Atomic Models and Isotopes

Describe an atom as having negatively charged electrons around a positively charged nucleus, which holds almost all of the atom's mass and has a radius much smaller than that of the atom.
Describe how and why the atomic model has changed over time, including the main ideas of Dalton, Thomson, Rutherford, and Bohr.
Recall the order of magnitude of the typical size of an atom and of a small molecule.
Recall that an atomic nucleus is made up of protons and neutrons, and that each element's nucleus carries its own characteristic positive charge.
Recall that isotopes are nuclei of one element that differ in nuclear mass because they have different numbers of neutrons.
Show how isotopes differ in identity, charge and mass using the conventional representation.

What you need to know