Atoms Timeline

By Sonia Munro

Main

Greek Philosepher, Damocritus

460 B.c.e - 370 bce

Democritus explains that matter is made up of particles with the ideal qualities they are all to small to see, unable to be divided, they are solid, eternal because they are perfect, they are surrounded by empty space and have an infinite number of shapes

English chemist, John Dalton

1766 - 1844

During the 19th century, a huge amount of data on how substances react with each other was collected and studied. From this data, some simple laws of chemical reactoins had been devised.

Dimitri Mendeleïev

1869

This Russian scientist develops a table which classifies all the chemical elements known at that time according to their
chemical properties. This table later served to methodically classify all of the atoms, both natural and man made, by their atomic number.

Thompson

1904

In 1904, he proposed an initial model of an atom,since nicknamed "Thompsons pudding". He imagined the atom as a sphere full of an electrically positive substance mixed with negative electron "like the raisins in a cake".

Niels Bohr

1911

he creates a new version of the atom where orbits of the electrons can't be just anywhere but are "quantified"; only certain particular orbits are permitted for the electron. It's not until one jumps from one orbit to another that it can produce light

Ernest Rutherford

1913

Rutherford discovered the atomic nucleus.His new model of the atom showed that its positive electric charge and the majority of its its mass were concentrated in an almost
point sized nucleus.

Chadwick

1932

He discovers the neutrally charged neutron to further prove Rutherford's studies.

Modern Atom

2013

This describes the atom as a mostly empty space with a tiny nucleus in the centre which has an equal balance of electrons and neutrons.