The first step in discovering the atomic theory took place in the late 1800’s with John Dalton an ancient Greek. The mass number is the same number of particles in the nucleus, which is sometimes referred to as Dalton (DA). (Book) Democritus stated that all matter was made up of atoms, which he called atomos. (Early Ideas Prezi) Aristotle seemed to disagree with him. Democritus said that atoms moved through empty space, which Aristotle said did not exist. (Early Ideas Prezi)
These experiments were the fundamental building blocks needed to come up with this theory. It began with Sir William Crookes who accidently discovered the cathode ray. …show more content…
(From Timeline) It also helped to discover small cells like the corpuscle. The corpuscle is a very small particle that is unattached in a cell. It also enabled other things to be discovered, such as a positron. A positron has the same atomic mass as an electron, but with a positive charge. Quarks and leptons are things that build mater. A strange quark is a quark with a collision that lasted ten times longer than expected. A top quark is the heaviest of all the quarks, therefore has the shortest life expectancy. A lepton decays in order to make a positron. P+ is the symbol that can be used to represent a proton or a positron. When the air was sucked out of the discharge tube, he knew that the negative charge had to come from somewhere. (From Timeline) This led to J.J Thomson winning the Nobel prize. J.J Thomson also came up with the plum pudding model. This showed the spherical cloud and the electrons throughout. It was nicknamed the plum pudding model as it resembles the appearance of plum pudding with electrons shown throughout. (Book) The next experiment that helped mold the atomic theory in the 1900’s was Millikan’s oil drop test. Millikan performed this experiment in 1909. This made it possible to calculate …show more content…
(Book) In the present day model, it shows that electrons are located in orbitals. These orbitals may sometimes be known as electron clouds, as they do not have a set boundary, this can be shown in the cloud model. This is also known as the quantum theory. This assigns energy levels to all of the electrons. The energy levels can be described as being in an s, p, d, or f orbitals. The number of protons in an atom being called the atomic number. The mass number is the same number of particles in the nucleus. Leucippus then had the thought that everything in the universe was made up of elements that could not be broken down. The term atomon was used to describe how atoms could not be