-
400 BCE
Democritus
Democritus's model stated that matter consists of invisible particles called atoms and a void (empty space). -
399 BCE
Plato
He figured out the 5 regular solids, known as the Platonic solids. -
300 BCE
Aristotle
He made pioneering contributions to all fields of philosophy and science, he invented the field of formal logic , and he identified the various scientific disciplines and explored their relationships to each other. -
Robert Boyle
He said that any substance that can be broken into 2 or more substances is not an element -
The Alchemists
They thought all metals are composed of mercury and sulfur and that it is possible to change base metals into gold. -
Lavoisier
Lavoisier is most noted for his discovery of the role oxygen plays in combustion. -
John Dalton
He hypothesized that an atom is a solid sphere that could not be divided into smaller particles. -
Dmitri Mendeleev
Dmitri Mendeleev devised the periodic classification of the chemical elements, in which the elements were arranged in order of increasing atomic weight. -
The Curies
Pierre and Marie Curie discovered the strongly radioactive elements polonium and radium, which occur naturally in uranium minerals. Marie coined the term radioactivity for the spontaneous emission of ionizing, penetrating rays by certain atoms. -
J.J. Thomson
He made this model because it explains the two types of static electricity, he suggested that the atom consisted of positive 'dough' with a lot of negative electrons stuck in it. -
Robert Millikan
He figured out the measurement of the elementary electric charge -
Ernest Rutherford
Ernest Rutherford postulated the nuclear structure of the atom, discovered alpha and beta rays, and proposed the laws of radioactive decay. -
Neils Bohr
He made this to show where the planets are and what they look like from space. -
Henry G.J. Mosley
He experimentally demonstrated that the major properties of an element are determined by the atomic number, not by the atomic weight, and firmly established the relationship between atomic number and the charge of the atomic nucleus. -
Albert Einstein
He discovered that energy and mass are interchangeable -
Werner Heisenberg
The model is a way to help visualize the most probable position of electrons in an atom.
