1. Bell Ringer 4-21-09 Period # tell you _____________________.
Group # tells you _____________________.
Draw an electron dot diagram for Br (Bromine).
What is the octet rule?
Show how these two atoms bond:
Ca + Se 

2. Bell Ringer 10-26-09 An ionic bond is a transfer of ________.
If an element gives up an electron, its charge is _______.
If an atom takes an electron, its charge is _______.
For an atom to be happy, it needs ______ electrons in its outer energy level (with the exception of He).
Draw an electron dot diagram for Si (Silicon).

3. ALCOS Objectives # 2 Describe the structure of atoms.
# 5 Differentiate between ionic and covalent bonds.

4. Covalent bonds
Chapter 5
Section 3

5. “Co” = together, or sharing
Covalent Bonds
“Co” = together, or sharing
A covalent bond involves a SHARING of electrons.

6. Recall that ionic bonds usually form between a metal and a nonmetal.
Covalent Bonds usually form between nonmetals.
Recall that ionic bonds usually form between a metal and a nonmetal.

7. Molecule
A molecule is a NEUTRAL group of atoms joined by covalent bonds.

8. Water
H O H

9. Double and Triple Bonds
Double bond- chemical bond formed when atoms share two electrons
O O O C O
Triple bond- chemical bond formed when atoms share three electrons
N N

10. Properties of covalent bonds
Low melting points
Low boiling points
Do NOT conduct electricity when dissolved in water

11. Covalent Bond

12. Two types of covalent molecules

13. Unequal Sharing of Electrons
In a covalent bond, atoms of some elements pull more strongly on shared electrons than do atoms of other elements.

14. Polar and Nonpolar covalent bonds
Polar- Unequal sharing of electrons
H F
Nonpolar – EQUAL sharing of electrons
F F