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Plato had a theory that was that atoms are geometric forms and vise-versa. He believed that all atoms could mathematically break down into shapes. The shape correlated to the four main elements. the elements were air=octahedron, earth=cube, fire=tetrahedron, and water=icosahedron. -
In 400 BCE, Democritus had believed that everything was made of atoms that were hard, solid, and incompressible. He also believed that atoms constantly moved in infinite numbers until they were stopped. -
Aristotle did not believe in atomic theory instead he believed that everything was made from the elements. Elements such as fire, air, water, and earth. -
In the 17th century, the alchemists created things such as gunpowder, glass and ceramics, ink, dyes, and paints. They made these things by blending the principles of water, fire, air, and earth, and of mercury, sulfur, and salt. Many people call them the "predecessor" of chemistry. -
Lavoisier had many discoveries but here a few of his most major ones. Lavoisier defined the law of conservation of mass, which his definition is that all matter was composed of atoms that were not destroyed or created during chemical reactions. He also claimed that water was not an element but a compound of oxygen and hydrogen. -
John Dalton's atomic theory is in three parts the first part is stated that all matter is made of atoms, which are indivisible. The second part of his theory states that all atoms of a given element are the same in mass and it's properties . And lastly, the third part says that compounds are combinations of two or more different kinds of atoms. With this he created the atomic theory. -
the English chemist John Newland had arranged 62 elements that were known at the time into an ascending order according to their atomic weights. Then he discovered that in every 8th element the weights were the same. -
Mendeleev created the periodic table by placing the elements in the order of their atomic weights. -
Heinrich Hertz discovered the photoelectric effect. This happens when electrically charged particles are released form a material when it takes in electromagnetic radiation. -
Henri Becquerel discovered on accident, spontaneous radioactivity. With this discovery he connected that a mineral that contains uranium would darken a photographic plate with no light. -
The founder of the charge for an electron was J.J Thomson. He found it by using cathode ray/tube to determine that the rays were negatively charged. -
Made by J.J. Thompson he made this discovery by realizing that the model of an atom didn’t account for particles negatively charged or positively charged. -
Plank's theory explains the the light bulb filaments need to be heated to around 3,200 Kelvin to make sure the energy is seen as visible waves. He also claimed that energy is radiated every minute -
This was made by J.J. Thompson and he defined it as, electrons surrounding a positive charge. But he was not correct. people didn't know this at the time so, it was used as the basis for other scientists’ models. -
Rutherford made this experiment by having a piece of gold foil get hit with alpha particles, which are protons. Almost all the particles went through the foil. This result showed that the gold atoms were mostly empty space. So the results were that the atom is a small, dense, positive charged nucleus, that is mostly empty space. -
Robert Millikan discovered the accurate charge carried by and electron and he also proved that the charge for the electrons is a constant for all electrons -
Bohr's model shows that electrons exist on the outside of the nucleus; encircling it. He named the paths the electrons follow orbits. -
Henry Mosely discover that the atomic number in an element is the same as the number of protons. Then he also claimed that there were three elements that were unknown, with the atomic numbers 43, 75, and 61. -
This discovery was made by Ernest Rutherford. He made his discovery by using the Gold Foil experiment. The way he found the proton was by creating a small nuclear reaction, which made the atom split, that is how he discovered protons. -
Erwin Schrodinger made an equation to find the wave function of a system and the changes it makes in time which was very important to quantum wave mechanics. and it detected where exactly the electron could be at any time. -
Heisenberg's principle is that we won't know both the speed and position of a particle like electrons/protons with accuracy. and the more you try to find the speed of the particle, the less you will know about the position of the particle. -
James Chadwick discovered the neutron. He found the neutron by realizing that the core of the nucleus contains an uncharged particle.