-
400
Democritus 400 BC
Lived: 460 B.C. to 370 B.C.
Lived in: Abdera, Greece
Published over 70 books
He continuously broke a seashell in half until he could no longer do so.
Determined that all matter consists of atoms. Atoms are indestructable, homogenous, and differ in size, shape, mass, position and arrangement.
Fun fact: He loved to study Geometry as well. -
Period: 400 to
Discoveries
-
John Dalton 1808
Lived: 1766-1844
Where: England
Contributions: Determined that all substances are made of atoms. Atoms are of the same like elements. Elements of different atoms join together to make new substances called compounds.
Fun fact: He was very interested in meteorology. -
J.J. Thomson 1897
Lived: 1856-1940
Where: England
Experiment: Cathorade Experiment
Contributions: Identified electron and negative charge.Determined atoms are spheres with equal numbers of electrons in them.
Fun fact: His father was a bookseller and originally planned for him to be an engineer. -
Ernest Rutherford 1911
Lived: 1871-1937
Where: New Zealand and the United Kingdom
Experiment: Gold Foil Experiment-shot minute particles at a thin sheet of gold and found that some of the particles were deflected
Contributions: Determined that atoms are mostly empty space, contain protons and negative electrons that are outside of the nucleus.
Conclusions: The mass of an atom is concentrated at its center.
Fun fact: He was the 4th of 12 children! -
Niels Bohr 1913
Lived: 1885-1962
Where: Copenhagen, Denmark and the United States
Experiment: Used Rutherford's data to show electrons move around a nucleus according to the amount of energy they have.
Determined: Electrons move in orbits around the nucleus and can jump levels.
Fun fact: Bohr was Jewish and had to leave Denmark once it was occupied by Nazis. -
Erwin Schrodinger 1925
Lived: 1887-1961
Where: Vienna, Austria and Berlin, Germany
Discovered: Atoms have a nucleus of protons and neutrons and that electrons move in space around the nucleus but it cannot be determined where they are at any time.
Fun fact: He studied Italian Painting. -
Werner Heisenberg 1927
Lived: 1901-1976
Where: Germany
Discovered: Atoms have a nucleus of protons and neutrons and that electrons move in space around the nucleus but it cannot be determined where they are at any time.
Fun fact: In 1929 he went on a lecture tour to the US, Japan and India.
