-
460 BCE
Democritus Atom
Democritus believed that all atoms are small hard particles, are made of a single material formed into different shapes and sizes, and are always moving, and they form different materials by joining together. -
Dalton's Theory
All matter is made of indivisible, indestructible atoms, all atoms of the same element are identical in mass and properties, compounds are formed by a combination of different atoms, and a chemical reaction is a rearrangement of atoms. -
Mendeleev's atomic theory
Creator of the periodic table, and the periodic law. Which states that when elements are arranged according to their atomic number, elements with similar properties will appear at regular intervals. -
Goldstein's atomic contribution
He assisted greatly to the study of cathode rays. He discovered protons in the experiment. They would knock the electrons of atoms and attract them to a positively charged electrode -
Thomson's atomic theory
Thompson discovered the electron in 1897 and was the one that took the plum pudding model of the atom into consideration. -
Planck's Atomic Theory
He discovered hot objects don't emit energy continuously, like in a wave, instead, energy is emitted in small, specific amounts called quanta which became the origin of the quantum theory. -
Rutherford's atomic theory
Gold-foil experiment where he demonstrated that an atom has a tiny but heavy nucleus. -
Bohr's atomic theory
The hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. -
MIllikan's atomic theory
He won the Nobel Prize in 1923 for the measurement of the electronic charge -
Heisenberg's atomic theory
He's associated with the quantum mechanics which he published in 1925 at the age of 23. -
Schrodinger's Atomic Theory
The atomic model is known as the quantum mechanical model of the atom -
Chadwick's atomic theory
Chadwick bombarded beryllium atoms with alpha particles that created an unknown radiation. This particle became neutron.
