432 BCE- Empedocles

Empedocles was responsible for separating air as a separate substance. In his beliefs air, fire, water, earth mingle and separate under the compulsion of love and strife.

440 BCE- Democritus

Democritus’s theory was the first theory to be contributed to the atomic theory. He proposed that the entire world was made up of tiny particles surrounded by an empty space. He also said that they were invisible physically but not geometrically. He called these particles Atomos.

440 BCE- Aristotle

Aristotle’s contribution was completely different; he disagreed with Democritus and stated that particles comprise the four elements instead. And most scientists believed him over Democritus.

500 BCE- Alchemists

Alchemists developed the idea that all metals are composed of mercury & sulfur and that changing base metals into gold is possible.

1803- John Dalton

John Dalton’s contribution was that he reintroduced the idea of particles, which vary in shape and size based on the substance type and the mass and volume of this substance. He also showed that common substances always broke down into the same elements and the same proportion they were in previously.

1831- Michael Faraday

Faraday’s discoveries led to the idea that atoms had an electrical component. In his experiment, he placed two opposite electrons in a water solution containing a dissolved compound.

1897- J.J. Thomson

Thomson’s contribution was the discovery of the electron. He also created the Plum Pudding Model. He believed inside an atom were negative and positive particles mixed with a positive between each negative.

1911- Ernest Rutherford

Known as the father of the nuclear age. Rutherford discovered that atoms are mostly surrounded by an empty space, with just a few electrons, while most of the mass was in the center, which he termed the nucleus.

1913- Niels Bohr

Bohr’s contribution was expanding on Rutherford’s model and discovered that the electrons circle the nucleus at fixed energies and distances and can jump from one level to another but not exist in the space between.

1932- Sir James Chadwick

Chadwick was responsible for discovering the neutron in atoms. Neutrons are located at the center of an atom in the nucleus. They have neither a positive nor negative charge but the same weight as a proton.

1938- Lise Meitner

Meitner discovered that nuclear fission can produce enormous amounts of energy. She was discovered in Sweden after she escaped Nazi Germany. After World War 2 ended, she was named the mother of the atomic bomb.

1948- Maria Goeppert-Mayer

Goeppert-Mayer was responsible for presenting the nuclear shell model of the atomic nucleus. She was the second woman to receive the Nobel Prize for physics

author avatar
William Anderson (Schoolworkhelper Editorial Team)
William completed his Bachelor of Science and Master of Arts in 2013. He current serves as a lecturer, tutor and freelance writer. In his spare time, he enjoys reading, walking his dog and parasailing. Article last reviewed: 2022 | St. Rosemary Institution © 2010-2024 | Creative Commons 4.0

Leave a Reply

Your email address will not be published. Required fields are marked *

Post comment