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Democritus
The atomic theory stated that “The universe is composed of two elements: the atoms and the void in which they exist and move.” According to Democritus atoms were miniscule quantities of matter. Democritus hypothesized that atoms cannot be destroyed, differ in size, shape and temperature, are always moving, and are invisible. He believed that there are an infinite number of atoms. This hypothesis was created in 465BC. -
John Dalton
John Dalton was seriously interested in meteorology for the longest time. He published Meteorological Observations which was daily weather observations. He did these observations from 1787 until he died in 1844. His serious interest in meteorology led him to his view of atomism. -
J.J Thomson
J.J. Thomson discovered electrons and noticed that an atom can be divided. Also, he concluded atoms are made of positive cores and negatively charged particles within it. He developed the Plum Pudding Model before the atomic nucleus was discovered. This model shows that the electrons are surrounded by a "pudding" of positive charges to balance the negative charges. Today, J.J. Thomson's discoveries have helped people to have a better understanding of the atom and its generic makeup -
Ernest Rutherford
Rutherfords discoveries allowed scienctists to learn more about the world we live in and who we are. Atoms are in every living thing, and with information like this, and information that can be gained in the future, we can learn more about our small part in the universe
Thanks to the discovery, we now know that the only "solid" part of the atom is the atomic nucleus, which disproves the plum pudding model -
Neils Bohr
This model of Bohr’s idea of the atomic structure shows how it works. The nucleus lies in the center of the model and is made up of a certain number of protons and neutrons. Each of the outer layers is made up of a certain amount of electrons. The limit to how many electrons can be in each electron shell is shown in the model. This model helps not only with the theoretical appearance of an atom, but also how different elements combine. -
Robert Milikan
His oil drop experiment helped to quantify the charge of an electron, which contributed greatly to our understanding of the structure of the atom and atomic theory. -
Louis de Broglie
He believed that electrons can act like both particles and waves, just like light. He also said that waves produced by electrons contained in the orbit around the nucleus, set up a standing wave of a certain energy, frequency, and wavelength. He discovered that electrons can act like waves which helped explain some of the things electrons do that we had never been able to explain before. Today, quantum physics is applied in lasers, computers, and microscopes. -
Erwin Schrodinger
Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom. -
James Chadwick
Chadwick bombarded beryllium atoms with alpha particles. An unknown radiation was produced. Chadwick interpreted this radiation as being composed of particles with a neutral electrical charge and the approximate mass of a proton. This particle became known as the neutron.