-
500 BCE
The Alchemists
All metals are composed of mercury and sulfur and it is possible to change base metals into gold. -
460 BCE
Democritus
Democritus model states matter consists of invisible particles that are atoms and a void that is empty space. He says atoms are unchangeable and indestructible. -
427 BCE
Plato
Plato introduces the atomic theory that ideal geometric forms to serve as atoms according to which atoms broke down mathematically into different triangles. -
340 BCE
Aristotle
Aristotle thought that all materials on Earth were not made of atoms but made of four elements, Earth, Fire, Water, and Air. Aristotle believed all substances were made of small amounts of these four elements of matter. -
Robert Boyle
This states that if the volume of a gas is degreased, the pressure increases proportionally. -
Lavoisier
Lavoisier found that mass is conserved in a chemical reaction. -
John Dalton
In chemical reactions, atoms are combined, separated, or rearranged. -
Dmitri Mendeleev
The Periodic Law states that when elements are arranged according to their atomic number, elements with similar properties will appear at regular intervals. -
J.J. Thomson
Thomson discovered the electron in 1897 and proposed the plum pudding model of the atom in 1904 -
The Curies
They discovered two new elements, radium and polonium. -
Albert Einstein
He mathematically proved the existence of atoms. -
Ernest Rutherford
He was the leader of the exploration of nuclear physics. -
Henry G. J. Mosely
Henry G. J. Mosely reported that the frequencies are proportional to the squares of whole numbers that are equal to the atomic number plus a constant. -
Neils Bohr
Nails Bohr was a Danish physicist who made contributions to understanding atomic structure and the quantum theory. -
Robert Millikan
Roberts study of the elementary electronic charge and the photoelectric effect. -
Werner Heisenburg
That there is a way to formulate quantum mechanics in terms of matrices.
