UNIT 5 - THE PERIODIC LAW

History of the Periodic Table

I.  Mendeleev and Chemical Periodicity
    A.  Wanted to organize elements according to their ____________________
    B.  When elements were arranged in order of increasing atomic mass*, similarities in chemical
         properties appeared at regular intervals (____________________)
    C.  *Several elements did not quite fit this pattern - Mendeleev put elements with similar
         ____________________ in the same column or group
    D.  1871 - Mendeleev predicted the existence and properties of several (then undiscovered)
         elements.  These elements were:
    E.  Within 15 years, those elements with those properties had been discovered

II.  Moseley and the Periodic Law
    A.  When elements were arranged in order of increasing ___________________________________,
         there was a distinct regular pattern.
    B.  ____________________:  The physical and chemical properties of the elements are periodic
        functions of their atomic numbers.
    C.  In other words, when elements are arranged in order of increasing atomic number, elements
         with similar properties appear at regular intervals.
    D.  Bottom line = elements in the same group have similar properties

III.  Modern Periodic Table:  arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same group

Electron Configuration and the Periodic Table

I.  Stability of Noble Gases
    A.  Noble gases undergo very few chemical reactions - why?
    B.  Highest occupied energy level contains ________________________________________
    C.  Electrons in the highest occupied energy level are what determines an element's _____________

II.  Periods and Blocks of the Periodic Table
    A.
  Horizontal row = ____________________;  7 on modern Periodic Table
    B.  Length of period determined by the sublevels being filled in that period
    C.
  Period 1:  only _____ sublevel being filled;  can hold a maximum of _____ electrons; 
         period contains _____ elements
    D.  Period 4:  ____, ____, and ____ sublevels being filled;  s can hold ___ electrons, d can hold ___
         electrons, & p can hold ___ electrons; total of _____ electrons;
         Period 4 contains _____ elements
    E.  Period can be determined from the element's electron configuration
        1.  Bromine:  [Ar] 4s2 3d10 4p5
        2.  Highest number in front of letter is the element's highest occupied _____________________ -
             tells which period the element is in
        3.  For bromine, _____ is highest number, so it is in Period _____

 

 

III.  The "s" block elements:  Groups 1 and 2
    A.  Group 1 - Alkali Metals
        1.  generalized outermost energy level (valence) electron configuration:
        2.  silvery appearance
        3.  soft enough to cut with a knife
        4.  not found in nature as free elements - they're always part of a compound
        5.  with increasing atomic number, melting point ______________________
    B.  Group 2 - Alkaline Earth Metals
        1.  generalized valence electron configuration:
        2.  harder, stronger, more dense than Group 1
        3.  also have higher melting points than Group 1
        4.  less reactive than Group 1, but still not found in nature as free elements
    C.  Exceptions:  Hydrogen and Helium
        1.  Hydrogen (H)
            a.
  electron configuration:
            b.  properties do not resemble those of any other element on the periodic table
        2.  Helium (He)
            a.
  electron configuration:
            b.  in Group 18 because

IV.  The "d" block elements: Groups 3 - 12
    A.  called
    B.  have typical metallic properties:  ductile, malleable, shiny, solid, conduct electricity
    C.  less reactive than "s" block elements
    D.  found in nature as free elements
    E.  usual ending of electron configuration:

V.  The "p" block elements:  Groups 13 - 18
    A.  "s" and "p" block elements together referred to as _____________________________ elements
    B.  ending electron configurations of __________________ through ___________________
    C.  properties vary greatly b/c there are metals, metalloids, and nonmetals
    D.  Group 17 - Halogens
        1.
  most reactive nonmetals
        2.  seven electrons in outermost energy level
    E.  "p" block metals are harder and more dense than "s" block , but not as hard or dense as the "d"
         block metals

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