Bond Formation and Hybrid Orbitals Textbook Reference: pp.400 - 410

1. Bond Formation and Hybrid Orbitals Textbook Reference: pp.400 - 410

2. Meaning . . . ? Hybrid Orbitals We consider the energy of the s an p blocks to be close enough that rather than consider an s sub-shell and a p sub-shell, containing 2 and 6 electrons, respectively; we treat them all as the same energy level. This notion allows us to rationalize the ease with which carbon can form 4 bonds, nitrogen forms 3 bonds and a lone pair (or 4 bonds)

3. Formation of Hybrid Orbitals

4. Types of Hybrid Orbitals When we have an atom with 4 available spaces (a central atom with 4 atoms bonded to it) we need to use the s and all 3 p orbitals to form the hybrid orbitals which we designate sp3. If our central atom is 3 coordinate (therefore tigonal planar) we say its hybridization is sp2. If our central atom is in a a linear arrangement (2 coordinate) its hybridization is said to be sp.

5. Bond Formation and Type We know that atoms use their valence electrons to form covalent bonds. We also know that there can be multiple covalent bonds between two atoms (NO3-, C2H2). If we consider two covalent bonds will repel one another (e- - e- repulsion) how do we fit 3 bonds between the 2 carbon atoms in acetylene (aka ethyne aka C2H2)? There are two types of covalent bond: - s (sigma) bonds - p (pi) bonds Single bonds contain only a s bond; while double bonds contain a s and a p bond and a triple bond is made up of a s and two p bonds.

6. s bonds, p bonds . . . What the . . . ? To form a s bond a hybrid orbital (sp, sp2 or sp3) must interact with that of a terminal atom (group). A p bond is the result of the leftover or un-hybridized orbitals on the central atom. Consider H-C=C-H - both carbon’s are sp hybridized (1 s bond to H 1 s bond to the other C) - the two remaining p orbitals on each carbon are said to overlap and each form another covalent bond

7. Some more examples of hybrid orbitals