Timeline
History of the Atom
460 BCE
Democritus is born in Aldera, Greece
The history of the atom starts a long time ago just about 2,000 years before the invention of the first microscope and almost 2,500 years from now
Democritus was an ancient greek pre-socratic known as the laughing philosopher since he emphasized cheerfulness
He is mostly known for his development of an atomic theory of the universe
370 BCE Democritus dies around the age of 90
He knew that if a stone was split in half, both sides would still have the same properties as the whole so he proposed that if the stone was continually cut in half it would get so small that they wouldn't be able to cut it anymore
He called these small pieces "atomos" after the greek word for indivisible
Unfortunately his theory was rejected by Aristotle, who was one of the most influential philosophers at the time and so Democritus' atomic theory was ignored
2,000 years later
1743
Antoine Lavoisier is born in Paris, France
Antoine Lavoisier Was a leading figure during the 18th century chemical revolution
May 5, 1789
The French Revolution begins
Lavoisier unfortunately having served as a financer and public administrator before the french revolution he was executed along with other financiers
He measured the starting materials before and after a chemical reaction and found that the mass stayed the same
With this he created the law of conservation of mass which states that the total mass of 2 objects stays the same before and after a chemical reaction
We now know why mass stays the same because atoms can't be created or destroyed
John Dalton was an english chemist, physicist, and meteorologist
1794
Antoine Lavoisier is guillotined
1844
John Dalton dies
1766
John Dalton is born in Eaglesfield, UK
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He is mostly known for introducing the atomic theory into chemistry
He is also known for his contributions to color blindness which is sometimes referred to daltonism in his honor
He proposed that all matter either, solid, liquid, or gas was made up of small indestructible particles known as atoms
He discovered this through experiments on gases that haven't been possible until the 19th century
J.J Thomson was a British Physicist
1856
J.J. Thomson is born in Cheetham Hill, Manchester, United Kingdom
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1858
Max Planck is born in Kiel, Germany
He discovered the Electron, the very first subatomic particle to be discovered
Max Planck was a German theoretical physicist who won a nobel prize due to his discovery
He discovered it after experimenting with a cathode ray tube and by doing this he discovered positive and negative charged particles
Cathode Ray tube
1859
Pierre Curie is born in Paris, France
He created the theory that energy did not flow in a steady continuum but was instead delivered in discrete packages he called Quanta
Max Planck also met with Hitler once to ask him to stop attacking Jewish scientist
His work laid the foundations for Quantum Theory
Marie and Pierre Curie discovered the very strong radioactive elements polonium and radium
1867
Marie Curie is born in Warsaw Poland
The element Polonium was named after Marie's home country, Poland
Marie created the word radioactivity for the sudden release of ionizing, penetrating rays of certain atoms
They discovered Polonium and Radium in their research of pitchblende which is a form of the mineral Uraninite
Robert Millikan was an American experiment physicist
1868
Robert Millikan is born in Morrison, Illinois
1871
Ernest Rutherford is born in Brightwater, New Zealand
With an experiment he did he was able to find the charge of an electron
He was given a nobel prize for his discovery in 1923
In his "oil drop" experiment he had created microscopic oil droplets that could be electrically charged with friction or X-rays
The droplets could have been slowed down or reversed by an electric field lower in the system so by adjusting this electric field he was able to calculate the charge on each individual drop
Ernest Rutherford was a British physicist who is known today as the father of nuclear physics
1879
Albert Einstein is born in Ulm, Germany
He discovered the Atomic nucleus and developed a new model of the atom similar to our solar system
He discovered alpha and beta rays and he also proposed the laws of radiation
He discovered the nucleus by sending high speed and positively charged alpha particles at a thin piece of gold foil and then examined where the particles went using a luminescent screen that glowed when the particles hit it.
What he found was that some of the particles went straight through while a small amount was deflected
he determined that the volume of an atom consists a large amount of empty space and that there is a small positively charged body (the nucleus) at the center of each atom
Rutherford's model
1885
Niels Bohr is born in Copenhagen, Denmark
Albert Einstein was a very famous physicist and may as well be the greatest physicist of all time
1905 was a big year for Einstein, He published his special theory of relativity, his general theory of relativity, and created his famous e=mc^2 equation
What he did to contribute to the atomic theory was mathematically prove the existence of atoms in 1905
He did this by observing a visible object immersed in invisible randomly jostling molecules and measured the motion of the visible object as it is pushed around in random directions
Niels Bohr is a danish physicist who made major contributions to understanding atomic theory and quantum theory
1887
Erwin Schrödinger is born in Erdberg, Vienna, Austria
In 1920 Niels Bohr founded the institute for Theoretical Physics which was sponsored by the Carlsberg Brewery
He proposed to add the new idea of Quanta to the model so that the electrons were at set levels of energy
He proposed this idea due to the fact that according to classical physics the electrons orbiting the nucleus should lose energy until they spiral towards the center and collapse the atom
Erwin Schrödinger was an Austrian Physicist who used mathematical equations to describe the likelihood of finding an electron in a certain location
1891
James Chadwick is born in Bollington, UK
His model doesn't describe the exact path of an electron but rather predicts the odds of the location of the electron
1892
Louis De Broglie is born in Dieppe, France
James Chadwick was a British physicist that discovered the third part of the atom, the neutron
After only 2 weeks of testing he published a paper called "the possible existence of a neutron" in which he proposed his idea of the neutron
During his time other scientist had begun to blast beryllium with alpha particles and studied the highly penetrating radiation it was producing but chadwick noticed something odd about the radiation
After some testing he was sure that the particles being emitted was a neutral particle similar to the mass of a proton
he called this particle a neutron and was later able to determine that its mass is slightly greater than a proton
Louis De Broglie was a french physicist and a aristocrate
1901
Werner Heisenberg is born in Würzburg, Germany
Werner Heisenberg was a German theoretical physicist and a key pioneer in quantum mechanics
He introduced the idea that particles, like electrons could be described as waves and not just particles
This was proven by the way streams of electrons were reflected against crystals and spread through thin metal foils
1905
Albert Einstein proves the existence of Atoms mathematically
Werner is the youngest and last one on this long list of all the people, who over the years have helped develop the atomic theory
He discovered the uncertainty principle which basically states that a particles position and momentum can't be known exactly
He discovered this by coming to the realization that the more accurate someone tried to measure the position then the more uncertain the momentum would be and this effect worked both ways
1906
Pierre Curie dies
1923
Robert Millikan is awarded the nobel prize for his discovery
1932
James Chadwick discovers the neutron
1934
Marie Curie dies
1937
Ernest Rutherford dies
1940
J.J. Thomson dies
1947
Max Planck dies
1953
Robert Millikan dies
1955
Albert Einstein dies
1961
Erwin Schrodinger dies
1962
Niels Bohr dies
1974
James Chadwick dies
1976
Werner Heisenberg dies
1987
Louis De Broglie dies
To present day -->
J.J. Thomson's "Plum Pudding" model
Dalton's atomic model Link Title
Bohr's atomic model
Unfortunately people can't live forever other than in memory so even though some of the greatest minds, that have been ever seen, are gone now, they have laid the foundations for future researchers to work and build upon