8: model of matter 2

• What is an atom

  atoms are the smallest unit of an element that have all properties of that element
• What are the three types of particles that atoms are made of


  Protons

  electrons

  neutrons
• The nucleus has a

  positive charge. Almost all the mass the mass of an atom is contained in the nucleus
• Why does an atom have no overall charge / electrically neutral

  Number of protons and neutrons are equal
• How to find number of protons 


  Top left corner
• How to find number of neutrons

  ( bottom left corner )mass number - atomic number ( top left corner )
• Define the term atomic number


  Atomic number of at atom is the number of protons in the atom
• Define the term nucleon/ mass number

  The nucleon (mass) number of an atom is the total number of protons and neutrons in the atom
• Diff elements have


  different numbers of protons in their atoms. This, they have diff physical and chemical properties
• Diatomic molecules

  molecules that are formed by the combination of two atoms
• Polyatomic molecules


  Molecules consists of four or more atoms that are chemically combined together
• Triatomic molecules


  Molecules that are formed by the combination of three atoms