Grade 9 Physical Science
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Worksheet for Section 20.2: Chemical Bonding.
General Information:
1- Atoms can achieve a noble gas structure by gaining, losing or sharing electrons
with other atoms.
2- The rule states that, except for hydrogen , an atom combines with other atoms to form
bonds in order to have 8 electrons in its valence energy level ( like noble gases).
Lewis dot symbols are representations of the elements which give a dot ( . ) for each
valence electron on the atom.
The Lewis dot symbols for the period 2 elements are:
Be
Li
B
C
N
O
F
Ne
1. Fill in the Lewis dot symbols for:
Ga
P
Br
Ca
Si
Lewis dot structures allow us to understand two types of
bonding, Ionic and Covalent.
Ionic Bonds
Ionic bonds are usually formed by the reaction of metals with non-metals.
Example: Fill in the Lewis dot symbols for Na and Cl, below, and complete the
shorthand electron configuration for each:
Na
Cl
Now allow each atom to complete its Valence energy level with 8 electrons, by losing or
gaining electrons. Then write the Lewis structure for each ion and its charge.
Na
Cl
Sodium loses an e-because it’s a metal
Chlorine gains an e- because it’s non-metals.
2. 4.
Use Lewis dot symbols to show the transfer of electrons between the following
atoms to form ions:
a)
K and S
b)
O and Ba
c)
Ca and F
d)
Al and Cl
e) Mg and O
Covalent Bonds
These are bonds formed between non-metals.
So octets of valence electrons are obtained by sharing electrons, instead of gaining or
losing electrons.
An example of covalent bonding is F2, fluorine gas.
3. Complete the Lewis dot symbols for the fluorine atoms below
F
F
4. Use the Lewis diagram/structure to show how H and O react to form water, H2O.
5. Draw the Lewis diagram/structure to show how N and H react to form Ammonia, NH3.
6. Draw the Lewis structure of Nitrogen, N2.
7. Draw the Lewis structure of Oxygen, O2.
8. Draw the Lewis structure of Hydrogen, H2.
9. Draw the Lewis structure of Hydrogen chloride, HCl
10. Label (ionic) or (covalent) the bonds in the following compounds.
CO2
Na2O
SF2
N2O
CaO
Na2CO3 (careful)
11. Fill the following table to compare between Ionic and Covalent bond
Criteria
How does it form
Ionic Bond
Electron transfer
Covalent bond
Type of reacted elements
Nonmetal with non metal
Name of resulting
compound
Molecule
12. Which is more stable Cl or Cl- Ion? Why?
13. Assign the following as: Ionic, Polar covalent or nonpolar covalent :
a) C-Cl
b)N-F
c) C-F
d) H-Cl
e) Mg-O
f) C-O
g) O-O
h) Si-O
i) N-O