Periodic Table Notes

I.  Developing the Periodic Table
    A.  Dobereiner & Newlands
         1.  Dobereiner
              a.  found that properties of the metals calcium, barium, and strontium were similar
              b.  grouped these 3 elements into a triad
              c.  later, grouped other elements into triads
         2.  John Newlands
              a.   arranged elements in order of increasing atomic mass
              b.  law of octaves -- described his arrangement because the same properties repeated
                   every eight elements

    B.  Mendeleev
          1.  Properties of elements were a function of their atomic masses.  This was called the
              periodic law.
          2.  In 1860's, he made an eight - column table of elements, but he left some blank spots
               so that all the elements with similar properties could be grouped in the same column.
          3.  Predicted the properties and atomic masses of several elements that were unknown at
               that time
          4.  Today, the missing elements have been discovered, and Mendeleev's predictions have
               been found to be very nearly correct.
          5.  In his table, elements were arranged in order of increasing atomic mass.
          6.  Because properties of elements repeated in an orderly way, it was called periodic.

   C.  Modern Periodic Law
          1.  Henry Mosley made an exception to Mendeleev's periodic law.
          2.  Modern Periodic Law says that the properties of the elements are a periodic function of
               their atomic number.

   D.  Modern Periodic Table
         1.  Reflects electron configurations of atoms
         2.  Transition Elements
               a.  electrons are added to the d sublevel
               b.  position on the periodic table reflects overlap of energy levels
         3.  Lanthanoids & Actinoids
              a.  lanthanoids:  electrons are added to 4f sublevel
              b.  actinoids:  electrons are filling the 5f sublevel
         4.  Period - elements in a horizontal row
         5.  Group - elements in a vertical column

II.  Using the Periodic Table
     A.  Electron Configurations
          -- can use periodic table to find most correct electron configurations

     B.  Relative Stability
          1.  Only s & p electrons can be in the outer level of atoms
          2.  octet rule :  8 electrons in outer level make an atom unreactive
          3.  noble gases :  8 electrons in outer level; most chemically stable; helium is stable with
               2 outer electrons
          4.  filled or 1/2 filled sublevels are more stable (less reactive) than those that are not
               filled or 1/2 filled
          5.  least stable to greatest stability
                no arrangement, 1/2 full sublevel, full sublevel, full outer level

     C.  Metals and Nonmetals
          1.  Family - another name for group
                Group 1 :  Alkali Metals
                Group 2 :  Alkaline Earth Metals
                Group 3 - 12:  Transition Metals
                Group 16 :  Chalcogens
                Group 17 :  Halogens
                Group 18 :  Noble Gases

           2.  Metals
                a.  hard & shiny
                b.  conduct heat & electricity
                c.  contain only a few outer electrons
                d.  tend to lose outer electrons when forming compounds
                e.  elements with 3 or fewer outer electrons (general rule)
                f.  located on the left side of the periodic table

          3.  Nonmetals
                 a.  generally gases or brittle solids @ room temperature
                 b.  solid - dull surface
                 c.  insulators; they don't conduct electricity well
                 d.  have more electrons in outer level
                 e.  gain electrons or share electrons when forming compounds
                 f.  5 or more outer electrons (general rule)

           4.  Metalloids
                 a.  have properties of metals and nonmetals
                 b.  elements considered to be metalloids:
                       boron    silicon    germanium    arsenic    antimony    tellurium
                       polonium              astatine