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Democritus
Democritus was born in Abdera, Greece in 460BC.His mentor, Leucippus, originally came up with the atomic theory, but it was then adopted by Democritus. The atomic theory stated that “The universe is composed of two elements: the atoms and the void in which they exist and move.”
1.All matter consists of invisible particles called atoms.
2. Atoms are indestructible.
3. Atoms are solid but invisible.
4. Atoms are homogenous.
5. Atoms differ in size, shape, mass, position, and arrangement. -
aristotle
Aristotle did not believe in the atomic theory and he taught so otherwise. He thought that all materials on Earth were not made of atoms, but of the four elements, Earth, Fire, Water, and Air. He believed all substances were made of small amounts of these four elements of matter. Most people followed Aristotle’s idea, causing Democritus’ idea- which was that all substances on Earth where made of small particles called atoms- to be over looked for about 2,000 years! Aristotle's view was finally p -
dalton
His atomic theory said that elements consisted of tiny particles called atoms. It states an element is one of a kind (aka pure) because all atoms of an element are identical. All the atoms that make up the element have the same mass. All elements are different from each other due to differing masses. A compound is a pure (one of a kind) substance due to different
A photo of John Dalton's atomic model
elements bonded together. They are not easily sep -
Rutherford
Rutherford's first researches, in New Zealand, were concerned with the magnetic properties of iron exposed to high-frequency oscillations, and his thesis was entitled Magnetization of Iron by High-Frequency Discharges. He was one of the first to design highly original experiments with high-frequency, alternating currents.
His second paper, Magnetic Viscosity, was published in the Transactions of the New Zealand Institute (1896) and contains a description of Magnetic Viscosity -
jj 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. -
bohr
In 1913, he passed on to a study of the structure of atoms on the basis of Rutherford's discovery of the atomic nucleus, and since 1920 (until his death in 1962) he was at the head of the Institute for Theoretical Physics, established for him at that university.
During his work on the atomic structure, he succeeded in working out and presenting a picture of atomic structure that, with later improvements, still serves as clarification on the physical and chemical properties of the elements.
