HELIUM ATOM + N N + - - proton electron neutron Shell What do these particles consist of?
ATOMIC STRUCTURE Particle proton neutron electron Charge + ve charge -ve charge No charge 1 1 nil Mass
ATOMIC STRUCTURE the number of protons in an atom the number of protons and neutrons in an atom He 2 4 Atomic mass Atomic number number of electrons = number of protons
ATOMIC STRUCTURE Electrons are arranged in Energy Levels or Shells around the nucleus of an atom. first shella maximum of 2 electrons second shella maximum of 8 electrons third shella maximum of 8 electrons
ATOMIC STRUCTURE Three ways to represent the atomic structure of an element or compound; 1.Lewis Notation 2.Rutherford-Bohr Model 3.The Ball and Stick Model
Determine the number of shells and the number of valence electrons for:
Helium is the exception in Group 8. Since it has just one shell, that shell can only fit 2 electrons instead of 8. It is in this group because all the elements have a full outer shell.
Lewis Electron Dot Diagrams Invented by the American chemist, G.N. Lewis. 1.Write the chemical symbol 2.Write the appropriate number of dots in a clockwise manner
Lewis Structures 1)Write the element symbol. 2)Carbon is in the 4 th group, so it has 4 valence electrons. 3)Starting at the right, draw 4 electrons, or dots, counter- clockwise around the element symbol.
Lewis Structures 1)Check your work. 2)Using your periodic table, check that Carbon is in the 4 th group. 3)You should have 4 total electrons, or dots, drawn in for Carbon.
BOHR-RUTHERFORD DIAGRAMS Bohr-Rutherford diagrams should be drawn using the following steps: Draw the nucleus with the proper number of protons (+1) and neutrons (0). Draw the first electron shell with the appropriate number of electrons (-1).
BOHR-RUTHERFORD DIAGRAMS Draw the second valence shell (if applicable) with the appropriate number of electrons (-1). Continue to draw valence shells with electrons until you have the proper number of electrons for the element.