Timeline Diagram
322 BC - ARISTOTLE
1897 - THOMPSON
all things are made
up of the four
elements fire, water,
air, and earth.
Thompson thought the atom was a
sphere of positive charge, but
negatively charged electrons were
spread evenly among the positive
charge.
460-370 BC DEMOCRITUS
“The universe is composed
of two elements: the atoms
and the void in which they
exist and move.”
1803 - DALTON
1913 - BOHR
the electrons orbit the
nucleus in a
predetermined route.
1911 - RUTHERFORD
the atom has an atomic nucleus
all things are made up of atoms, and
atoms cannot be split into smaller
containing protons and neutrons.
pieces. He also said that all atoms of the He also stated that the electrons go
same element are exactly alike
around the nucleus in a electron
orbit
1926 HEISENBERG/SCHRO
DINGER
The atomic model created by
Heisenberg and Schrodinger is
known as the quantum
mechanical model of the atom.