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427 BCE
Plato
He discovered the atomic theory which can be described as an ideal geometric form served by atoms which is when atoms mathematically break into triangles, such that the form elements had the following shape: fire(tetrahedron), air(octahedron), water(icosahedron), earth(cube) -
400 BCE
Aristotle
he pioneered or brought along the techniques of logic, observation, inquiry and he also taught demonstration. -
400 BCE
Democritus
Democritus created the thought of that everything is made up of invisible atoms. This is called the Atomic Theory -
The Alchemists
They came across some new elements like fire, earth, water, air, mercury and sulfur. -
Lavoisier
He introduced the role oxygen plays in combustion. He also acknowledged and named oxygen and hydrogen. -
John Dalton
He introduced the atomic theory. This theory states that indivisible particles make up all matter. Also, that the atoms of each element are the same looking. -
New Land of Octaves
It states when elements are in order increasingly by atomic mass, the properties of every Eight element beginning with any element are a repetition of properties of the starting element. -
Mendeleev's Periodic Table
His table may be different because instead ordering the elements by atomic number they are ordered by mass. -
Photoelectric Effect
Heinrich Rudolf Hertz discovered the photoelectric effect, and he was a German physicist -
Discovery of Radioactivity
Henri Becquerel discovered radioactivity as one of the most well known accidental discovery -
Discovery of the electron
J.J. Thomson also discovered the electron he is a British physicist opened the door to a physical scientific revolution that has since given rise to modern theories about atomic structure and chemistry. -
Planck's Quantum Theory of Light
This theory is saying that the filaments of a lightbulb should be heated up to about 3200 Kelvin to make sure the most energy can be emitted. -
Plum Pudding Model
J.J. Thomson made this historical scientific model of the atom, According to the "plum pudding" model, electrons are enclosed in a region of positive charge, just like negatively charged "plums" are contained within positively charged "pudding." -
Rutherford's Gold Foil Experiment
The positive-charged alpha particles struck a piece of gold foil. Most alpha particles passed through unharmed. This demonstrated that the gold atoms primarily consisted of empty space. -
Charge of Electron
Robert Millikan discovered the charge of the Electron. He did this by using negatively charged atoms. -
Bohr's Planetary Model
the electrons move around the nucleus of the atom in certain paths called orbits. When the electron is in one of these orbits, its energy is fixed. -
Robert Millikan
Millikan determined the charge carried by an electron. He found this out by using the "oil drop experiment". Using this experiment he later found out the mass of an electron. -
Mosley's Atomic Number
Mosley discovered that the atomic number is the number of positive charges in an atomic nucleus. He also found out that there are three unknown elements, and there atomic numbers are 43, 61, and 75. -
Discovery of the Proton
Ernest Rutherford discovered the proton, he named it after the Greek word of "protos" -
Schrodinger Equation
The Schrödinger equation is also known as a linear equation that governs the wave function of a quantum-mechanical system, and it was made by Erwin Schrodinger. -
Heisenberg Uncertainty Principle
Heisenberg was a German physicist and the principle states that we will not know two of the position and speed of a particle, such as a proton or electron, with perfect accuracy -
Discovery of the neutron
James Chadwick discovered the new uncharged particle also known as the neutron
