Transcript Covalent bonds - Mrs. Haynie's 8th Grade Physical Science

Bell Ringer
1.
2.
3.
4.
5.
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 
Bell Ringer
10-26-09
1. An ionic bond is a transfer of ________.
2. If an element gives up an electron, its charge is
_______.
3. If an atom takes an electron, its charge is _______.
4. For an atom to be happy, it needs ______ electrons in
its outer energy level (with the exception of He).
5. Draw an electron dot diagram for Si (Silicon).
ALCOS Objectives
# 2 Describe the structure of atoms.
# 5 Differentiate between ionic and covalent
bonds.
Covalent bonds
Chapter 5
Section 3
Covalent Bonds
“Co” = together, or sharing
A covalent bond involves a SHARING of
electrons.
Covalent Bonds usually form between nonmetals.
Recall that ionic bonds usually form between a
metal and a nonmetal.
Molecule
A molecule is a NEUTRAL group of atoms joined by
covalent bonds.
Water
H
O
H
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
Properties of covalent bonds
Low melting points
Low boiling points
Do NOT conduct electricity when dissolved in water
Covalent Bond
Two types of covalent molecules
Covalent Molecules
Polar molecules
Nonpolar molecules
Unequal Sharing of Electrons
In a covalent bond, atoms of some elements pull
more strongly on shared electrons than do atoms of
other elements.
Polar and Nonpolar covalent bonds
Polar- Unequal sharing of electrons
H F
Nonpolar – EQUAL sharing of electrons
F
F