Chapter 9 Naming Ions

Naming Ions The metals in groups1A, 2A, and 3A lose electrons they form cations with positive charges equal to their group number. Ex. Na+ Ca+2 and Al+3 The names of the cations of Groups 1A, Group 2A, and Group 3A are the same as the name of the metal followed by the word ion or cation. Ex. Na+ =sodium ion Ca+2 = Calcium cation    Non- metals tend to gain electrons to form anions, so the charge is negative.   Anion names start with the root of the element name and end in -ide Ex. O-2 = oxide ion S2- = sulfide anion

Naming Ions The Charges of the cations of many transition metal ions must be determined from the number of electrons lost. Ex. Transition metal iron form two common cations Fe2+ and Fe3+ losing 2 and 3 electrons respectively.   Stock system of naming ions- A roman numeral in parentheses is placed after the name of the element to indicate the numerical value of the charge. Ex. Iron(II) ion = Fe2+ Iron(III) ion = Fe3+ Classical naming of ions uses Latin names with different suffixes to indicate the charge. Ferrous ion = Fe2+ Ferric ion = Fe3+

Naming Ions The names of most polyatomic anions end in -ite or -ate. The -ite ending usually has less oxygen atoms than polyatomic anions with the -ate ending.   Absolutely need to learn tables 9.2 pg 255 and table 9.3 pg 257

Naming and Writing Formulas for Ionic Compounds Binary compound- is composed of two elements and can be either ionic or molecular.   To name any binary ionic compound, place the cation name first, followed by the anion name. Ex.Cs+ O-2 = cesium oxide NaBr= sodium bromide Write the symbol of the cation and then the anion. Add whatever subscripts are needed to balance the charges. Ex. Fe 3+ O-2 Fe2O3

Compounds with Polyatomic Ions -ate or -ite ending on the name of a compound indicates that the compound contains a polyatomic anion that includes oxygen. CaCO3 - This compound contains a monoatomic cation and one polyatomic anion What are they? Ca+2 C03-2 Write the symbol for the cation followed by the formula for the anion and make sure to balance the forces. Ex. Ca(N03)2

Compounds with Polyatomic Ions Make sure to use parenthesis when the formula contains more than one unit of the same polyatomic ion. To name a compound containing a polyatomic ion, state the cation first and then the anion just as you do in naming binary ionic compounds.

Naming and Writing Formulas for Molecular Compounds molecule- is a neutral group of atoms(non-metals) joined together by covalent bonds. Binary molecular compounds are composed of two elements, but both elements are nonmetals and they are not ions.

Naming and Writing Formulas for Molecular Compounds The prefixes in the name of a binary molecular compound tell how many atoms of each element are present in each molecule of a compound. 1= mono- 6= hexa- 2= di- 7= hepta- 3= tri- 8= octa- 4= tetra- 9= nona- 5= penta- 10= deca-

Naming binary molecular compounds Confirm that a compound is composed of two elements. Identify the elements in the molecule. Identify the number of each atom of each element Name the elements in the order listed in the formula using prefixes to indicate the number of each kind of element. The suffix name of the second element is –ide.

Questions Name CL2 O8 Dichlorine octoxide Use the prefixes in the name to tell you the subscript of each element in the formula. Then write the correct symbols for the two elements with the appropriate subscripts. Ex. Dinitrogen tetroxide

Naming and Writing Formulas for Acids and Bases Acid- is a compound that contains one or more hydrogen atoms and produces hydrogen ions (H+)   When naming an acid, consider the acid to consist of an anion combined with as many hydrogen ions as are needed to make the molecule electrically neutral. Chemical formulas of acids are in general form HnX H= Hydrogen n = number of hydrogen ions X= is a monatomic or polyatomic anion This formula indicates the number of hydrogen ions that are combined with the anion.

Three Rules for Naming Acids When the name of the anion (X) ends in –ide. The acid name begins with the prefix hydro-. Add the suffix –ic to the anion and add the word acid. Ex. H2 S (aq) (X=sulfide) Hydrosulfuric acid When the anion name ends in –ite . The acid name is the stem of the anion with the suffix –ous followed by the word acid. Ex. H2 SO3 (aq) (X= sulfite) Sulfurous acid   When the anion name ends in –ate. The acid name is the stem of the anion with the suffix -ic followed by the word acid. Ex. HNO3 (aq) (X=nitrate) Nitric acid Use the rules for writing the names of acids in reverse to write the formulas for acids

Bases Base-is an ionic compound that produces hydroxide ions when dissolved in water. Bases are named in the same way as other ionic compounds-the name of the cation is followed by the name of the anion. Write the name of the metal cation, followed by the formula for the hydroxide ion. Balance the ionic charges. Ex. AL(OH)3 Aluminum hydroxide