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Democritus made an ancient atomic theory. He stated that everything is made up of small invisible atoms. -
Plato made a theory that stated atoms broke down into triangles to form bigger shapes(elements). -
Aristotle said that mixing two substances of comparable amounts are called compounds. -
People who wanted to manipulate the properties of matter to get more valuable substances. -
Discovered the role of oxygen in combustion. Named the element Hydrogen. -
Stated that all matter is made of atoms which are invisible. -
Stated that elements organized by increasing atomic weight will have similar chemical and physical properties every 7 elements. -
Found the elementary charge of electrons using the oil drop experiment. -
He realized elements physical and chemical properties were related to their atomic mass. He then made a table to show this. -
When electrically charged particles are released from material when it absorbs electromagnetic radiation. -
Scientists were researching cathode rays for electrical properties in matter. -
Says that light bulb filaments should be heated to 3200 kelvin so the energy is emitted as visible waves. -
The scientific model of an atom. "Plums" were the negative charge inside the "pudding" a positively charged area. -
The electron is the lightest stable subatomic particle known. It has a negative charge of 1.602176634 × 10−19 coulomb. -
Gold foil was hit with positively charged alpha particles. Most particles went through the foil proving gold atoms were mostly empty space.
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Showed that electrons orbit the nucleus. -
Stated the atomic number is the number of protons in an atom. -
Ernest Rutherford split atoms and discovered the proton. -
An equation that showed where an electron would be at any given moment. -
We cant know both the position and speed of the particle. -
James Chadwick discovered the neutron. He believed alpha particles did not have enough energy to produce powerful gamma rays. He found particles that have the same mass as protons but no charge. -
Accidently discovered by Henri Becquerel when studying x-rays.
