Chapter 7

 Indicate the number of atoms of each kind in a compound  For a molecular compound (covalent) it is the number of atoms but in an ionic compound it is the ratio of cation to anions

 Parenthesis are used around polyatomic ions (more than one atom)  A subscript after a parenthesis means everything inside is multiplied by the subscript  Subscripts tell the number of atoms in the molecule  Ex: Al 2 (SO 4 ) 3

 The positive and negative charges balance to form a zero net charge  Ex Na+ and Cl- balance to form a zero net charge when they are linked together

 Formed by a single atom  The charge is usually how many electrons it either gains or gives when it fill the valence shell (Main Group)  D block elements can have multiple ions  We us a roman numeral after them to tell which ion is being used  See chart on page 205  Ex: Copper (I) or Copper (II)

 Monatomic cations are their name ◦ Lithium = Li+ ◦ Calcium = Ca+  Monatomic anions is the root of the name then - ide ◦ Fluorine becomes fluoride

 Two different elements join together  The charges must be equal

1. Write the cation first with the charge as a superscript. Al Write the anion second with the charge as a superscript O Then cross them down Al 2 O 3

 The cation is the element name  The anion drops the ending and adds ide Al 2 O 3 Becomes Aluminum Oxide Now Practice

 Some ions have more than one charge (oxidation number)  Use Roman numerals to indicate which charge is being used ◦ Cu(II)Cl 2 ◦ Name of Cation+Name of Anion Roman Numeral Cu(II)Cl 2

 Oxyanions ◦ Anion containing oxygen ◦ Most common ones end in  -ate ex: Nitrate; Sulfate ◦ Ions with one less charge become  -ite ex: Nitrite ; sulfite  (NO 2 ) - Nitrate (NO 3 ) - Nitrite  Look them up!

 These are COVALENTLY bonded  New system is Stock Nomenclature  Old system uses prefixes on table 7.3 in your book. There will be a quiz on these  We will go to new system but the old system is still used frequently and is the basis for the names of chemicals.

 1. Less electronegative is first  2. First word gets the prefix for the number of atoms, except if the number is one.  3. The second combines ◦ A) the prefix for the number of atoms ◦ B) the root word part of the atom ◦ C) the suffix –ide  4. An (a) or (o) at the end of the prefix gets dropped

P 4 O 10 Tetraphosphrous Dioxide  NO nitrogen monoxide nitric oxide  NO 2 nitrogen dioxide  N 2 O dinitrogen monoxide laughing gas  N 2 O 4 dinitrogen tetraoxide  PCl 5 phosphorous pentachloride