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Democritus's discovery
(Date isn't accurate)Philosopher Democritus has the idea that all things were made of small little particles. He named these particles “Atomus,” which means indivisible or unbreakable. Another philosopher, Aristotle, disagreed with him and with his disagreement, the idea of the atom was lost for another 2000 years. -
Microscocpe invented
( Not exact date but exact year ) During this year, the microscope was invented. This allowed us to see small particles such as a grain of sand. -
Amedeo Avogadro's Concept of Molecule
A French chemist, Amedeo Avogadro, had the concept of a molecule. His concept was a group of atoms join together forming a molecule. An example of this is 2 Hydrogen atoms and 1 Oxygen atom join together, forming the water molecule, H2O. -
John Dalton's Theory
A chemist named John Dalton revived the idea of the Atom. He believed that Democritus’s idea was right, that billions of atoms bunch up together to form objects. He performed experiments with various chemicals that showed that matter, indeed, seem to consist of elementary lumpy particles (atoms). Although he did not know about their structure, he knew that the evidence pointed to something fundamental. -
Henri Bequerel discovers Radioactivty.
Henri Becquerel discovered radioactivity by using naturally fluorescent minerals to study the properties of x-rays. He placed uranium out in the sun and it emitted xray. He thought the energy of the sun was being emitted from the uranium. Later he tested it again on a cloudy day and found out the uranium was actually emitting its own xray, discovering xray. -
J.J. Thompson's atom model
In 1897, the English physicist J.J. Thomson discovered the electron and proposed a model for the structure of the atom. Thomson knew that electrons had a negative charge and thought that matter must have a positive charge. His model looked like raisins stuck on the surface of a lump of pudding. His model was named "Plum Pudding" -
Marie and Pierre Curie discovers Radium
Fascinated with Henri Becquerel’s discovery of radiation, two French scientists named Marie and Pierre Curie discovers new element that gives off more radiation. This element is known as Radium -
Einstein's E=mc^2
Albert Einstein discovers new law. His theory showed that every mass had a tremendous amount of energy. This theory is how the famous equation, e=mc^2, came to be. -
Earnest Rutherford discovers empty space of the atom.
• Lord Ernest Rutherford put a small piece of radium in a lead shell that has a hole. The rays couldn’t escape except for that small hole. Rays were shooting out of that hole and to a solid object. Rutherford placed a gold thin object in front of it and the ray passed through it. Sometimes, 1 out of the 1000 rays ricochet into the distance. He conclude that an atom is empty space. All except the middle which he called the nucleus. -
Discovery of the atomic split
Two German scientists were trying to find more about uranium by using atomic bullets. The bullets they used were neutrons, which shot out of the nucleus. The neutron hit another nucleus, causing it to split and releasing two more neutrons. Those neutrons hit more nucleuses, causing a chain reaction. That chain caused an atomic explosion. -
Period: to
Discovery of quarks
• In the mid 1900’s, physicists discovered many Particles. In 1964 Gell-Mann went further and proposed the existence of a new level of elementary particles and called them "quarks." He thought there were only three quarks: up, down, and strange. From 1974 thru 1984, three more quarks were theorized called charm, bottom, and top.
