Hybrid Orbitals

polyatomic molecules polyatomic molecules The number of bonds formed The number of bonds formed Their geometries Their geometries sp Hybrid Orbitals sp Hybrid Orbitals Example BeF2 Example BeF2 Lewis structure Lewis structure The VSEPR model predicts this structure will be linear The VSEPR model predicts this structure will be linear What would valence bond theory predict about the structure? What would valence bond theory predict about the structure?

Electron configuration Electron configuration 9 F 1s 2 2s 2 2p 5 9 F 1s 2 2s 2 2p 5 4 Be 1s 2 2s 2 4 Be 1s 2 2s 2 two unpaired electrons two unpaired electrons unpaired electron in a 2p orbital In the ground state, there are no unpaired electrons obtain an unpaired electron by promoting an electron from the 2s orbital to the 2p orbital Be atom can form two covalent bonds with F atoms The structure of BeF 2 is linear and the bond lengths are identical

We can combine 2s and 2p orbitals to produce a "hybrid" orbital ( sp ( We can combine 2s and 2p orbitals to produce a "hybrid" orbital ( sp ( The orbital diagram for this hybridization

Note Note When orbitals are mixed (hybridized) When orbitals are mixed (hybridized) عند مزج اوخلط المدارات يكون عدد المدرات المهجنه الناتجة مساوي لعدد المدارت الداخلة في التهجين The number of hybrid orbitals produced is equal to the sum of the orbitals being hybridized The number of hybrid orbitals produced is equal to the sum of the orbitals being hybridized hybrid orbital is identical except that they are oriented in different directions hybrid orbital is identical except that they are oriented in different directions المدرات المهجنة تكون متطابقة وموجهه في اتجاهات مختلفة المدرات المهجنة تكون متطابقة وموجهه في اتجاهات مختلفة

sp 2 and sp 3 Hybrid Orbitals BF 3 BF 3 Electron configuration Electron configuration 9 F 1s 2 2s 2 2p 5 9 F 1s 2 2s 2 2p 5 5 B 1s 2 2s 2 2p 1 5 B 1s 2 2s 2 2p 1 three unpaired electrons three unpaired electrons ثلاث الكترونات منفردة في غلاف التكافؤ من مدارات مختلفه ثلاث الكترونات منفردة في غلاف التكافؤ من مدارات مختلفه three sp 2 hybrid orbitals have a trigonal planar arrangement to minimize electron repulsion three sp 2 hybrid orbitals have a trigonal planar arrangement to minimize electron repulsion تنتج ثلاث مدارات مهجنه من نوع sp 2 تتخذ شكل مثلث مستوي لتقليل التنافر الالكتروني تنتج ثلاث مدارات مهجنه من نوع sp 2 تتخذ شكل مثلث مستوي لتقليل التنافر الالكتروني

trigonal planar

We can also mix with all 3p orbitals in the same subshell We can also mix with all 3p orbitals in the same subshell Example CH 4 Example CH 4 6 C 1s 2 2s 2 2p 2 6 C 1s 2 2s 2 2p 2 hybridization Four atomic orbitals (2s + 3 × 2p) mix to form four hybrid orbitals (4 × sp3)

H 2 O H 2 O 8 O 1s 2 2s 2 2p 4 8 O 1s 2 2s 2 2p 4

Hybridization Involving d Orbitals Hybridization Involving d Orbitals PF 5 15 P 1s 2 2s 2 2p 6 3s 2 3p 3 3d PF 5 15 P 1s 2 2s 2 2p 6 3s 2 3p 3 3d Similarly hybridizing one s, three p and two d orbitals produce six identical hybrid sp 3 d 2 orbitals in an octahedral geometry hybridizing one s, three p and one d orbitals produce five identical hybrid sp 3 d orbitals

NH 3 7 N 1s 2 2s 2 2p 3 NH 3 7 N 1s 2 2s 2 2p 3 Lewis structure Lewis structure VSEPR indicates tetrahedral geometry with one non-bonding pair of electrons (trigonal pyramidal ) VSEPR indicates tetrahedral geometry with one non-bonding pair of electrons (trigonal pyramidal ) Tetrahedral arrangement indicates four equivalent electron orbitals Tetrahedral arrangement indicates four equivalent electron orbitals

Hybrid Orbitals Number of Orbitals Valence Electron Pair Geometry sp2Linear sp 2 3 Trigonal Planar sp 3 4Tetrahedral Sp 3 d 5 Trigonal Bipyramidal Sp 3 d 2 6Octahedral

Multiple Bonds Bond Types σ-bond results from s-s s-p p-p π-bond results from overlap two p-orbitals

Why double bonds occur frequently with C, N, and O but not with larger molecules

6 C 1s 2 2s 2 2p 2 Ethylene 6 C 1s 2 2s 2 2p 2 These p-orbitals can overlap, sideways: π-bond

Delocalized Orbitals Molecules with two or more resonance structures can have π-bond that extend over more than two bonded atoms.Electron on π-bond that extend over more two atoms are said to be delocalized

Home work Draw sketches illustrating the overlap between the following orbitals on two atoms Draw sketches illustrating the overlap between the following orbitals on two atoms 1. 2s orbital on each 2. 2p z orbital on each( assume that the atoms are on the z axis ) 3. The 2s orbital on one and 2p z orbital on the other Indicate the hybrid orbital set used by the central atom in each of the following molecules and ions Indicate the hybrid orbital set used by the central atom in each of the following molecules and ions BH 4 -, NH 3, XeF 2, BI 3, PF 6 - What set of hybrid orbitals is used by central atom in each of the following molecules and ions What set of hybrid orbitals is used by central atom in each of the following molecules and ions H 3 O +, CS 2, SO 4 2-, I 3 -, XeF 4 H 3 O +, CS 2, SO 4 2-, I 3 -, XeF 4

Determine the hybrid orbitals on the nitrogen in angle 1 and the C in angle 2.