-
427 BCE
Plato
Plato theorizes solid from of matter are composed of indivisible elements shaped like triangles he was also born during the classical period of Athens -
250 BCE
Solar System Model
A solar system is a system of stars, planets, moons, and other objects, bound together by gravitational orbit -
122 BCE
The alchemists
the alchemists observed that substances continouisly changed from one form to another. -
5 BCE
Democritus
Democritus believed that atoms were uniformed solid hard and incompressible and indestructible and they moved in infinite numbers through empty speed -
Robert Boyle
Regarded as the first modern chemist. He contributed to the development of atomic theory by demonstrating that matter is made of tiny particles that he called corpuscles, but that are known as atoms today. -
Billiard ball model
defined an atom to be a ball-like structure, as the concepts of atomic nucleus and electrons were unknown at the time. -
Antoine Lavoisier
He deceived that matter was composed of atoms that were not created or destroyed during chemical reactions which is called the law of conservation of mass -
John Dalton
Is one of the most infuential chemists in the world. He introduced thr atomic theory to chemistry. He theorized that atoms would repel each other -
Dmitri Mendeleev
He discovered how to use the periodic table other wise known as periodic law he also lived in the same time period as Marie curie -
Amadeo Avogrado
Created the Avogrado theory which states that equal volumes of gases under the same conditions of temperature and pressure will contain equal numbers of molecules he was also Count of Quaregna and Cerreto was an Italian scientist -
JJ thompson
Discovered the electron and went on to propose a model for the structure of an atom he was a British physicists and Nobel laureate in physics. -
Pierre and Marie Curie
Discovered the strongly radioactive elements plutonium and Radium where alive during world war 1 -
Plum Pudding Model
the electrons as negatively-charged particles embedded in a sea of positive charge. The structure of Thomson's atom is analogous to plum pudding, an English dessert -
Albert Einstein
Albert Einstein mathematically predicted the size of both atoms and molecules. He proved the existence of atoms by the movement of molecules in a liquid caused by the Brownian motion. also in in 1905 he mathematically proved the existence of the atom, a fundamental step in determining atomic theory. -
Robert Milikan
Milikens worked proved that electrons have a fixed measurable charge that does not vary -
Ernest Ruthford
Discovered that atoms have a small dense positively charged nucleus he is known as the father of nuclear physics -
Henry G.J Mosely
Henry discovered atomic numbers he conducted that it was the postitive charges in the atomic numbers he also contributed to the justification to physical laws -
Neils Bohr
He developed the Bohr model of an atom and he received the Nobel prize in 1922. He was a danish physist who also made foundational contributions to understanding atomic structure -
Electron Cloud model
an electric cloud model is a function describing the location and wave-like behavior of an electron in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom's nucleus -
James Chadwick
He discovered that atoms consisted of protons, electrons and another subatomic particles called neutrons he also wrote the final draft of the Maud report