general chemistry

• matter 


  anything that occupies space and has mass
• element


  a substance that cannot be separated into a simpler substance by chemical means
• 99% of human body made of

  carbon (backbone of organic compounds), hydrogen (component of organic compounds), oxygen (cellular respiration), nitrogen (component of proteins, nucleic acids, cell membranes)
• atom


  smallest unit of an element, made of electrons, protons, neutrons, smallest part of an atom that can undergo a chemical reaction
• size of an atom

  0.2 nanometres
• proton 


  +1
• neutron 


  0
• electron 


  -1
• atomic number (Z) 


  the number of protons in the nucleus of that element
• neutrons


  mass number - atomic number
• isotopes


  atoms of an element that have the same number of protons but different numbers of neutrons
• unstable isotopes


  break down and emit radiation
• technecium-99


  used to obtain images of the liver, heart and lungs
• iodine-131


  measures radioactivity just above the thyroid to see if iodine is absorbed at a normal rate
• iodine-125


  images the thyroid gland
• sodium-24


  used to detect blockages in the circulatory system
• helium-3


  mri of lungs
• somatic radiation damage


  affects organism during its lifetime e.g. sunburn
• genetic radiation damage 


  inherited from a parent who had radiation damage