atoms and subatomic particles

• define an atom

  the atom is the smallest part of an element that can exist
• define element

  a substance made up of only one type of atom
• define compound

  a substance formed when 2 or more elements are chemically bonded together
• define a mixture

  a substance when 2 or more elements are not chemically bonded together
• mass number


  how many neutrons and protons an element has
• atomic number


  how many protons an element has
• define isotopes

  isotopes are different forms of the same element they have the same number of protons and different number of neutrons
• electron

  -1
• neutron


  0
• proton


  +1
• group 7 as you go down the halogens get less reactive
• group 1

  noble gases aren't reactive
• group 1


  reactivity increases as you go down
• metal

  • strong
  • malleable
  • high boiling and melting points
• non metal

  • dull looking
  • don't conduct electricity or heat
  • aren't always solids
• atoms


  are neutral
• electrons

  no mass
• nucleus

  positive charge because of the protons