Covalent Bonding

Ionic bond - a metal bonded to a non-metal, electrons are transferred

Covalent bond - a non-metal bonded to another non-metal, electrons are shared, remember molecules try to arrange themselves into octets using each others valence electrons

Molecule - formed when two or more atoms are bonded covalently

Diatomic Molecules - H2, N2, O2, F2, Cl2, Br2, and I2 form a 7 on the periodic table. These elements only exist as pairs in nature. They are more stable

ex. F2 - has seven valence electrons and must have one more to be "happy"

As 2 F atoms approach each other they both have a negative charge so they repel each other, as they move even closer the attraction of the nuclei for the other atoms electrons becomes large enough to over power the repelling forces

Single Bonds - when a single pair of electrons are shared

ex. H2

Lewis structures - use electron-dot diagrams to show how the bonds are formed

ex. H20each H atom attains noble gas configuration of He by sharing

electrons with O, and O attains noble gas configuration of Ne by sharing electrons with 2 H's

Sigma Bond - single covalent bonds· occurs when the electron pair is shared in an area centered

between the two atoms· when the valence atomic orbital of one atom overlaps with the

valence atomic orbital of the other atom· used to identify where the electrons will most likely be found

Multiple Bonds - many molecules form double, or triple bonds to gain noble gas configuration

ex. O2 N2

Pi Bonds - · formed when parallel orbitals overlap to share electrons· the shared electron pair of a pi bond occupy the space above and below the line that represents where the two atoms are joined together· Consists of one sigma bond and at least one pi bond

Strength of a Covalent Bond

·Remember that the bond has both attractive and repulsive forces so it can be broken easier than an ionic bond·Covalent bonds strength depends on how much distance separates the nuclei·Double and Triple bonds are stronger than single bonds because the atoms are closer together·Energy is released when a bond is formed and energy must be added when a bond is broken·Bond Dissociation energy - the energy required to break a covalent bond (always a positive value)

Indicates the strength of a chemical bond·Endothermic reactions occur when a greater amount of energy is required to break the existing bonds then is released when the new bonds form·Exothermic reactions occur when more energy is released forming new bonds than is required to break bonds in the initial reactants

Molecular and Acid Naming

Ch 6 Lecture Notes 07-08.notebook

Molecular Structures - uses letters and lines to show bonds

Coordinate Covalent Bond- Forms when one atom supplies both electrons to a shared pair- Occurs in many polyatomic ions- Example: NH3 & H3B

Properties of Covalent Compounds- Made of molecules- Have lower melting points

Resonance- When two or more structures can be written for a molecule- The actual structure is a blend of the structures- Example: NO3-

Hybridization- Two or more orbitals (of nearly equal energy) combine into orbitals of equal energy- Hybridized orbitals orient themselves as far apart from one another as possible - Helps to explain the shape of molecules - VSEPR Theory (Gold Sheet)

- Valence Shell Electron Pair - ex. C has 4 valence e- [He] 2s2 2p2

Bond PolarityNonpolar Covalent Bonds- Bonding electrons are shared equally- Electronegativity difference of 0.4 or less- Example:

Polar Covalent Bonds- Bonding electrons are shared unequally- Electronegativity difference of 0.4 - 2.0- The more electronegative atom has a slight negative (δ-) charge- The less electronegative atom has a slight positive (δ+) charge- Example: H2O

Molecular Polarity- Depends on bond polarity and shape of molecule- If bonds are nonpolar, then molecule is nonpolar

- Example:

- If bonds are polar but molecule is symmetrical, then molecule is nonpolar

- Example: CH4

- If bonds are polar and molecule is not symmetrical, then molecule is polar- Called a “dipole”

- Example:

WS examples: Use your Gold Sheet!!!!!!!

SiCl4 - Bond Skeleton Hybrid Type3-D structure

TEST!!!!!

10 Molecular Naming 10 Acid Naming3 True False5 MC

Vocab - structural formula sigma bondmolecule polar covalentVSEPR model pi bondcoordinate covalent covalent bondhybridization resonanceoxyacid endothermicelectronegativityexothermic

3 Drawings