Notes

Everything is made of matter.
Joseph Louis Proust proposed the Law of Definite Proportions.
In the early 1800's, English Philosopher John Dalton formulated Dalton's Atomic Theory.
All substances in nature are composed of tiny particles called atoms.
Greek philosopher Democritus was the first to propose the idea of atoms.
Atoms are made up of protons (+), neutrons (=), and electrons (-).
The plum pudding model of an atom had the protons everywhere like "bread" with electrons embedded like "plums".
The plum pudding model was disproved in 1909 by Ernest Rutherford.
Rutherford came up with the planetary model with a nucleus.

In nuclear fission, large atoms are hit with neutrons, they then fall apart into 2 smaller atoms with a few extra neutrons. The mass of the final product is lower than the mass of the initial atom and neutron. The extra mass is converted into energy. This disproves the Law of Mass Conservation. However, the law still holds true for chemical purposes.
Neutrons don't affect an atom's chemistry, but they do affect its mass. These variations in the amount of neutrons are called Isotopes. All naturally occurring elements have isotopes.

	Created by Rachel Osborne almost 9 years ago

High School Diploma Chemistry Note on Chapter 2: What's the Matter, created by Rachel Osborne on 30/12/2015.