2. Review

What is an Ionic Bond?

The strong force of electrostatic attraction between oppositely charged ions.

DO NOT WRITE: "between a metal and non-metal" as a definition.

It takes a lot of energy to break an ionic bond, hence, ionic compounds have high melting points.

What is a Covalent Bond?

The strong force of attraction between a shared electron pair and the nuclei of the atoms in the bond.

The electron pair has a negative charge and the nuclei of the atoms are positively charged.

It takes a lot of energy to break a covalent bond, hence, giant covalent structures have high melting points.

NOTE - melting and boiling substances made from covalent MOLECULES does not involve breaking covalent bonds.

REMEMBER…

Ionic Bond            between a Metal and Non-Metal            (M + NM) Covalent Bond     between a Non-Metal and Non-Metal  (NM + NM)

PART 1: Determine if the elements in the following compounds are metals or non-metals. Describe the type of bonding that occurs in the compound.

Compound Element 1 (metal or non-metal?) Element 2 (metal or non-metal?) Bond Type
NO2 N = non-metal O = non-metal covalent
NaCl      
SO2      
PI3      
MgBr2      
CaO      
H2O      
K2O      
AlF3      
O2      
CuCl2      
NO2      
CO2      
HF      
Rb2S      
NBr3      
Fe2O3      
CCl4      

                        

PART 2: Use Lewis dot structures to show the ionic bonding in the following pairs of elements. Show the transfer of electrons using arrows. Write the correct chemical formula for the ionic compound that forms.

  1. barium oxide (Ba and O)
  2. sodium oxide (Na and O)
  3. calcium chloride (Ca and Cl)
  4. sodium nitride (Na and N)
  5. aluminum oxide (Al and O)
  6. magnesium phosphide (Mg and P)

PART 3: Use Lewis dot structures to show the covalent bonding in the following pairs of elements. Once you have determined the structure for the molecule, write its structural formula in the space provided; use a dash to represent a shared pair of electrons, and dots to show unshared electrons.

  1. nitrogen triiodide (NI3) HINT: nitrogen is in the middle!
  2. carbon tetrabromide (CBr4) HINT: carbon is in the middle!
  3. dihydrogen monoxide (H2O) HINT: oxygen is in the middle!

Covalent and ionic diagrams

Aim

To practise identifying and drawing covalent and ionic bonding.

 Instructions

Draw the atoms of each of the elements. Then, draw the dot and cross diagram for the molecule those elements could react to form. Work out which bond ionically and which bond covalently.

Carbon and hydrogen

Methane (CH4)

Potassium and bromine

Potassium bromide

Magnesium and chlorine 

Magnesium chloride

Sulfur and hydrogen

Hydrogen sulphide (H2S)  

Draw dot cross diagrams for the following substances:

  1. Hydrogen gas
  2. Chlorine gas
  3. Calcium sulfide
  4. Oxygen gas
  5. Nitrogen gas
  6. Hydrogen chloride
  7. Carbon dioxide
  8. Sodium oxide
  9. Ethane
  10. Ethene