Naming Ionic Compounds

Charges Elements will gain or loose electrons to have 8 valence electrons. (This is the octet rule) How many valence electrons does Na have? If you lose that electron, what charge will you have? +1

Charges Group 1A  +1 Group 2A  +2 Group 3A  +3 Group 4A  +4 / -4 Group 5A  -3 Group 6A  -2 Group 7A  -1 Group 8A  STABLE The charges of monatomic ions, or ions containing only one atom, can be determined by referring to the periodic table

Ions An ion is an atom or group of atoms that has a charge A compound that is composed of ions is called an ionic compound. Ionic compounds usually form between a metal and a nonmetal. They may also form between a polyatomic ion (like ammonium) and either a metal or nonmetal. In ionic compounds, you will TRANSFER valence electrons

Ions A cation An anion A monatomic ion is one element with a charge positive ion formed when an atom loses electrons. Example: Na+ An anion negative ion is formed when an atom gains electrons Example: Cl- A monatomic ion is one element with a charge A polyatomic ion is more than one element with a charge Example: SO42-

Formation of Ionic Compounds Remember that objects with opposite charges attract each other. The strong attractive force between ions of opposite charge is called an ionic bond. Don’t forget that even though the ions have charges, the overall charge of the compound will be … ZERO!

Examples of Formula Writing Write the formula for the compound formed between sodium and chloride Na  Na +1 Cl  Cl -1 Na+1 Cl-1 (criss-cross charges & reduce) Na1Cl1 (What’s wrong here?) Do Not write the 1’s NaCl

More examples Write the formula between Mg and Br Mg  +2 Br  -1

More examples Write the formula for the compound formed between Ca and S Ca  Ca +2 S  S -2 Ca+2 S-2 CaS

Polyatomic Ions Polyatomic ions are groups of covalently bonded atoms that have a charge For example: SO4 -2 NO3 –1 ClO3 –1 NH4 +1

Polyatomic Ions When writing formulas, you must keep the polyatomic ions grouped together When you write a subscript next to a polyatomic ion you MUST put parentheses around the polyatomic ion first!

Formula writing with polyatomic Ions Write the formula for the compound formed between sodium and nitrate Na +1 NO3 -1 (bring down the charges) NaNO3

Formula writing with polyatomic Ions Write the formula between ammonium and sulfate NH4 +1 SO4 -2 (NH4)2 SO4

More examples Copper (II) and chlorine Silver and Nitrate Magnesium and sulfite Calcium and sulfur Potassium and oxygen Ammonium and phosphate Ammonium and chlorine CuCl2 AgNO3 MgSO3 CaS K2O (NH4)3PO4 NH4Cl

Don’t Forget! There are some elements that form multiple charges (the ones with the roman numerals) That roman numeral will tell you the charge! For example: Copper (II)  Cu +2

Multiple Charges to Remember Copper Iron Lead Tin Manganese Gold Cobalt +1 and +2 +2 and +3 +2 and +4 +2, +4, and +7 +1 and +3

Naming ionic compounds In naming ionic compounds, name the cation first, then the anion. Monatomic cations use the element name. Monatomic anions use the root of the element name plus the suffix -ide. (This means 1 element with a negative charge will end in –ide).

Naming ionic compounds If an element can have more than one charge, use a Roman numeral in parentheses after the element name, for example, iron(II) to indicate the Fe 2+ ion. For polyatomic ions, use the name of the ion.

Examples NaCl MgSO4 K3PO4 Ca(ClO3)2 NH4NO2 Al(ClO)3 CuSO3 Fe(NO3)2 Sodium chloride Magnesium sulfate Potassium phosphate Calcium chlorate Ammonium nitrite Aluminum hypochlorite Copper (II) sulfite Iron (II) nitrate

More examples Lead (IV) Oxide Ammonium Permanganate Cobalt (II) chloride Calcium sulfide Lithium nitrate Sodium acetate Tin (II) chloride PbO2 NH4MnO4 CoCl2 CaS LiNO3 NaCH3COO SnCl2