3.1 Atomic Theory and Atomic Structure
|MODERN ATOMIC THEORY
|1. All matter is composed of atoms.
|2. The atoms of an element are identical but different than atoms of other elements.
|3. The atoms of one element cannot be converted to another element by chemical reactions.
|4. Compounds are formed when atoms of different elements combine in whole number ratios.
Atomic Structure - An atom is comprised of a nucleus at its center that is composed of protons and neutrons surrounded by an electron cloud.
|ATOMIC THEORY SCIENTISTS
|Proposed his atomic theory
|Determined the charge of an electron (oil drop experiment)
|Discovered the nucleus (scattering of alpha particles in thin gold foil)
|Atomic Number – Equals the number of protons
|Mass Number – Equals the sum of the number of protons plus neutrons
|Charge – Equals the number of protons minus the number of electrons
|Isotopes – Forms of elements that have different mass numbers due to differing numbers of neutrons
Atomic Weight (a.k.a. Atomic Mass)
What is the atomic mass (also called atomic weight) of chlorine?