Elements + compounds

• Atom


  Smallest part of an element
• Element


  A pure substance made of only one kind of atom

  
• Compound


  A substance made up of atoms of two or more different elements joined by chemical bonds

  
• Mixture


  A combination of two or more different substances that are not joined by chemical bonds

  
• Chemical symbol


  A one or two letter representation of an element

  
• Number of elements


  118

  
• Chemical reaction


  the formation of a new chemical substance

  
• Periodic table


  A chart of the elements showing the repeating pattern of their properties

  
• Property


  A description of a substance (e.g. soft/dense/shiny/reactive)

  
• Molecule


  A group of atoms bonded together (can be the same type of atom, or different types of atom).
• Separation of compounds


  Requires a chemical reaction to break the bonds between atoms.
• Formula of an element

  Has a single capital letter (e.g. O or Na)
• Formula of a compound

  Has more than one capital letter, and tells you the ratio of the elements in a compound. (e.g. CaO has a 1:1 ratio of calcium to oxygen)