Ch. 9.1 Naming Ions Learning the language of Chemistry

Monoatomic Ions  A monoatomic ion consists of a single atom with a positive or negative charge resulting from the loss or gain of one or more valence electrons, respectively.

Cations  Metallic elements in groups 1A, 2A, and 3A tend to lose electrons and form cations with positive charges equal to their group number.  The names of these cations are the same as the name of the metal, followed by ion.  Na + is the sodium ion.  Ca 2+ is the calcium ion.

Anions  Nonmetals tend to gain electrons to form anions.  The charge of any Group A anion is determined by subtracting 8 from the group number.  Anion names start with the root of the element’s name, but end in –ide.  Most elements in Groups 4A and 8A do not form ions.

Ions of Transition Metals  Many elements from the transition metals form more than one cation with different ionic charges.  The charges of the cations of many transition metal ions must be determined from the number of electrons lost.  Example: Common ions of iron are Fe 2+ and Fe 3+.

 Stock system of naming…Fe 2+ is iron(II) ion. Fe 3+ is iron(III) ion.  Older naming system uses suffixes. Uses elements latin root with –ous for the lower ionic charge and –ic for the higher ionic charge…ferrous and ferric. See table on pg  Exceptions: transition metals silver, zinc and cadmium have only one ionic charge.

Polyatomic Ions  Composed of more than one atom that are tightly bound, have a net charge, and act together as a single ion.  Usually end in –ite or –ate (nitrite or nitrate)  -ite means one less oxygen atom in the polyatomic ion than –ate.  Memorize the polyatomic ions in table 9.3 on page 257.