 How are ionic compounds named?  What do the numerical prefixes used in naming covalent compounds tell you?  What does a compound´s empirical formula indicate?

Empirical formula Anion Molecular formula Cation

 The names of ionic compounds consist of the names of the ions that make up the compounds  Name of cations include the elements of which they are composed Ion name and symbol Cesium ion, Cs+ Lithium ion, Li+ Sodium ion, Na+ Barium ion, Ba2+ Calcium ion, Ca2+ Aluminum ion, Al3+ Ion charge1+2+3+

 Names of anions are altered names of elements  NaF: is made of sodium ions, Na+, and fluoride ions, F-. Therefore, its name is sodium fluoride  An ionic compound must have a total charge of zero  If an ionic compound is made up of ions that have different charges, the ratio will not be 1:1  For calcium fluoride to have a total charge of zero, there must be two fluoride ions for every calcium ion

 Some cation names must show their charge  The charge of the iron cation in Fe 2 O 3 is different from the charge of the iron cation in FeO. In cases such as this, the cation name must be followed by a Roman numeral in parentheses that shows the cation’s charge.  Fe 2 O 3 is made of Fe 3+ ions, so it is named iron (III) oxide. FeO is made of Fe 2+ ions, so it is named iron (II) oxide.

 Determine the charge of a transition metal cation  How can you tell that the iron ion in Fe 2 O 3 has a charge of 3+?  Write formulas for ionic compound using names  You can find the charge of each ion in a compound if you are given the compound’s formula. You can find the formula for a compound if you are given the compound’s name

 Math Skills: Writing Ionic Formulas  Go to go.hrw.com and enter keyword HK8MPgo.hrw.com

 For covalent compounds or two elements, numerical prefixes tell how many atoms of each element are in the molecule  Numerical prefixes are used to name covalent compounds of two elements  If there is only one atom of the first element, the name does not get a prefix  The element farther to the right in the periodic table is named second and ends in –ide  One boron atom and three fluorine atoms make up boron trifluoride, BF 3

 An empirical formula tells us the smallest whole-number ratio of atoms that are in a compound  Different compounds can have same empirical formula  Molecular formulas are determined from empirical formulas  Masses can be used to determine empirical formulas

 Empirical formula: the composition of a compound in terms of the relative number and kinds of atoms in the simplest ratio  Molecular formula: a chemical formula that shows the number and kinds of atoms in a molecule, but not the arrengement of atoms

 Math Skills: Finding Empirical Formulas  Go to go.hrw.com and enter keyword HK8MPgo.hrw.com