Timeline of atomic and subatomic physics

A timeline of atomic and subatomic physics. In 6th century BCE, Acharya Kanada proposed that all matter must consist of indivisible particles and called them "anu". He proposes examples like ripening of fruit as the change in the number and types of atoms to create newer units. 430 BCE Democritus speculates about fundamental indivisible particles—calls them "atoms" 1766 Henry Cavendish discovers and studies hydrogen 1778 Carl Scheele and Antoine Lavoisier discover that air is composed mostly of nitrogen and oxygen 1781 Joseph Priestley creates water by igniting hydrogen and oxygen 1800 William Nicholson and Anthony Carlisle use electrolysis to separate water into hydrogen and oxygen 1803 John Dalton introduces atomic ideas into chemistry and states that matter is composed of atoms of different weights 1805 (approximate time) Thomas Young conducts the double-slit experiment with light 1811 Amedeo Avogadro claims that equal volumes of gases should contain equal numbers of molecules 1832 Michael Faraday states his laws of electrolysis 1871 Dmitri Mendeleyev systematically examines the periodic table and predicts the existence of gallium, scandium, and germanium 1873 Johannes van der Waals introduces the idea of weak attractive forces between molecules 1885 Johann Balmer finds a mathematical expression for observed hydrogen line wavelengths 1887 Heinrich Hertz discovers the photoelectric effect 1894 Lord Rayleigh and William Ramsay discover argon by spectroscopically analyzing the gas left over after nitrogen and oxygen are removed from air 1895 William Ramsay discovers terrestrial helium by spectroscopically analyzing gas produced by decaying uranium 1896 Antoine Becquerel discovers the radioactivity of uranium 1896 Pieter Zeeman studies the splitting of sodium D lines when sodium is held in a flame between strong magnetic poles 1897 Emil Wiechert, Walter Kaufmann and J.J.