1. Ionic and Covalent Bonds Chemistry Ms. Piela
The Chemical Bond
Ionic and Covalent Bonds
Chemistry
Ms. Piela

2. Ionic Compounds Overview
Bonds formed between a metal and a nonmetal
Metals form positive ions called cations
Trick to remember: “ca+ion”
Non-metals form negative ions called anions
Ionic bonds are formed by a transfer of electrons

3. Properties of Ionic Compounds
Ionic compounds dissociate (or break apart) in liquids
Example: Table salt in water
Ionic compounds can conduct electricity
If something conducts electricity, then ions/charges must be able to move
Solid ionic compounds are rigid, not allowing charges to move
Two conditions allow ionic compounds to conduct electricity:
Molten (or liquid)
Dissolved in solution
Example: Li-ion batteries

4. Properties of Ionic Compounds
Ionic compounds tend to have high melting points
This is due to the high strength of the ionic bonds
Stronger bonds need more energy to break apart!

5. Formation of Ionic Compounds
Ionic bonds follow the Octet Rule
Octet rule – Each element tends to form compounds based on the easiest way to gain 8 valence electrons
Example: Na and Cl
Sometimes combinations are not an easy one-to-one ratio!
Example: Ca and Cl

6. Formation of Ionic Compounds
Examples
Mg and O
K and S
Practice
Ba and N
Li and P

7. Formation of Ionic Compounds
Transition metal ionic compounds
All form positive ions (cations), but can form multiple ions
Example: FeCl2 and FeCl3

8. Covalent Compounds Overview
Covalent bonds are made between nonmetals only
Does NOT depend on charges!!
Covalent bonds will share electrons as both elements need to gain electrons to obtain full outer shell (8 valence electrons)

9. Properties of Covalent Compounds
Forms longer bonds because bonds are weaker than ionic bonds
Energy is lowered when atoms form a covalent bond
This is the main driving force behind their formation
There is a balance between their attractive and repulsive forces

10. Two Types of Covalent Bonds
Polar covalent bonds are covalent bonds where electrons are shared unequally between the atoms
Non-polar covalent bonds are covalent bonds where electrons are shared equally between the atoms

11. Polarity Polarity depends on differences in electronegativity
The greater the difference in electronegativity, the more polar the bond is
Example: Cl2 and HF
The more polar the bond, the stronger the bond
Polar covalent bonds have stronger bonds than non-polar bonds
Stronger bonds give higher boiling points (just like ionic compounds)

12. The Chemical Bond Overview
Nonpolar Covalent
Polar Covalent
Ionic
In order of increasing bond strength:
In order of increasing bond length:
Ionic
Polar Covalent
Nonpolar Covalent

13. Naming Ionic Compounds
Simple Naming Rules
Identify the compound as Ionic (Metal and a non-metal)
Determine charges for each ion
Overall charge of compound must be zero
General formula for names:
Cation + Anion Root-ide

14. Examples Calcium fluoride Calcium phosphide Magnesium nitride
Potassium oxide

15. Examples
LiCl2
SrBr2
BaI2

16. Transition Metal Compounds
Since transition metals form multiple ions, roman numerals denote charge
Roman numerals are not the number of molecules!

17. Examples iron (III) chloride copper (II) oxide iron (III) oxide
silver (I) sulfide

18. Polyatomic Ion Compounds
Some elements are considered as a charged group of two or more atoms. They are considered as a single ion called a polyatomic ion.
You will not need to memorize these, only recognize it when you see them

19. Examples Aluminum chromate Potassium hydroxide Sodium thiosulfate
Calcium acetate