atomic structure

• what is an element?

  a substance made from only one type of atom
• what is a compound?

  a substance made from 2 or more different types of atom bonded together
• what is a mixture?

  2 or more substances not bonded together
• what is a molecule?

  2 or more atoms bonded together in a small group
• name the three subatomic particles:

  • protons
  • neutrons
  • electrons
• describe the plum pudding model of the atom:

  electrons embedded in a cloud of positive charge
• what did the alpha scattering experiment prove?

  atoms have a small, dense nucleus which has a positive charge
• what is the atomic number of an atom?

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

  the total number of protons and neutrons in the nucleus
• what did james chadwick discover?

  neutrons
• describe the nuclear model of the atom:

  a small nucleus made from protons and neutrons with electrons orbiting the nucleus
• why do atoms have no charge?

  the number of protons = the number of electrons

  charges cancel out
• state the relative atomic masses and charges of the subatomic particles:

  • protons: RAM 1, charge +1
  • neutrons: RAM 1, charge 0
  • electrons: RAM very small, charge -1
• how many electrons can fit on the shells of an atom?

  1. 2
  2. 8
  3. 8