1. Chapter 8 Chemistry 1L Cypress Creek High School
Unit 8: Ionic Bonds
Chapter 8
Chemistry 1L
Cypress Creek High School

2. Part 1: Introducing Ionic Bonds

4. Chemical Bonds
A bond is a force that holds atoms together; creates a compound with new properties which differ from the individual elements
Chemical bonds form because of attractions between oppositely charged atoms, called ions
Octet Rule
Atoms bond because they are trying to achieve stable electron configurations like the noble gases (8 valence electrons)

5. Ionic Bonds
Table salt, represented by the formula NaCl, is an example of a compound formed by an ionic bond +  Na Cl
NaCl
Element
Metal or Nonmetal?
Number of valence electrons?
Oxidation number?
Sodium
Chlorine
Metal
Nonmetal

6. Common Ionic Compounds
Sodium bicarbonate (NaHCO3) is baking soda used in food, cleaning products, and antacids
Sodium chloride (NaCl)
is table salt used in food
Potassium nitrate (KNO3) is saltpeter used in fertilizer, gunpowder, and food preservatives
Sodium hydroxide (NaOH) is lye used in soaps and drain cleaner

7. Common Ionic Compounds
Magnesium sulfate (MgSO4) is epsom salt used medically as a soak for aches & pains
Potassium bromide (KBr) is used to prevent epilepsy (seizures) in dogs
Sodium fluoride (NaF) is an ingredient in toothpaste used for cavity prevention
Calcium carbonate (CaCO3) is found in rocks (limestone and marble), shells, chalk; primary cause of hard water

8. Ionic Compound Properties
Also known as salts
A single entity is called a formula unit
Exist as solids at room temperature
Easily dissolve in water
Exhibit a crystal structure

9. Ionic Compound Properties
Possess high melting / boiling points
Considered an electrolyte – a compound that conducts electricity in solution (dissolved in water)
Have high electronegativity differences between ions

10. Ionic Bonding & Electronegativity
Ionic bonds are composed of cations and anions bonded together
Atoms actually bond according to the difference in their electronegativity (ability to attract valence electrons)
Look at table of EN values and find the difference between the two atoms involved (absolute value)
Subscripts do not affect this calculation
If EN difference is > 1.7 = ionic bond
>1.7

11. Ionic Bonding & Electronegativity

12. Ionic Bonding & Electronegativity
Try to predict the bond type (ionic or not ionic) using your EN table:
Formula
EN values
EN Difference
Bond Type
LiCl
Li = 1.0
Cl = 3.0
2.0
ionic
CO2
MgO
B3P2
NF3
C = 2.5
O = 3.5
1.0
not ionic
Mg = 1.2
O = 3.5
2.3
ionic
B = 2.0
P = 2.1
0.1
not ionic
N = 3.0
F = 4.0
1.0
not ionic

13. Formation of Ionic Bonds
Ionic bonds occur when valence electrons are transferred from one atom to another – usually between a metal and a nonmetal
Cations donate/give/lose electrons
Anions accept/take/gain electrons
Opposite charges make them attracted (bonded) to each other by electrostatic forces

14. Formation of Ionic Bonds
What is the charge of…
A sodium ion? ____
A chlorine ion? ____
NaCl? ____
The overall charge of any ionically bonded compound is zero - this means stability! 1+ 1-