CHEM 1150 Lecture Notes - Lecture 2: Cathode Ray Tube, Chemical Change, Pauli Exclusion Principle
Document Summary
Atom= the basic structural unit of an element. Nucleus= small, dense, positively charged region in the center of the atom. Atomic number= the number of protons in the atom. Mass number= sum of the number of protons and neutrons. Number of neutrons= mass number - number of protons. Isotopes= atoms of the same element having different masses. Atomic mass= the weighted avg. of the masses all the isotopes that make up the element. 2. multiply the decimal fraction by the mass of the isotope to obtain the isotope contribution to the atomic mass. 3. sum these partial weights to get the weighted avg. atomic mass of element. Dalton"s atomic theory= the first experimentally based theory of atomic structure of the atom. True: all matter consists of tiny particles called atoms. False due to radioactivity: an atom cannot be created, divided, destroyed, or converted to any other type of atom.
