History of the Atom

Democritus

465

In about 465 BC Democritus made the first atomic model. This is importaint because it started the study of atmoic models, and there were many more advanced models to follow.

John Dalton

Sep 29, 1803

John Dalton published the first atomic thoery. This was an important event becuase it was the very first atomic theory to be published.

Thomson

Sep 30, 1897

Tomson discovered that atoms contain negatively charged particles called electrons. This is important becuase he made an important discovery that helped other scientists in the future.

Curie

Sep 30, 1898

Curie and her husband worked together and discovered two high radioactive elements, she named them radium and polunium. This is important becuase these elements would have gone unknown if they would not have discovered them. The picture is of the element polonium.

Rutherford

Sep 30, 1911

Rutherford created the model of the atom with the nucleus in the center, later they found that the nucleus was made up of one or more positevly charged particles, Rutherford called the particles in an atom's nucleaus protons. This is important because his discorverys led to more discoveries to come.

Bohr

Sep 30, 1913

Bohr was one of Rutherford's students. He revised the atoic model again. He said that electrons are found i only specific orbits around the nucleus. This is important because it led to more discoveries and it was an advancement in the study of the nucleus.

Chadwick

Sep 30, 2015

Chadwick discovered that the particles in the nucleus of an atom became known as the neutron becuase they had no electric charge. This is important becuase it made it possible to create elements heavier than uranium.