Download The History of the Atom Carousel Who-What-When

The History of the Atom Carousel
Who-What-When
1. Aristotle and Democritus
These contemporary Greek philosophers, c.425BC, had
conflicting theories of matter. Aristotle believed in the
then current thought that there were four elements:
earth, air, fire, and water. To this he added ‘Aether’
meaning outer space and the planets. Democritus
believed matter was composed of many tiny pieces and
the smallest were indivisible. He called these pieces
‘atomos’ which is Greek for indivisible.
2. Joseph Priestly and Antoine Lavoisier
Among Joseph Priestly contributions were the study of
‘airs’ or gasses. In one of his experiments he isolated and
‘discovered’ a new gas – oxygen, in 1772. He visited
Antoine Lavoisier in France and explained what he had
done. Lavoisier was a noted scientist who used better
methodology and measurements in his work. For
Priestly’s ‘air’ he ‘invented’ the term oxygen as the
emitted gas. Lavoisier published the first text on
Chemistry, giving the first names to many of the elements
on the periodic table.
3. John Dalton
1802, The Atomic Theory of matter; each type of matter is 1
type of atom – each atom an element is identical – atoms are
indivisible and cannot be created or destroyed
4. J. J. Thomson/Ernest Rutherford/James Chadwick
Discover’s of the electron (1897), the proton (1909), and
the Neutron (1932). 35 years of teacher-student
connected study. Rutherford proposed the 1st atomic
model; plum pudding/cookie dough
5. Niels Bohr and Gilbert Lewis
1913 - Neils Bohr. Proposes an atomic model where the
electrons are arranged in multiple energy layers or electron
shells. The shells nearer the nucleus have lower energy and
fewer electrons.
1916 - Gilbert Lewis. Proposes the term ‘valence’ for the
outer electron shell and determines that atom-atom bonding
occurs here.