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440 BCE
Democritis
Democritis was the first person to start the atomic theory. He theorized that everything in the world was made up of tiny particles surrounded by empty space, varying in size and shape depending on what it is constructing. He named these particles atoms, they are uncuttable. They're based off the word atomos, which means indivisible. These atoms are surrounded my empty space but are mostly made with empty space. -
John Dalton
The atomic theory would be forgotten until the year of 1808, he sought to challenge the Aristotelian theory. As Democritis was entirely theoretical, John Dalton showed that the substance will always break up into the same elements. Think water into oxygen and 2 hydrogen atoms. Each atom has it's own size and mass, as atoms cannot be created nor destroyed. -
J. J. Thomson
By this point, the scientific community accepted the atomic theory but it was later revised in the late 1800s. Thomson discovered the electron in an atom. The model was named the "chocolate chip cookie". He showed that atoms are just packed spheres of positive matter, filled with negatively charged electrons. -
Ernest Rutherford
(Didn't specify year) Rutherford was one of Thomson's many students. He got the nickname, "The Father of the Nuclear Age". He started studying the affects of x-rays on gasses, he decided to better study atoms off of this idea. Thomson's model should say that all the particles should go through but some bounced back. Ernest concluded that an atom has few electrons and mostly empty space, and most of the mass is focused in the center. -
Niels Bohr
Another student of J. J. Thomson, Niels drew work from Max Plank and Albert Einstein to revise Rutherford's model later in the 1900s. He suggested that electrons are on a ring like Earth's orbit, but around the atom. Electrons can hop between rings but can only move at a fixed speed. When he took this idea centerstage, he realized that electrons act more live waves, not confined to one particular point in space. -
Erwin Shcrödinger
Erwin Shcrödinger was an austrian physicist who took Bohr's atomic model and stepped forward one whole step. Erwin thought that using math equations to find the likelihood of finding an electron in a certain position, which was thought to be impossible at the time, would and should work. Erwin made his own atomic model called the quantum mechanical model of an atom to show his accomplishment. -
Werner Heisenberg
(Year not specified) The determined that it's truly impossible to determine the position and speed of an electron as they moved around an atom. Electrons cannot be pinpointed but exist within a range of possible locations, this idea gave the rise to the current quantum model of an atom.
