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350
Aristotle
Aristotle came up with the method of gathering scientific facts, which proved as the basis for all scientific work -
400
Democritus
Democritus said that all matter is made up of particles called "atomos". He also stated that atoms are eternal and invisible and so small that they can’t be divided, and they entirely fill up the space they’re in. -
Antoine Lavoisier
Antoine Lavoisier formulated the law of conservation of mass, which is that the total mass in a chemical reaction remains constant. He also distinguished between an element and a compound. -
John Dalton
John Dalton provided the atomic theory, which states that all matter is composed of tiny, indestructible particles called atoms that are indestructable and have no internal structure. He built on the ideas of Democritus. -
Henri Becquerel
Becquerel discovered radioactivity when he investigated uranium and other radioactive substances. He discovered this while While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very pentrating rays. -
J.J Thomson
Thomson discovered the electron and developed the plum-pudding model of the atom. He pictures electrons enclosed in a sphere of positive electrical charge. -
Marie & Pierre Curie
The Curies discovered the elements radium and polonium when they started to investigate radioactive substances. They stated that radioactive materials cause atoms to break down spontaneously, releasing radiation in the form of energy and subatomic particles. and they called this process "radioactivity" The curies worked alongside Henri Becquerel. -
Max Planck
Planck came up with the model of quantized energy. He figured that energy is given off in little packets of energy, instead of being given off in continuous waves. These ideas he came up with are now known as the quantum theory. -
Robert Millikan
Millikan found out through an oil drop experiment the electric charge of the electron, which led to the calculation of the mass of the electron and positively charged atoms. -
Ernest Rutherford
Rutherford used the results of his gold-foil experiment to state that an atom has a small, dense positivelly charged nucleus with electrons moving around the nucleus. -
Neils Bohr
Neils Bohr Proposed that electrons traveled in fixed paths around the nucleus. Scientists still use the Bohr model to show the number of electrons in each orbit around the nucleus. -
Henry Mosely
Mosely sorted the elements of the periodic table in a more logical manner by redefining the idea of atomic numbers. This provided a set of data that proved Earnest Rutherfords model of the atom, where there is a positively charged nucleus that tells the atomic number and its surrounded by negatively charged electrons. -
Erwin Shroedinger
Shroedinger introduced the Shroedinger Equation, a wave equation that describes the form of the probability waves that govern the motion of small particles and how these waves are altered by external influences. -
Werner Heisenberg
Heisenberg came up with the “uncertainty principle”. He also discovered that its impossible to determine the position and momentum of a particle at the same time. He also came up with the “cloud” model aka quantum mechanical model -
James Chadwick
Chadwick discovered the neutron which has no charge. He concluded that atomic nuclei contain neutrons and positively charged protons.
