Writing and Naming Ionic compounds (criss cross method)

Be Cl Rule 1: Write the symbol of the metallic element first. Beryllium combines with Chlorine + 2 - 1 Be Cl Rule 2: Place the combining capacity of one element as a subscript of the other element.

Be Cl2 1 The formula becomes BeCl2 Rule 3: Leave subscripts with a value of 1 out. Be Cl2 1 The formula becomes BeCl2

Rule 4: Reduce the subscripts when necessary by the greatest common factor. Magnesium combines with Sulfur + 2 - 2 Mg S S Mg Mg S

Potassium combines with chlorine Magnesium combines with bromine Calcium combines with oxygen Sodium combines with nitrogen Lithium combines with sulfur KCl MgBr2 CaO Na3N Li2S

Naming Ionic Compounds Two general rules: 1. Write the full name of the metal ion first. 2. Name the non-metal ion dropping the last part of the name and adding the suffix “ide”. The naming of compounds is monitored and updated by the International Union of Pure and Applied Chemistry (IUPAC).

Potassium combines with chlorine Magnesium combines with bromine Calcium combines with oxygen Sodium combines with nitrogen KCl - Potassium Chloride MgBr2 - Magnesium Bromide CaO - Calcium Oxide Na3N - Sodium Nitride

Total e- given by metals equals total e- taken by the non-metals The metal is named first and the non-metal is named second. The non-metal always changes end to an “ide”. Criss Cross Method - combining capacity of one is the subscript of the other. Reduce the numbers is possible (2, 4 = 1, 2) Total e- given by metals equals total e- taken by the non-metals

Transition metals can give away different numbers of electrons. To avoid confusion: Brackets are used to show how many electrons the Transition metal is giving away.

Roman numerals tell combining capacity of Transition metals. II 2 III 3 IV 4 V 5 VI 6 VII 7 VIII 8 IX 9 X 10

Fe Cl Fe Cl FeCl2 FeCl3 Iron (III) chloride Iron (II) chloride + 2 - 1

Write the formula for cobalt (III) oxide: + 3 - 2 Co O Co2O3

Co Br CoBr Cobalt Bromide (III) Write the name of this ionic compound: +3 - 1 Co Br CoBr 3 Cobalt Bromide (III)

Pb O PbO lead oxide (IV) Write the name of this ionic compound: +4 -2 1 Pb O PbO 2 lead oxide (IV)

CuS Cu S copper sulfide (II) Write the name of this ionic compound: +2 -2 + 1 - 1 Cu S CuS copper sulfide (II)

3. Lead (II) combines with sulfur Pb S +2 -2 Pb S lead (II) sulfide

Write the symbol of the metallic element first. WRITING COMPOUNDS: Write the symbol of the metallic element first. Place the combining capacity of one element as a subscript of the other element. Leave subscripts with a value of 1 out. NAMING COMPOUNDS: Write the full name of the metal ion first. Name the non-metal ion dropping the last part of the name and adding the suffix “ide”. Brackets are used to show how many electrons the Transition metal is giving away.