The History of the Atom

Democritus

459 BCE

Discoveries and contributions made by Democritus
- Democritus discovered the idea of the atom. This discovery is very Important because if it weren't for the discovery of the atom atomic theory would still consist of many questions.

Democritus

450 BCE

This is Democritus' atomic theory:
1.All matter consists of invisible particles called atoms.
2. Atoms are indestructible.
3. Atoms are solid but invisible.
4. Atoms are homogenous.
5. Atoms differ in size, shape, mass, position, and arrangement.
->Solids are made of small, pointy atoms.
->Liquids are made of large, round atoms.
->Oils are made of very fine, small atoms that can easily slip past each other. Read more @

Democritus

450 BCE

Experiments
- An Experiment that was carried out by Democritus that was very simple and can be easily recreated today. Democritus took a see shell and broke it in half, and continued to break it down until it was in small particles powder. When he obtained powder particle he could no longer break them down any farther proving the atomic theory of not being able to break down atoms. (There was no date provided for this information)

Dalton

Jul 27, 1844

Dalton's Atomic Theory
1) All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties 3) Compounds are formed by a combination of two or more different kinds of atoms. 4) A chemical reaction is a rearrangement of atoms. Contributions- the contribution that were contributed by Dalton were all elements consist of atoms which as indestructible. All atoms in an element are the same but the atoms...

J.J Thompson

Sep 15, 1897

Discoveries/contributions
-J.J Thompson was the man to discover the existence of electrons in 1897. Experiments-
The discovery of the electron was found by experimenting with a Crookes, or cathode ray, tube. He demonstrated that cathode rays were negatively charged Spectacular glows could be observed when a high voltage was applied in a gas volume at low pressure. He also experimented with positive charged particles by using neon gas.

Ruthford

Sep 15, 1911

Contributions/Discoveries
Ernest ruthford was a famous New Zealand scientist who made various discoveries involving the splitting of the atom(1717-1919), descibing the half life of a radio active atom, and predicting that the nucleus of an atom if very dense(1911). Experiments-
One of the very well known experiments conducted by the scientist Ruthford was that of shooting alpha radiation particles at an gold foil sheet to prove his theory of nucleus's being very dense. (1911)

Dalton

Jul 27, 1988

Experiments- dalton carried out many experiment on gasses one of which was taking the gasses oxygen and nitric oxide and mixing them to create a third gas.
The results were determined by the proportions or ratios of the two reacting gasses. He carried out these experiments by using the law of multiple proportions and completed the table of atomic weights 2NO + O -> N2O3

Borh

Sep 15, 2016

Discoveries/contributions
Borh made very many discoveries including the discovery of how electrons orbit the nucleus and jump around/orbit differently according to power levels. (1922) Experiments: No experiment could be found that involved Borh.