table of elements

Thomson showed how different volumes of gasses react in different ways in his book Elements of Chemistry

Becquerel is the first person to discover evidence of radioactivity

Curie discovers two new radioactive elements; coins term "radioactivity"

Lavoisier develops oxygen theory of combustion

Rutherford develops his model of an atom, with a nucleus full of mass with low-mass electrons surrounding it

Moseley performs experiment and finds atomic number closely correspond to the nucleus's electrical charge atomic number

Chadwick discovers neutron

Milikan measures the elementary electric charge

Bohr discovers that electrons in the valence layer can transfer between atoms

Plank develops theory of quantum physics/energy quanta

Schrödinger helps develop the theory of quantum mechanics with his equation

Heisenberg gets Nobel Prize for "the creation of quantom mechanics"; matrix formulation

Meitner leads team of scientists to discover nuclear fission of uranium