Chemistry IGCSE-Ionic Bonding

1. © 2004-05 Dorje Gurung
Core Bonding: Ionic
Bonding

2. Core Bonding: Ionic Bonding Slide 2 of 20
Learning objective
Concepts:
– Ionic bond, ionic compound, electron transfer, ion, positive ion, negative
ion, ionic lattice, crystalline solid,
Skills:
Core
– Be able to identify atoms that usually form ionic bonds.
– Be able to use your knowledge of electron arrangement to represent ionic
bonding, using diagrams.
– Be able to work out the formulae of ionic compounds using your
knowledge of ionic bonding

3. Core Bonding: Ionic Bonding Slide 3 of 20
Which type of atoms react to form ionic bonds?
When atoms of metal elements react with non-metal atoms they tend
to form ionic bonds, the compounds they produce are therefore
referred to as ionic compounds.
Why do atoms react?
Metal atoms usually have one or two electrons in their outer energy
levels, these electrons are easily lost, this leaves an ion with full
energy shells which makes them a lot more stable.
Non-metal atoms tend to have 5, 6 or 7 electrons in their outer energy
levels.
– They can fill the energy level by capturing the electrons which metal
atoms want to give away.
– By filling their energy levels in this way these non-metals also form
more stable ions.

4. Core Bonding: Ionic Bonding Slide 4 of 20
Loss & Gain of Electrons
Protons: 3+ 9+
Electrons: 3- 9-
Electronic
configuration: 2, 1 2, 7
outer shell NOT full outer shell NOT full
energetically unstable energetically unstable
A lithium atom has 1 valence
electrons in its outer shell.
A fluorine atom has 7 valence
electrons in its outer shell.

5. Core Bonding: Ionic Bonding Slide 5 of 20
What types of ions are formed?
• The lithium atom has lost an
electron
• No longer a lithium atom now
• Instead a lithium ion, a positive
ion, which we write Li
+
• The fluorine atom has gained an
electron
• No longer a fluorine atom now
• Instead a fluorine ion, a negative
ion, which we write F

+
-

6. Core Bonding: Ionic Bonding Slide 6 of 20
Ionic Bond
Protons: 3+ 9+
Electrons: 2- 10-
Net charge: +1 -1
Elect. config.: 2 2, 8
outer shell full outer shell full
energetically stable energetically stable
Attraction
between positive
and negative ions
+
Postive ion
Also referred
to as a
(cat)ion
Negative ion
Also referred
to as a
(an)ion
-

7. Core Bonding: Ionic Bonding Slide 7 of 20
Ionic Bond
Both ions have filled their outer shell & become energetically stable by
the metal atom losing its valent electron & the non-metal atom
gaining it.
This transfer of an electron causes both atoms to become ions with
opposite electrical charges, which causes them to attract and bond.
IONIC BOND
An electric charge pull attraction between oppositely charged ions.
The compound formed is LiF.

8. Core Bonding: Ionic Bonding Slide 8 of 20
Ionic Bonding: Summary
Ionic bonds form between metals and non-metals
– Metal atoms lose electrons to form positive ions
– Non-metal atoms gain electrons to form negative ions
– The resulting bond is due to the attraction between the oppositely
charged ions, hence called ionic bonds
The next few slides show other examples of ionic bond formation
between metals and nonmetals and the resulting ionic compounds.

9. Core Bonding: Ionic Bonding Slide 9 of 20
Sodium and Chlorine
Na Cl
Protons: 11+ 17+
Electrons: 11- 17-
Net charge: 0 0
Elect. config.: 2, 8, 1 2, 8, 7
outer shell NOT full outer shell NOT full
energetically UNstable energetically UNstable
11+ 17+

10. Core Bonding: Ionic Bonding Slide 10 of 20
Sodium and Chlorine
Protons: 11+ 17+
Electrons: 10- 18-
Net charge: 1+ 1-
Elect. config.: 2, 8 2, 8, 8
outer shell full outer shell full
energetically stable energetically stable
Na+
Cl-
11+ 17+
+ 
Formula: NaCl

11. Core Bonding: Ionic Bonding Slide 11 of 20
Dot and cross diagram of NaCl
Notice, just as with atoms in molecules, only the valence shell is shown.
In the case of the positive ion, the valence shell is the next shell in.
Na+
Cl-
+ 
XX
XX
X
X
X
X
X

12. Core Bonding: Ionic Bonding Slide 12 of 20
Magnesium and Oxygen
12+ 8+
Mg O
12+ 8+
12+ and 10- = 2+
Mg2+
8+ and 10- = 2-
O2-
2+ 2 -
Formula: MgO

13. Core Bonding: Ionic Bonding Slide 13 of 20
Magnesium and Chlorine
Cl Cl
Mg
17+ 12+ 17+
12+ and 10- = 2+
Mg2+
12+
2+
-
17+ and 18- = 1-
Cl-
17+
17+ and 18- = 1-
Cl-
17+
-
Formula: MgCl2

14. Core Bonding: Ionic Bonding Slide 14 of 20
Sodium & Oxygen
Formula: Na2O
11+ 8+
Na O
11+
Na
11+
Na+
+
8+
O2-
2-
11+
Na+
+

15. Core Bonding: Ionic Bonding Slide 15 of 20
Dot and Cross diagram practice
Draw dot and cross diagrams for MgO, MgCl2 and Na2O.
(For more on the formula Extension Stoichiometry: Formula of
Compounds.)

16. Core Bonding: Ionic Bonding Slide 16 of 20
Ionic Lattice
What does a crystal of table salt l
k like?
Ionic compounds have a:
GIANT IONIC LATTICE
STRUCTURE
They are also referred to as
crystalline ionic lattice or
crystalline solids.
chloride (-) ion
sodium (+) ion

17. Ionic Bond Physical Properties
1. High melting point dan boiling point
2. Conduct electricity in molten or aqueous state
3. Dissolve in water
Core Bonding: Ionic Bonding Slide 17 of 20

18. Core Bonding: Ionic Bonding Slide 18 of 20
Breaking an ionic bond
HEAT (thermal)
ENERGY
+

19. Core Bonding: Ionic Bonding Slide 19 of 20
Breaking an ionic bond
+
Thermal (heat) energy is
absorbed (taken in) by the
ions.
Thermal energy is transferred to
kinetic (movement) energy - so the
electrons and nucleuses start
vibrating in all directions.

20. Core Bonding: Ionic Bonding Slide 20 of 20
Breaking an ionic bond
+
the distance between the ions
increases – resulting in the attractive
pull between them becoming weaker.
More thermal energy is transferred
to kinetic energy – causing the
electrons and nucleuses to vibrate
further distances in all directions.

21. Core Bonding: Ionic Bonding Slide 21 of 20
Breaking an ionic bond
MORE thermal energy is transferred to MORE kinetic energy – eventually
the two ions vibrate even further away from each other.
At this certain distance the attractive electric charge pull between the +
metal ion and - non-metal ion does not exist and the ionic bond
“breaks” – no actual “physical breaking” takes place – just moving
apart.
+

22. Core Bonding: Ionic Bonding Slide 22 of 20