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427 BCE
Plato
Plato believed Used Aristotle's theory, but he used shapes to see what ones can be broke down mathematically. -
400 BCE
Democritus
Democritus thought that atoms are tiny, uncuttable, solid particles that are surrounded by empty space and constantly moving at random -
360 BCE
Aristotle
Aristotle thought that all materials on Earth were not made of atoms, and he believed that all substances were made up of earth, fire, water, and air. Aristotle did not believe in the atomic theory -
Lavoisier
Lavoisier believed that matter was neither created nor destroyed in chemical reactions -
The Alchemists
The alchemists believed that all metals were formed from two mercury and sulfur. -
Jonh Dalton
Dalton proposed that every single atom of a component, like gold, is the same as every other atom of that component. -
Mendeleev's Pd. Table
Mendeleev's table comprehensive system for classifying the chemical elements. He left gaps where there appeared to be an element missing that had not yet been discovered. -
Photoelectric effect
Heinrich Rudolf Hertz made the Heinrich Rudolf Hertz. It's the emission of electrons when electromagnetic radiation, such as light, hits a material. -
Discovery of Radioactivity
Henri Becquerel Discovers Radioactivity. It works by a strongly radioactive elements polonium and radium, which occur naturally in uranium minerals. -
Discovery of the electron
J.J. Thomas discovered the electrons. He experimented with ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. -
Discovery of the proton
Ernest Rutherford discovered the discovery of the proton. He found that these hydrogen nuclei were produced from the nitrogen atoms present in the atmosphere. -
Plum pudding Model
J.J. Thomson's discovered the Plum pudding Model. It is an atom consists of a sphere of positive matter within which electrostatic forces determine the positioning of the negatively charged corpuscles. -
Planck's quantum
Different atoms and molecules can emit or absorb energy in discrete quantities only. -
Rutherford's Gold Foil Experiment
Ernest Rutherford discovered the Rutherford's gold foil experiment. Ruthers gold foil experiment Showed that gold atoms were mostly empty space. -
Robert Millikan
He discovered that all the drops had charges that were simple multiples of a single integer, the electron's fundamental charge. -
Bohr's Planetarily model
The Bohr's Model is structural model of an atom and Niel Bohr's made it. It works by electrons encircle the nucleus of the atom in specific allowable paths called orbits. -
Mosley's Atomic number
Mosley discovered the Atomic Number. It is the number of positive charges in the atomic nucleus -
charger of the Electron
J.J. Thomson's found that all atoms contain tiny negatively charged subatomic particles or electrons. -
Schrödinger equation
The Schrodinger equation assumes that the electron is a wave and tries to describe the regions in space, or orbitals, where electrons are most likely to be found. -
Heisenberg uncertainty principle
Werner Heisenberg discovered Heisenberg uncertainty principle. It states that we cannot know both the position and speed of a particle, such as a photon or electron, with perfect accuracy. -
Discovery of the neutron
James Chadwick discovered the discovery of the neutron. He found that the new radiation consisted of not gamma rays, but uncharged particles with about the same mass as the proton. -
New Lands Law of Octaves
An English chemist, John Newlands made the New Lands Law of Octaves. It worked by when Elements are arranged in increasing order of Atomic Mass, the properties of every eighth Element starting from any Element are a repeating of the properties of the starting Element.