Humboldt State University ® Department of Chemistry

Richard A. Paselk

Science 331
Fall 2004 Lecture/Activity Office: SA560a
Notes: 27 October Phone: x 5719
Home: 822-1116
e-mail: rap1

Chemical Periodicity, cont.

Terms:

You should know the terminology above and memorize the names and symbols for the elements shown in the table below.

 
Periodic Table of the Elements
 IA IIA IIIA IVA VA VIA VIIA VIIIA
   H  He
Li Be    B C N O F Ne
Na Mg IIIB IVB VB VI VIIB VIIIB IB IIB  Al Si P S Cl Ar
K Ca   Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
 Rb Sr                  Ag  Cd   Sn     I  Xe
 Cs  Ba        W        Pt Au  Hg    Pb        

 

Examples of Periodic Properties

Let's look at some of the elements and see what their properties are like:

2 Na + 2 H2O Æ 2 Na+ + 2 OH- + H2

2 Na + Cl2 Æ 2 NaCl

General Properties:

Trends: Note the trends for

  1. atomic size: decreases going from left -> right and from bottom -> top; overall have diagonal, Cs (largest) -> F (smallest).
    1. Size goes up with atomic number for any individual group.
    2. Size decreases irregularly as atomic number increases for any given period (more charge pulls electrons in to nucleus, but shielding reverses as subshells [s or p orbital sets] file.
  2. ionization energy: increases from left -> right and from bottom -> top; overall have diagonal, Cs (lowest) -> F (highest).
    1. Ionization energy goes down with atomic number for any individual group.
    2. Ionization energy increases irregularly as atomic number increases for any given period (more charge pulls electrons in to nucleus, but shielding reverses as subshells [s or p orbital sets] fill.
  3. Note metallic vs. non-metallic elements"
    1. Groups IA, IIA, all B groups, diagonal from Al - Po gives a divide between, with elements on line and next to line on right often semi-metallic.

 

 

Matter and Atoms

Why do we think atoms exist?


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© R A Paselk

Last modified 27 October 2004