Ionic Bonds
How Bonds Form
Electrons are transferred from a metal to a nonmetal.
Ex: NaCl, CaI2, Fe2O3
-metals form cations (+)
(gives away electrons)
-non-metals form anions (–)
(steals electrons)
Properties – Think SALT!!
• ALWAYS crystalline solid at room temperature
• VERY HIGH melting points and boiling points
• Hard and brittle
• Conduct electricity when melted or dissolved in water
(ions – aqueous solution)
• Usually very soluble in water (dissolves)
Lewis Dot Structures
Octet Rule: All atoms will form bonds in order to have
full (8) valence electrons.
1. Draw a separate Lewis Dot structure for each element.
2. Draw arrows to show transfer of electrons.
3. If needed, add more atoms for transferring.
Used 1 Na+1 ion and 1 Cl-1 ion, so formula is NaCl.
Ex. Na and Cl
Ex. Ca and F
Used 1 Ca+2 ion and 2 F-1 ions, so formula is CaF2.
Example:
Magnesium and Nitrogen
Naming
1. Write the name of the metal.
(LEAVE SPACE HERE!)
2. Change the ending of the nonmetal to –ide.
Ex 1. NaCl = Sodium chlorine
= Sodium chloride
Ex 2. Li2O = Lithium oxygen
= Lithium oxide
Ex 3. Mg3N2 = Magnesium nitrogen
= Magnesium nitride
Writing Chemical Formulas
1. Write the oxidation # (charge) of each ion above symbol.
2. If the charges cancel out, only 1 of each ion is needed.
3. If the charges for each atom do NOT cancel out, use the
criss cross method to determine subscripts.
4. Write the formula using ONLY symbols and subscripts.
Ex. Potassium phosphide
+1
K
K3P
P
-3
Writing Chemical Formulas (examples)
Ex 1. Calcium sulfide
+2
Ca
S
-2
CaS
Ex 2. Iron (IV) nitride
+4
Fe
N
-3
Fe3N4
Naming
1. Write the name of the metal.
• Use Roman numerals for transition metals to identify
the charge.
• Check the charge of the nonmetal to help determine
the transition metals charge.
2. Change the ending of the nonmetal to –ide.
Ex 4. Cr2S3 = Chromium sulfur
= Chromium III sulfide
Ex 5. CuO = Copper oxygen
= Copper II oxide
Ex 6. Cu2O = Copper oxygen
= Copper I oxide
Naming (with polyatomic ions)
1. Write the name of the metal.
• Use Roman numerals for transition metals to identify
the charge.
• Check the charge of the nonmetal to help determine
the transition metals charge.
• OR ammonium
2. Change the ending of the nonmetal to –ide.
• OR name of polyatomic ion (do not change ending!)
Naming (examples)
Ex 7. NH4Br =
ammonium bromide
potassium carbonate
Ex 8. K2CO3 =
Ex 9. Ca(NO3)2 =
+2
calcium nitrate
-3
Ex 10. Fe3(PO4)2 =
iron II phosphate
Writing Chemical Formulas (examples)
Ex 3. Sodium phosphate
+1
Na
(PO4)
-3
Na3PO4
Ex 4. Calcium nitrite
+2
Ca
(NO2)
-1
Ca(NO2)2