1. Hybridization Section 14.2

2. Introduction A hybrid results from combining 2 of the same type of object and it has characteristics of both Atomic orbitals undergo hybridization during bonding Consider the methane molecule, CH 4 The electron configuration of C is 1s 2 2s 2 2p 2 You might expect the two unpaired p electrons to bond with other atoms and the 2s electrons to remain as a lone pair

3. Recall the orbitals, their shapes and how they are filled…

4. Carbon Hybridization This does not happen as we know carbon forms 4 bonds Hybridization: a process in which atomic orbitals are mixed to form new, identical hybrid orbitals Each hybrid orbital contains one electron that it can share with another atom

5. Carbon One s and three p orbitals hybridize to form four sp 3 orbitals

6. Shape According to VSEPR, a tetrahedral shape minimizes repulsion between the orbitals sp 3 orbitals

7. Another Hybrid Consider BF 3 There are three total pairs of electrons with three shared pairs VSEPR predicts a trigonal planar shape To have this shape, one s and two p orbitals on the B must mix to form 3 identical sp 2 hybrid orbitals Note that one p orbital is unoccupied

9. Another Hybrid Consider BeF 2 Electron configuration of Be is 1s 2 2s 2 Be must promote one electron to the 2p orbital Results in sp hybridization and a linear shape

10. More Information Lone pairs can occupy hybrid orbitals Consider water: It forms sp 3 hybrid orbitals and the two lone pairs on the oxygen atom are in two of the hybrid orbitals Look at the total number of negative centers on the central atom to discover the type of hybrid orbital 4 centers: sp 3, 3 centers: sp 2, 2 centers: sp

11. Organic Molecules Consider ethane (C 2 H 6 ), ethene (C 2 H 4 ) and ethyne (C 2 H 2 ) Decide which type of hybridization each carbon has Look on the board for drawings of these structures Ethane: sp 3, ethene: sp 2, ethyne:sp

12. Sigma Bond ( σ ) Sigma bond: occurs when the electron pair is shared in an area centered between the two atoms The atomic orbitals (could be hybrids) overlap end to end Electron density is at its greatest on the inter- nuclear axis (an imaginary line joining the two nuclei Single bonds are sigma bonds

13. Sigma bonds form first (single bonds) when atomic orbitals overlap end to end

14. Pi Bond ( π ) Pi bond: is formed when parallel orbitals overlap to share electrons High electron density is found above and below the inter-nuclear axis (not on it) A double bond consists of one sigma bond and one pi bond A triple bond consists of one sigma bond and two pi bonds

15. Pi bonds form after sigma bonds, so in a sense have to wrap around the outer ends, so can only do so side by side