atoms

• what is the atom made up of?

  • protons
  • neutrons
  • electrons
• what does the nucleus contain?

  protons + neutrons
• what charge does the nucleus have?

  positive
• describe electrons

  • move around the nucleus in shells (energy levels)
  • negatively charged
  • tiny
  • no mass
• describe protons

  • equals number of electrons
  • positively charged
  • mass is 1
  • found in nucleus
• what is an atomic number?

  it is the number of protons in an atom
• what is the mass number?

  it is the total number of protons and neutrons in the atom
• how do you find the number of neutrons?

  subtract the atomic number from the mass number
• what are molecules?

  groups of atoms
• what are isotopes?

  Isotopes are different atomic forms of the same element, which have the same number of protons but different numbers of neutrons
• what is the relative atomic mass?

  it is just a way of saying how heavy different atoms are compared with the mass of an atom
• what is the symbol for relative atomic mass?

  Ar
• T or F

  the relative atomic mass is this average mass of the isotopes in an element

  T
• what does relative abundance mean?

  how much there is of each isotope compared to the total amount of the element in the world
• what are elements?

  elements consist of one type of atom only
• what are compounds?

  is a substance that is made of two or more different elements which are chemically joined (bonded) together
• give an example of a compound

  carbon dioxide
• what are mixtures?

  a combination of two or more substances that are not chemically bonded.
• is a mixture pure + why?

  no, only substances made of a single element or compound are pure