Ionic & Covalent

COVALENT IONIC

A covalent bond is formed between two non-metals that have similar electronegativities.

An ionic bond is formed between a metal and a non-metal. Non-metals(-ve ion) are "stronger" than the metal(+ve ion) and can get electrons very easily from the metal.

Occurs between: Two non-metals

Occurs between: One metal and one non-metal

Examples: Methane (CH4), Hydro Chloric acid (HCl)

Sodium chloride (NaCl),

Polyatomic IonsWriting Formulas / Naming Compounds

• A polyatomic ion is a covalent molecule that has an ionic charge. (As opposed to being a neutral molecule.)

• Poly = many• Atomic = atoms• Ion = charged particle• A charged particle that consists of more

than one atom.

Polyatomic Ions

Examples:

Sulfate = SO4-2

Nitrate = NO3-1

Phosphate = PO4-3

Chlorate = ClO3-1

Carbonate CO3-2

• Notice the ending has changed to –ate.

Writing Formulas

Sodium Sulfate• Write the formula for the metal. Add the

oxidation number from the periodic table.Na+1

• Write the formula for the polyatomic ion from the ion chart. Add its oxidation number.

SO4-2

Sodium SulfateNa +1 SO4

-2

• Determine the common factor of the two oxidation numbers. In this case, 2.

• Decide how many of each ion is needed to equal the common factor. In this case, 2 sodium ions and 1 sulfate ion.

• Write these numbers as the subscript for each ion.

Na2SO4

Calcium Phosphate

• Write the formula for the metal. Add the oxidation number from the periodic table.

Ca+2

• Write the formula for the polyatomic ion from the ion chart. Add its oxidation number.

PO4-3

Calcium PhosphateCa +2 PO4 -3

• Determine the common factor of the two oxidation numbers. In this case, 6.

• Decide how many of each ion is needed to equal the common factor. In this case, 3 calcium ions and 2 phosphate ions.

• Write these numbers as the subscript for each ion.

Ca3(PO4)2

• Notice that the polyatomic ion must be placed in parenthesis or, instead of 2 phosphate ions, you would have 42 Oxygen atoms and 1 Phosphorus atom.

Ca3PO42

Naming Compoundsw/ Polyatomic Ions

KClO3

• Write the name of the metal.Potassium

• Write the name of the polyatomic ion from the ion chart.

Chlorate• Name the compound.

Potassium Chlorate

Mg3(SO4)2

• Name the metal.

Magnesium

• Name the polyatomic ion from the ion chart.

Sulfate

• Name the compound.

Magnesium Sulfate

Some Additional Examples

• Calcium HydroxideCa+2 OH-1

• The least common factor is 2. Therefore, 1 calcium ion will bond with 2 hydroxide ions to form a neutral compound.

Ca(OH)2

• If you omitted the parenthesis, you would not have 2 hydroxide ions. Instead you would have 2 hydrogen atoms and one oxygen atom. CaOH2

Try these

• Write names for the following compounds. CaCO3

Al2(SO4)3

Ca(ClO3)2

K3PO4

Mg(OH)2

Answers

• Calcium carbonate

• Aluminum sulfate

• Calcium chlorate

• Potassium phosphate

• Magnesium hydroxide

Now, these!

• Write formulas for the following compounds. Lithium sulfate Aluminum nitrate Magnesium phosphate Sodium carbonate

Answers

• Li2SO4

• Al(NO3)3

• Mg3(PO4)2

• Na2CO3