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Period: 320 to
History Of The Atom
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350
Democritus
Democritus lived in Abdera, and worked in Egypt, Ethiopia, Persia and India during 460 BCE 370 BCE.Democritus was the first scientist to produce the theory of the atom. He discovered that all matter is full of microscopic particles that we call atoms, which are both solid and indestructible. The word atom comes from Greek ‘atomos’, which means ‘uncuttable’.Democritus laid the groundwork; the building blocks, which many future scientists worked on achieve the atomic theory. -
400
Aristotle
Aristotle was a Greek philosopher, and many of his ideas and thoughts were scientifically based. Because of this, Aristotle strongly disagreed with Democritus. He believed that there was no smallest part of matter and that all substances were made of either earth, air, fire and water. Due to his ignorance of atoms, Aristotle did not have his own atomic model. -
Isaac Newton
Isaac Newton was a physicist and mathematician who is very well known and called one of the most influential scientists in history. He is a key figure in the scientific revolution, and created the laws of gravity and proposed a mechanical universe with small solid masses in motion. -
John Dalton
John Dalton lived in Eaglesfield, England.As a young man, John Dalton was highly influenced by Elihu Robinson, an intelligent meteorologist and instrument maker, who got him keen to learn about mathematics and meteorology.In 1803, Dalton invented the concept of Daltons Law of Partial Pressures, as well as explaining the behaviour of atoms in terms or the measurement of weight. -
Michael Faraday
Michael Faraday studied the effect of electricity on solutions, and found out that electrical forces were responsible for the joining of atoms in compounds.He made one of the most significant discoveries that led to the idea that atoms had an electrical component. -
Henri Becquerel
Henri Becquerel was born into a family of scientists, so was influenced by his father and grandfather to work on the properties or the atom, such as magnetism and radioactivity. His greatest achievements were in the study of radioactivity. He worked with light and the absorption of light by crystals. His discovery of radioactivity allowed future scientists to perfect the atomic model. -
J.J Thomson
Thomson discovered and proved that atoms actually were divisible and were made up of even smaller atoms. Thomson said that the atom could be compared to a plum pudding. The positively charged material is the cake and the electrons are the fruit. This theory is called the Tomson plum pudding model. His experiment showed that the inside of the atom are negatively charged particles. We call them electrons, and they are far smaller. -
Ernest Rutherford
Rutherford later on tested Thomson theory, a found out it was incorrect. He created the nucleus, saying that instead of the whole of the atom being positive matter, it was just the middle. He proved that the atom was mostly empty space and electrons surrounded the nucleus. His model influenced one of his own students to later on perfect the atomic model. -
Marie and Pierre Curie
Marie and Pierre Curie were a couple that added to atomic chemistry by exploring radioactivity. After the discovery of radiation by Henri Baquerel, the couple decided to dig a little deeper. Her and her husband soon found the elements radium and polonium, and later added to the atomic model. -
Max Planck
Max Planck was the scientist who created the Quantum Theory. In this theory, the German man said that all energy was given off in little packets of energy, which were called photons (when talking about the light). His discoveries led to the knowledge of energy levels in atoms. This discovery later helped to move forward in the atomic theory. -
Niels Bohr
With the help of Rutherford’s theories, Bohr published his own model about the atom structure in 1913. He introduced the theory that electrons travelled on orbit around the atoms nucleus, and the outer orbits holding more electrons than the inner ones. This became the basis for quantum theory.His work has both greatly changed and influenced our understanding of physical reality. -
Henry Mosely
Henry Mosely worked along side Niels Bohr to create the real atomic number. Mosely used X-rays to figure out the frequencies of elements for the periodic table. Before this, the elements were assigned random atomic numbers. By using the frequencies to find the atomic numbers, this created Mosley’s Law. -
Erwin Schrödinger
Erwin Schrödinger disagreed with Bohrs theory, so he created his own. He thought that the only way to find the location and energy of an electron in an atom was to calculate its probability of being a certain distance from the nucleus. This equation influenced the Quantum mechanical model of the atom. -
Werner Heisenberg
Werner Heisenberg was a German Scientist that said one couldn’t know the exact location of the electron, as they don’t know the velocity and momentum of the electron at the same time. This principle proves error in Bohr’s model because of the unknown location of an electron. -
James Chadwick
James Chadwick continued with Rutherford’s discovery, and developed it even further. While using alpha particles, he discovered a neutral atomic particle with a mass close to a proton, thus was discovered the neutron.James Chadwick perfected the atomic theory, thus helping the scientific community.
