atomic struc (1)

• atom


  Smallest piece of an element.
• nucleus


  The centre of an atom.
• electron


  A subatomic particle that orbits the nucleus.
• electron relative charge


  -1
• electron relative mass


  1/2000
• alpha particle


  A positively charged particle made up of two protons and two neutrons.
• nucleus contains


  Neutrons and protons.
• nuclear model


  A model of the atom that says that the atom has a small, central positively charged nucleus with negatively charged electrons moving around the nucleus.
• most of an atom is

  empty space
• proton


  A positively charged subatomic particle found in the nucleus.
• proton relative charge


  +1
• proton relative mass


  1
• neutron


  A neutral subatomic particle found in the nucleus.
• neutron relative charge


  0
• neutron relative mass


  1
• atomic number


  The number of protons in the nucleus of an atom.
• atomic mass


  The number of neutrons and protons in the nucleus of an atom.
• ion


  An atom in which the number of electrons is different to the number of protons, giving it an overall charge.
• radioactive decay


  The random process of a radioactive substance giving out radiation from the nuclei of its atoms.
• radioactive substance


  A substance that spontaneously emits radiation from the nuclei of its atoms.
• alpha decay


  A type of radioactive decay in which an alpha particle is emitted from a nucleus.
• beta decay


  A type of radioactive decay in which a beta particle is emitted from a nucleus.
• gamma decay


  A type of radioactive decay in which a gamma ray is emitted from a nucleus.
• beta particle


  A high speed electron.
• gamma ray


  A high frequency, short wavelength electromagnetic wave.
• Geiger-Muller tube


  A particle detector that is used with a counter to measure count-rate.
• half-life (nuclei)


  The time it takes for the number of nuclei in a radioactive isotope to half.
• half-life (activity)


  The time it takes for the count-rate or activity of a radioactive isotope to fall to half its initial level.
• activity


  The number of nuclei of a sample that decay per second.
• contaminated


  The presence of unwanted radioactive atoms on or inside an object.
• irradiated


  Exposure to radiation.
• most dangerous (contamination)


  Alpha radiation
• most dangerous (irradiation)


  Gamma radiation
• Beta particle


  A high speed electron emitted from the nucleus of an atom during certain types of radioactive decay
• Beta decay


  The decay of a neutron in the nucleus of an atom into a proton, an electron, and a neutrino. The electron and neutrino are both emitted from the nucleus at high speed, while the proton remains in the nucleus.
• Weak nuclear force


  One of the four fundamental forces of nature, responsible for governing beta decay and other types of radioactive decay
• Radioactive isotopes


  Atoms with an unstable nucleus that are prone to decay through various mechanisms, including beta decay