Pre-Ap Chemistry: The Discovery Of The Atum

Jack’Quoia Baulding
Mrs. Allen
Pre-Ap Chemistry
8 February 2018
The Discovery of the Atom Look at all that is around us, it is matter. The matter is anything that has a mass and takes up space. Theories of matter were first discussed by ancient Greek philosophers around 400 B.C. Many scientific theories and discoveries were major in the discovery of the atom. Democritus is credited to have been the one to predict atoms and John Dalton proved it. In the discovery of atoms, the subatomic particles were found and their charges also, the radioactivity and how the radioactivity of atoms is measured.
Democritus was an ancient Greek philosopher. He came to the conclusion that matter was composed of elementary particles called atoms. An atom is the

Dalton used Democritus's word, atom to describe these very tiny particles. The atomic theory is attributed to Dalton, and was the first attempt to describe all matter in terms of atoms and atomic properties; this theory was based off of the law of conservation of mass. The law of conservation of mass states that matter is not created or destroyed, meaning in a chemical reaction the amount of space is the same from the start to finish. This theory held that matter includes atoms and that all elements are alike. He said that atoms of one element are different from atoms of other elements. An element is a substance made up of one atom. Dalton said that all matter is made up of atoms and that all atoms of a given element are identical in mass and properties. He proposed that compounds are combinations of two or more different types of atoms and in a chemical reaction ions are

The protons, neutrons, and electrons make up the subatomic particles. The scientist that is responsible for discovering protons is Ernest Rutherford. He did an experiment with a beam of alpha particles and a very thin sheet of gold. He found that the heavy particles were deflected backwards revealed what the positive charge of an atom was, and almost all of the atom’s mass is concentrated in the center of the atom. The positive charge of the atom is known as the protons. Rutherford also discovered the nucleolus, which is at the center of protons and neutrons. The nucleolus is tiny and has a positive charge. Neutrons, one of the other subatomic particles was demonstrated by Chadwick. He also found that neutrons have no charge.The number of neutrons in the nucleus of an element determines the isotope. An isotope is two or more different forms to write an element and an isotope has its own form, or symbol that it is written in. J. J Thomson discovered the electron and that they have a negative charge. Since electrons have a negative charge they attract to positive charges, protons. Thomson puts a high voltage to two electrodes sealed inside an evacuated tube, and an invisible ray emanates from the negative cathode. Another important discovery of the electron was done by Robert Millikan. Millikan did an Oil Drop Experiment and he determined the size of the charge of an