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Home , Pi bond, Sigma bond

Chapter 8: Section 3 Bonding Theories

Covalent Bond­ Sharing by overlapping of the outer level orbitals

H

Orbital­ space occupied by 2 electrons in an ATOM

H2 H Atom H Atom

F Atom F Atom F2 Molecule

Sigma Bonds

1 Bonds:

When two share 2 electrons, the result is a . H­H Cl­Cl H­O­H

Sigma bonds σ All single bonds are sigma bonds Made by: an s orbital overlapping another s orbital s­p overlap p­p end­to­end overlap

2 When two atoms share 4 electrons, the result is a . O2 CO2

When two atoms share 6 electrons, the result is a . N2

Pi bonds π: Found in multiple bonds p­p parallel overlap

Double bond = 1 σ and 1 π

Triple bond = 1 σ and 2 π

C2H2

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C Atom C Atom C=C

Pi Bond Double Bond= 1σ and 1π

Sigma Bond

Triple Bond 1σ & 2π

4 Single bond- 1 sigma One shared pair of electrons

Double bond-1 sigma and 1 pi Two shared pairs of electrons

Triple bond- 1 sigma and 2 pi Three shared pairs of electrons

http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/bom5s2_6.swf

5 VSEPR: Valence Shell Pair Repulsion Model used to predict the shape of a molecule, based on the repulsion of shared and unshared pairs of electrons around the central atom of a molecule. Molecular orbitals Shared pair­ Two electrons shared between nuclei of 2 atoms Unshared pair­ Two electrons held by nucleus of only 1 atom This is a larger area, has more repulsive power

6 OK...so I'm sure you've wondering HOW can make FOUR bonds and sulfur can make SIX??? And the Noble gases????

7 Hybridization Allows for more bond sites to form. Orbitals from different sublevels combine and share electrons to create more bond sites.

C 1s22s22p2 2s 2p

2 3 Hybridized C 1s 2sp 4 orbitals available 3 2sp for bonding

Can Nitrogen hybridize? Oxygen? 1s22s22p3 1s22s22p4 N=O=N???

Only elements in the 3rd period, and beyond; the ones that have a d sublevel available can hybridize. Carbon

8 Examples: What are the shapes, bond angles, and hybridizations of the following ? Use the flow chart and instructions above to figure it out. 1) carbon tetrabromide 2) phosphorus trichloride 3) oxygen 4) the chlorine atom in hydrochloric acid (HCl) 5) boron trichloride 6) CH2O 7) sulfur difluoride 8) either carbon atom in C2H2

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