-
430 BCE
Democritus
Leucippus of Miletus is thought to have originated the atomic philosophy. -
360 BCE
Plato
Democritus lived about two hundred years before Aristotle and Plato, and is often credited with originating the concepts of the atom. He was a philosopher, and his idea was to try to explain why different materials had different properties, such as why are liquids flexible and solids less flexible. -
322 BCE
Aristotle
He made pioneering contributions to all fields of philosophy and science, he invented the field of formal logic, and he identified the various scientific disciplines and explored their relationships to each other. Aristotle was also a teacher and founded his own school in Athens, known as the Lyceum. -
lavoisier
Antoine Lavoisier's atomic theory model was grounded in the law of conservation of mass explaining matter was conserved during chemical changes. His experiments also shaped the idea that matter was composed of chemical compounds. -
John Delaton
Dalton hypothesized that the law of conservation of mass and the law of definite proportions could be explained using the idea of atoms. He proposed that all matter is made of tiny indivisible particles called atoms. -
The alchemists
This is the contention of William Newman, professor of history and philosophy of science at Indiana University. He maintains that alchemists, especially the 17th-century Robert Boyle, provided proof of atoms and therefore laid the foundations of the contemporary science. -
Newton's new land of octaves
Its when elements are arranged in increasing order of atomic mass. -
Mendeleev's Pd. Table
There are 118 elements on the table. Out of the 118 elements 94 are natural elements. -
Photoelectric effects
It was discovered by a German physicist Hinrichs Rudolf Hertz. -
Who discovered radioactivity?
Henri Becquerel discovered it. Its one of the most well known accidental discoveries in history of physics. He opened a drawer and found the spontaneous radioactivity. -
Who discovered the electron?
Joseph John Thomson discovered it by experimenting with crookres or cathode ray tub. -
Planck's Quantum Theory of Light
According to Planck's quantum theory, Different atoms and molecules can emit or absorb energy in discrete quantities only. The smallest amount of energy that can be emitted or absorbed in the form of electromagnetic radiation is known as quantum. -
Plum Pudding Model
The plum pudding model depicts the electrons as negatively charged particles embedded in a sea of positive charge. The structure of Thomson's atom is analogous to plum pudding. -
Rutherford's gold foil Experiment
its when a piece of gold foil was hit with alpha particles, which have a positive charge. Most alpha particles went right through. This showed that the gold atoms were mostly empty space. -
Robert Millikan
Roberts earliest major success was the accurate determination of the charge carried by an electron, using the elegant “falling-drop method” -
Bohr's Planetary Modle
The Bohr Model is a structural model of an atom. The model was proposed by physicist Niels Bohr in 1913. In this model, the electrons travel around the nucleus of an atom in distinct circular orbits, or shells. The model is also referred to as the planetary model of an atom. -
Mosley's Atomic Numbers
Mosley published a paper in which he said that the atomic number is the number of positive charges in the atomic nucleus. He also proved that there are three unknown numbers. -
Who discovered the proton
Ernest Rutherford discovered the proton in 1919 after a spilling of the atom. -
Charge of electrons
Robert Millikan discovered charge of electron and won Noble prize in physics in 1923. In 1909, American physicist R. Millikan measured the charge of an electron using negatively charged oil droplets. -
Schrodinger Equation
Erwin Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom. -
Heisenberg Uncertainty Principle
It was made by a German physicist he states that "we cannot know both the position and speed of a particle, such as a photon or electron, with perfect accuracy; the more we nail down the particle's position, the less we know about its speed and vice versa." -
Who discovered the neutron?
James Chadwick discovered the neutron because he believed that alpha particles did not have enough energy to produce so much power as they did so he did an experiment on himself.
