2.2_orbitals_post

2.2_orbitals_post - VSEPR(Valence Shell Electron-Pair...

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2.2 Orbitals 1 VSEPR (Valence Shell Electron-Pair Repulsion) Helps predict the spatial arrangement of atoms in polyatomic molecules or ions. But it does not tell us anything about what is happening to the orbitals. C H H H H Tetrahedral N H H H O H H Trigonal pyramidal Bent 109.5 ° 107 ° 105 ° CC H H H H B F F F Trigonal planar 120° CN H H H CO H H Be H H HH H H Linear 180° +
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2.2 Orbitals 2 Linear C C R R C N R C O R + HC Ξ CH HC Ξ N HC Ξ O + VSEPR Covalent bonds are formed by overlapping of atomic orbitals, each of which contains one electron of opposite spin. Each of the bonded atoms maintains its own atomic orbitals, but the electron pair in the overlapping orbitals is shared by both atoms. The greater the amount of orbital overlap, the stronger the bond. Valence Bond Theory Cl Cl
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2.2 Orbitals 3 Describe the bonding and the orbitals of BeCl 2 Electronic configuration of Be is 1s 2 2s 2 Electronic configuration of Cl is 1s 2 2s 2 2p 6 3s 2 3p 5 Filled outer shell how can this bond? VSEPR : Each set of valence shell electrons on the central atom are arranged so that the repulsion is as small as possible. Be BeCl 2 should be linear – this is what we observe experimentally 1s 2 2s 2 2p Could promote one electron Filled outer shell how can this bond? But this would produce dissimilar orbitals with non equivalent overlap between the s orbital of Be and the p orbital of chlorine and the p of Be and p of chlorine. Experimentally it is found that the bonds are identical. For the s and p orbitals to be identical or equivalent they must have changed shape or hybridized Be Be Cl Can participate in a σ bond potential energy
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2.2 Orbitals 4 sp hybridization 1s 2 2s 2 2p The combination of one atomic 2s orbital with one atomic 2p orbital will produce two hybridized molecular orbitals called sp hybridized orbital Be Orbital hybridization is a mathematical combination of the 2 s and 2 p wave functions to obtain wave functions for the new orbitals unhybridized p orbitals sp hybridized can form two σ bonds Be Cl Cl only one p orbital of chlorine’s shown Cl Be Cl Two σ -bonding MO (p + sp) (antibonding not shown) empty p orbitals not shown potential energy 2p 2sp
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2.2 Orbitals 5 Acetylene (HCCH) linear sp hybridized C 1s 2 2s 2 2p 2 4 valence electrons 1s 2 2s 2 2p 2 C H C C H Each carbon has two sigma bonds potential energy 1s 2 2sp 2p π bond is the sideways linear combination of two p orbitals 180° c a n f o r m σ b d C combine one s and one p orbital to form two sp hybridized orbitals What type of bond can the p orbitals form?
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2.2 Orbitals 6 Acetylene (HCCH) (only bonding orbitals shown)
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2.2 Orbitals 7 H H Valence Bond theory: So why is there hybridization. Remember hybridization is only a model to describe the shape of the bonding.
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2.2_orbitals_post - VSEPR(Valence Shell Electron-Pair...

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