describe the atom as a positively charged nucleus surrounded by negatively charged electrons, with the nuclear radius much smaller than that of the atom and with almost all of the mass in the nucleus

describe how and why the atomic model has changed over time to include the main ideas of Dalton, Thomson, Rutherford and Bohr

recall the typical size (order of magnitude) of atoms and small molecules

recall that atomic nuclei are composed of both protons and neutrons, and that the nucleus of each element has a characteristic positive charge

recall that nuclei of the same element can differ in nuclear mass by having different numbers of neutrons, these are called isotopes

use the conventional representation to show the differences between isotopes, including their identity, charge and mass

recall that some nuclei are unstable and may emit alpha particles, beta particles, or neutrons, and electromagnetic radiation as gamma rays

relate emissions of alpha particles, beta particles, or neutrons, and gamma rays to possible changes in the mass or the charge of the nucleus, or both

use names and symbols of common nuclei and particles to write balanced equations that represent the emission of alpha, beta, gamma, and neutron radiations during radioactive decay

explain the concept of half-life and how this is related to the random nature of radioactive decay

calculate the net decline, expressed as a ratio, in a radioactive emission after a given (integral) number of half-lives

interpret activity-time graphs to find the half-life of radioactive materials