Humboldt State University ® Department of Chemistry

Richard A. Paselk

Chem 107

Fundamentals of Chemistry

Fall 2009

Lecture Notes: 10 September

© R. Paselk 2009
 
     
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Chemical Nomenclature

Recall the elements you must know, shown on the Periodic Table below:

Periodic Table of the Elements
 IA IIA IIIA IVA VA VIA VIIA VIIIA
1 2 13 14 15 16 17 18
   H  He
Li Be    B C N O F Ne
Na Mg 3 4 5 6 7 8 9 10 11 12  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        

Note the:

Compounds, Formula, Formulae (Formulas), and Molecules

You may find the table of elements on the Chemistry Department web site useful in organizing these elements into more memorable categories - but you only need to memorize those noted above.

Covalent vs. Ionic compounds:

  • In covalent compounds atoms have a definite relationship to each other, they are "married." Thus for water, H2O, the smallest particle is a water molecule containing one oxygen atom and two hydrogen atoms.
  • In ionic compounds ions of opposite charge attract each other, but there is no definite attachment, just a constant ratio. Thus in sodium chloride crystals each sodium ion is surrounded by six chloride ions and each chloride ion is surrounded by six sodium ions and they are equally attracted by each - there is no one-to-one relationship.

This distinction will be important in some aspects of naming chemical compounds.

IUPAC vs traditional names

There are two common naming systems:

The IUPAC/Stock system

This is the modern, systematic scheme developed by the International Union of Pure and Applied Chemists. Important nomenclature information is available on the Chemistry Department General Chemistry Supplement pages.

  • In this system the positively charged elements in a compound are named as the element name followed by the "apparent charge" (later we will see this really refers to something called the oxidation number which often = charge) written in Roman numerals enclosed in brackets. Thus iron two-plus = iron (II) and iron three-plus = iron (III). Elements which exhibit only one charge do not require that the charge be shown. Thus sodium one-plus = Na, magnesium two-plus = Mg and aluminum three-plus = Al. (Recall that the alkali metals are always plus one or zero and the alkaline earth metals are always plus two or zero.) Look at the Table of Ions for additional ions.
  • For negatively charged single atom ions the ending -ide is placed on the beginning of the element name. Thus chlorine one-minus becomes chloride, and similarly we see fluoride, bromide and iodide, while the two-minus charge ions of Group VIA become oxide, sulfide, etc.

Recognize these traditional names for metal ions:

      • Fe(II) = ferrous
      • Fe(III) = ferric
      • Cu(I) = cuprous
      • Cu(II) = cupric 
      • Hg(I) = mercurous {Hg22+)
      • Hg(II) = mercuric

Polyatomic ions

In these ions a group of atoms are covalently bound to each other and functions as a single charged particle. You should memorize the following:

Compounds

Salts (Ionic Compounds) and Bases

Ions of opposite charge may combine to form neutral compounds. Thus the ions must combine in ratios such that the charges cancel. When the negative ion is hydroxide, the compound is considered a base. Examples:


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Last modified 10 September 2009