Ionic Bonds

What is an ion? An atom that gains or loses electrons is an ion. A cation loses electrons and becomes a positive ion An anion gains electrons and becomes a negative ion

Octet rule Atoms want 8 electrons. This makes them stable and happy

Some atoms will give up electrons and some will gain to get to 8.

Oxidation numbers

Ionic Bonds A metal bonded to a nonmetal Give up and take electrons Ions held together by electrostatic force Conduct electricity in water because they break up into their ions High Boiling Point

Ionic bonds in solution

Lewis dot structure Use only the valence electrons Put a dot around the symbol of the element for each valence electron.

The metal will give up its electrons and the nonmetal will gain electrons

Naming ionic bonds Name the first element the same name as the metal. Name the second element and end in – ide Example: KCl Potassium Chloride If contain a polyatomic ion use the polyatomic ions name Example: Al 2 (SO 4 ) 3 Aluminum Sulfate

Writing binary ionic bonds The charge on an ionic bond must be zero So Na +1 and Cl -1 balance out to be zero and are written NaCl sodium chloride Mg +2 and S -2 balance out to be zero MgS Magnesium sulfide

When they do not balance out to zero you need more of one ion or the other. Na +1 and S -2 Na 2 S sodium sulfide Mg +2 and Cl -1 MgCl 2 Magnesium Chloride

Sometimes you need more of both. Mg +2 P -3 Mg 3 P 2 Magnesium phosphide

Polyatomic ions Are covalently bonded ions that have a charge and are used in ionic bonds. Perchlorate ClO 4 - Chlorate ClO 3 - Chlorite ClO 2 - Hypochlorite ClO -

Naming ternary ionic compounds Ternary ionic compounds have more than 2 types of elements Name the first element (or polyatomic ion) then name the second element (or polyatomic ion) Example: Na 2 SO 3 NH 4 CN K 2 SO 4 Sodium sulfite Ammonium cyanide Potassium sulfate

Writing formulas for ternary ionic compounds The charge on a compound must always be zero When there are more than one polyatomic ion it must be put into parentheses. ( )

Examples Calcium acetate: Ca +2 C 2 H 3 O 2 -1 Ca(C 2 H 3 O 2 ) 2 Aluminum Chromate: Al +3 CrO 3 -1 Al(CrO 3 ) 3 Ammonium sulfite: NH 4 +1 SO 3 -2 (NH 4 ) 2 SO 3

Metals with multiple charges Many metals have more than one oxidation number Then a roman number is used after the name of the metal Examples Copper (II) Oxide CuO Copper (I) Oxide Cu 2 O