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 An ion is an element that has gained or lost electrons  Oxidation numbers are used to show the charge of an ion.  A positive ion is called a cation  A negative ion is called an anion

 Write the element symbol first  As a superscript, write the oxidation number  Ex. Ba 2+ or Ba +2

 Force that holds oppositely charged ions together is called an ionic bond  Between a metal and a nonmetal  Electrons are lost or gained  High melting and boiling points  Can dissolve in water to produce electrolytes (produces an electric current)  Example: NaCl

 Lowest ratio called a formula unit  First write the ions with their oxidation numbers  The charges on each elements switch and become the subscripts (tells the amount of that atom) on the other element  Take just the numbers, NOT THE CHARGES  Simplify  The metal goes first then write the nonmetal.  Examples: ◦ Na and Cl ◦ Mg and F ◦ K and P ◦ Be and O

◦ Na and Cl ◦ Mg and F ◦ K and P ◦ Be and O

 The cation is written as normal  The anion drops the last part of the element and add –ide  Example: Sodium + Chlorine = Sodium Chloride

 Ions made up of more than one element  Charge applies to the entire ion  Written in parenthesis in ionic formulas  Ex. Mg(OH) 2

Ion nameIon Formula AmmoniumNH 4 + NitriteNO 2 - NitrateNO 3 - HydroxideOH - CyanideCN - HypochloriteClO - ChloriteClO 2 - ChlorateClO 3 - PerchlorateClO 4 - CarbonateCO 3 2- SulfiteSO 3 2- SulfateSO 4 2- PhosphatePO 4 3-

 Sodium Phosphate  Calcium Chlorite  K 2 CO 3

 What is an ionic bond between?  Put the ionic bond together and name it: ◦ Mg and P  Show the Lewis diagram for the previous problem  What is a polyatomic ion?  Write the following ionic bond: ◦ Calcium Hydroxide

 Transition metals can have multiple charges  When writing the name, the charge of the transition metal must go in parenthesis using Roman numerals  Ag +1, Zn +2, Cd +2 only have one common charge  Ex. Iron (III) oxide ◦ Cu 3 P 2 ◦ MnO