SCIENCE: THE ATOMIC THEORY

• atom is considered the smallest particle of matter
• Atomic model is a representation of what an atom could look based on observations and scientific evidence that describe how atoms behave
• Democritus expressed his belief that matter consists of very small, indivisible objects, which then he described as atomos
• Aristotle believed that matter was made up of four natural elements
• John Dalton, an English physicist, proposed the first atomic theory after conducting a number of experiments about atoms, which he wrote in his book A New System of Chemical Philosophy. He viewed atoms as solid spheres, which he believed had four characteristics.
• A subatomic particle is a particle smaller than an atom in which scientists used experimental observations to establish its existence.
• Joseph John Thomson was able to discover electrons from his observations in his cathode ray tube experiment
• A cathode ray tube is a glass tubing with two electrodes, namely, the anode (+) and the cathode (-), at each end.
• Plum Pudding Model : chocolate-chip cookie model
• Robert Millikan : oil drop experiment
• Ernest Rutherford : gold foil experiment
• Niels Bohr : planetary model
• James Chadwick : Neutrons