1. Section 3 – Covalent Bonds Pg 192
Chapter 5
Section 3 – Covalent Bonds
Pg 192

2. How Covalent Bonds Form
Pg 193
How Covalent Bonds Form
Covalent Bond: the chemical bond formed when two atoms share electrons
Usually between nonmetals

3. Pg 193
Electron Sharing
The force that holds atoms together in a covalent bond is the attraction of each atom’s nucleus for the shared pair of electrons
Molecule: a neutral group of atoms joined by covalent bonds

4. How many Bonds? Like in Water -> Pg 193
The # of covalence bonds that a nonmetal atom can form equals the number of electrons needed to make a total of 8
Oxygen has 6 valence electrons -> needs 2 so can form 2 covalence bonds
Like in Water ->
Pg 193

5. Double Bond and Triple Bond
Double Bond: two atoms share two pairs of electrons
Triple Bonds: atoms share three pairs of electrons
Pg 194

6. Molecular Compounds Pg 194
Molecular Compound: a compound that is composed of molecules
Contains atoms that are covalently bonded
Compared to ionic compounds, molecular compounds generally have lower melting points and boiling points
Also do not conduct electric current when melted or dissolved in water

7. Low melting point and boiling point
Pg 194
Low melting point and boiling point
The forces between molecules are much weaker than the forces between ions in an ionic solid
Takes less energy to break apart

8. Poor Conductivity Molecular compounds do not conduct electric current
Pg 195
Poor Conductivity
Molecular compounds do not conduct electric current
No charged particles are available to move (all locked up in bonds)
Used to insulate wires
Even as liquid, does not conduct electric current
Pure water does not conduct electric current

9. Unequal Sharing of Electrons
Pg 195
Unequal Sharing of Electrons
Atoms of some elements pull more strongly on shared electrons than other elements
Unequal sharing of electrons causes the bonded atoms to have a slight electrical charge

10. Polar Bonds and Nonpolar Bonds
Polar Bond: a covalent bond in which electrons are shared unequally
Nonpolar Bond: a covalent bond in which electrons are shared equally
Pg 196

11. Polar Bonds in Molecules
Pg 196
Polar Bonds in Molecules
A molecule is considered polar if it has a positively charged end opposite a negatively charged end
Carbon Dioxide is nonpolar because of its linear shape

12. Attractions Among Molecules
Pg 196
Attractions Among Molecules
The properties of polar and nonpolar compounds differ because of differences in attractions between molecules
Properties like viscosity!

13. Chapter 5 Section 3 Homework – pg 197

14. 1A. What is the attraction that holds two covalently bonded atoms together?

15. 1B. A carbon atom can form four covalent bonds
1B. A carbon atom can form four covalent bonds. How many valence electrons does it have?

16. 1C. What is a double bond?

17. 2A. How are the properties of molecular compounds different from those of ionic compounds?

18. 2B. Why are most molecular compounds poor conductors?

19. 3A. How do some atoms in covalent bonds become slightly negative or slightly positive? What type of covalent bonds do these atoms have?

20. 3B. Both carbon dioxide molecules and water molecules have polar bonds
3B. Both carbon dioxide molecules and water molecules have polar bonds. Why then is carbon dioxide a nonpolar molecule while water is polar molecule?

21. 3C. Predict whether carbon dioxide or water would have a higher boiling point.