-
460
Democritus
• He was a pupil of Leucippus
• He was born in Abdera, Trace in Greece
• His theory was that if you kept cutting a piece of silver
in half you would end up with an atom
• He came up with the name atom
born 460 B.C -
Dalton
• Meteorologist, chemist, and physicists
• Quaker background
• His atomic theory:
1) All substances are made up of atoms, atoms are small particles that cannot be divided, created, or destroyed
2) Atoms of the same element are exactly alike and atoms of different elements are different
3) Atoms join with other atoms to make new substances -
Thomson
• British
• Full name Joseph John Thomson
• Discovered the electron
• He estimated the value of the electrons charge -
Rutherford
• Zealand born
• Known as father of nuclear physics
• Nobel prize in chemistry
• His theory was labelling the atom as having a central positive nucleus surrounded by negative orbiting electrons -
Bohr
• Danish physicist
• Nobel prize winner in physics
• His father was a physiology professor
• He added onto Rutheford’s theory by saying that by assuming that electrons travel in stationary orbits defined by their angular momentum -
The Modern Atomic Theory
Matter is composed of discrete units called atoms, as opposed to the antiquated concept which held that matter could be divided into any arbitrarily small quantity.
