Chapter 9- Covalent Bonds Agenda- Lab - Review - Quiz – Review –Chapter 8 / 9 Test – Chapter 8/9

Section 1  Why do atoms bond?  To become noble or stable  To achieve an octet (are exceptions) Covalent Bonds

What is a covalent Bond?  Elements share electrons  Majority form between nonmetallic elements Result?  A Molecule is formed Covalent Bonds

Lewis Dot Review: In your notes draw the following dot structures and determine the number of bonds for each  H  N  O  C  S  Cl  Ar

Groups and Bonds  Group 15 = 3 Bonds PH 3  Group 16 = 2 Bonds H 2 S  Group 14 = 4 Bonds  CCl 4  Group 17 = 1 Bond HCl Lewis structures

Lewis Dot Structures It’s a Puzzle…  Use the dot structures to make all atoms octet.  Remember… H only has 2 dots and is never a central atom Example: HCL  Draw the dots and put them together

Example: H 2 S Lewis Dot Structures Draw the dots and put them together

Sigma Bond  The single covalent bond is calls the… “Sigma Bond”  Shared electrons between two atoms

Multiple Covalent Bonds Why Multiple Bonds? Hint: Think Noble.  To achieve an Octet! Example: C 2 H 4  Draw the central atoms  Attach the surrounding atoms  Make sure each atom has an octet

Sigma and pi Bonds Sigma Bonds  Two atoms share electrons pi Bonds  Parallel orbitals over lap  Forms double bonds Example: C 2 H 4

Let’s take a closer look

Lets take a closer look

Strength and Energy Bond Strength  The shorter the bond length, the stronger the bond, the greater the bond-dissociation energy Bond Energy  Endothermic – more energy is needed to break the bond than is released  Exothermic – more energy is released during bond formation than is required to break it.