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: Al2(SO4)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

Na2S sodium sulfide Mg +2 and Cl -1

MgCl2 Magnesium Chloride

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

Mg3P2 Magnesium phosphide

Polyatomic ions

Are covalently bonded ions that have a charge and are used in ionic bonds.

Perchlorate ClO4 -

Chlorate ClO3 -

Chlorite ClO2 -

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: Na2SO3

NH4CN

K2SO4

Sodium sulfiteAmmonium 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 C2H3O2 -1

Ca(C2H3O2)2

Aluminum Chromate: Al+3 CrO3 -1

Al(CrO3)3

Ammonium sulfite: NH4+1 SO3 -2

(NH4)2SO3

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 Cu2O