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428 BCE
plato
a Greek philosopher born in Athens during the Classical period in ancient Greece. He believed in the existence of an immaterial world of perfect objects and ideas -
384 BCE
Aristotle
Greek philosopher during the Classical period in ancient Greece, taught by Plato. -
460
Democritus
He was an ancient Greek pre-Socratic philosopher, and was one of the original founders of ancient atomist theory. -
Lavoisier
He discovered the role of oxygen in combustion and respiration, proved the law of conservation, reformed the chemical nomenclature, and named hydrogen. He is known as "the father of modern chemistry". -
John Dalton
English chemist, physicist, and meteorologist. Created the atomic theory, which states that all matter was comprised of indivisible and indestructible atoms with distinct masses and properties, the combination of which determined the physical nature of their constituent elements. -
The Alchemists
They believed that all metals were formed from two principles: mercury and sulfur. The mercury gave rise to the malleability of metals and the sulfur contributed to the rusting -
newlands law of octaves
created by J.A.R Newlands- if the chemical elements are arranged according to increasing atomic weight, that those with physical and chemical properties that are alike occur after each interval of 7 elements. -
Robert Millikan
He was a physicist who discovered the elementary charge of an electron using the oil-drop experiment. -
Mendeleev's Pd. Table
Created by Mendeleev, he put these elements in order of increasing weight and broke them into rows. -
photoelectric effect
a phenomenon discovered by Heinrich Rudolf Hertz where electrically charged particles are released from/within a material when it absorbs electromagnetic radiation -
discovery of radioactivity
discovered by Henri Becqueres-- he opened his drawer and discovered spontaneous radioactivity -
discovery of the electron
J.J. Thomson experimented with cathode ray tubes which showed that all atoms contain tiny negatively charged subatomic particles or electrons. -
Planck's Quantum Theory of Light
This theory states that light bulb filaments should be heated to a temperature of about 3,200 Kelvin to ensure that most of the energy is emitted as visible waves. -
plum pudding model
historical model of the atom proposed by J.J. Thomson -
rutherfords gold foil experiment
a piece of gold foil was hit with alpha particles, and those have a positive charge. Most of the alpha particles went all the way through. this showed that the gold atoms were mostly empty space. -
bohr's planetary model
the electrons encircle the nucleus of the atom in specific paths called orbits -
Mosley's Atomic Numbers
In 1914, Moseley published a paper where he concluded that the atomic number is the number of positive charges in the atomic nucleus. -
discovery of the protons
discovered by Ernest Rutherford- his research resulted in a nuclear reaction which led to the first "splitting" of the atom, discover protons. -
Charge of the Electron
It was discovered by Robert Millikan. He charged droplets of oil between two eletr and balanced the gravitational force with the upward forces. He used mechanical equilibrium to determine the charge, which he found within one percent of the current accepted value. -
Schrodinger Equation
A linear partial differential equation that governs the wave function of a quantum-mechanical system. -
heisenberg uncertainty principle
created by werner heisenberg, this principle states that we cannot know both the speed and position of a particle -
discovery of the neutron
Was discovered by James Chadwick by using scattered data to calculate the mass of the neutral particle