General and Inorganic Chemistry I. Lecture 1 István Szalai Eötvös University István Szalai (Eötvös University) Lecture 1 1 / 29 Outline István Szalai (Eötvös University) Lecture 1 2 / 29
Lewis Formulas and the Octet Rule In most of their compounds, the representative elements (s and p field) achieve noble gas configurations. István Szalai (Eötvös University) Lecture 1 3 / 29 Resonance and Delocalization István Szalai (Eötvös University) Lecture 1 4 / 29
Dative Bond [Fe(CN)] 4 6 István Szalai (Eötvös University) Lecture 1 5 / 29 Limitations of the Octet Rule Compounds in which the central element needs a share in less than eight valence shell electrons. bigskip István Szalai (Eötvös University) Lecture 1 6 / 29
Limitations of the Octet Rule Compounds in which the central element needs a share in more than eight valence shell electrons. István Szalai (Eötvös University) Lecture 1 7 / 29 Limitations of the Octet Rule Compounds or ions with odd number of electrons. István Szalai (Eötvös University) Lecture 1 8 / 29
Bond Order single bond (σ bond [s s, s p, p p]) double bound (1 σ bond + 1 π bond [p p]) triple bound (1 σ bond + 2 π bonds) István Szalai (Eötvös University) Lecture 1 9 / 29 Bond Energy, Bond Length bond length (pm) bond energy (kj/mol) H H 74 436 C C 154 347 N N 140 159 O O 132 138 F F 128 159 Si Si 234 176 C=C 134 611 O=O 121 498 C C 121 837 N N 110 946 István Szalai (Eötvös University) Lecture 1 10 / 29
Bond Polarity, Dipole Moments µ = Q d István Szalai (Eötvös University) Lecture 1 11 / 29 Molecular Polarity µ = Q d István Szalai (Eötvös University) Lecture 1 12 / 29
Metallic Bond It results from the electrical attractions among positively charged metal ions and mobile, delocalized electrons belonging to the crystal as a whole. István Szalai (Eötvös University) Lecture 1 13 / 29 Continuous Range of Bonding Types EN = 0 apolar covalent or metallic bond 0 < EN < 2 polar covalent or metallic bond 2 < EN ionic bond István Szalai (Eötvös University) Lecture 1 14 / 29
VSEPR Theory Valence shell electron pair repulsion theory: Each set of valence shell electrons on a central atom is significant. The sets of valence shell electrons on the central atom repel one another. They are arranged about the central atom so that repulsions among them are as small as possible. Lone pairs of electrons occupy more space than bonding pairs. A: central atom, X: shared electron pairs, E: lone (unshared) pairs AX n E m István Szalai (Eötvös University) Lecture 1 15 / 29 VSEPR Theory AX 2 BeCl 2, CdI 2, HgBr 2 linear AX 3 BF 3,BF 3, NO 3 trigonal planar AX 2 E SO 2, NO 2 angular István Szalai (Eötvös University) Lecture 1 16 / 29
VSEPR Theory AX 4 CH 4, CCl 4, NH + 4 tetrahedral AX 3 E NH 3, SO 2 3 trigonal pyramidal AX 2 E 2 H 2 O angular István Szalai (Eötvös University) Lecture 1 17 / 29 AX 5 PF 5, SbCl 5 trigonal bipyramidal AX 4 E SF 4 seesaw AX 3 E 2 ClF 3 T-shaped AX 2 E 3 XeF 2, I 3 linear István Szalai (Eötvös University) Lecture 1 18 / 29
AX 6 SF 6, SeF 6 octahedral AX 5 E BrF 5 square pyramidal AX 4 E 2 XeF 4 square planar István Szalai (Eötvös University) Lecture 1 19 / 29 Valence Bond (VB) Theory Valence bond theory describes covalent bonding as electron pair sharing that results from the overlap of orbitals from two atoms. Usually, pure atomic orbitals do not have the correct energies and orientations to describe the where the electrons are when an atom is bounded to other atoms. When other atoms are nearby as in a molecule, an atom can combine its valence shell orbitals (hybridization) to form a new set of orbitals (hybrid orbitals). István Szalai (Eötvös University) Lecture 1 20 / 29
Valence Bond (VB) Theory Linear Geometry BeCl 2 : Be [He] 2s 2 Cl [Ne] 3s 2 3p 5 Be 2s 2 sp István Szalai (Eötvös University) Lecture 1 21 / 29 Valence Bond (VB) Theory Trigonal Planar Geometry BF 3 : B [He] 2s 2 2p 1 F [He] 2s 2 2p 5 B 2s 2 2p 1 sp 2 István Szalai (Eötvös University) Lecture 1 22 / 29
Valence Bond (VB) Theory Tetrahedral Geometry CH 4 : C [He] 2s 2 2p 2 H 1s 1 C 2s 2 2p 2 sp 3 István Szalai (Eötvös University) Lecture 1 23 / 29 Valence Bond (VB) Theory Trigonal Pyramidal Geometry H 3 : N [He] 2s 2 2p 3 H 1s 1 N 2s 2 2p 3 sp 3 István Szalai (Eötvös University) Lecture 1 24 / 29
Valence Bond (VB) Theory Angular Geometry H 2 O: O [He] 2s 2 2p 4 H 1s 1 O 2s 2 2p 4 sp 3 István Szalai (Eötvös University) Lecture 1 25 / 29 Valence Bond (VB) Theory Trigonal Bipyramidal Geometry PF 5 : P [Ne] 3s 2 3p 3 F [He] 2s 2 2p 5 P 3s 2 3p 3 sp 3 d István Szalai (Eötvös University) Lecture 1 26 / 29
Valence Bond (VB) Theory Octahedral Geometry SF 6 : S [Ne] 3s 2 3p 4 F [He] 2s 2 2p 5 S 3s 2 3p 4 sp 3 d 2 István Szalai (Eötvös University) Lecture 1 27 / 29 Valence Bond (VB) Theory Double Bounds A double consists of one sigma and one pi bond. A sigma bond resulting from head-on overlap of atomic orbitals. A pi bond resulting from side-on overlap of atomic orbitals. C 2s 2 2p 2 sp 2 István Szalai (Eötvös University) Lecture 1 28 / 29
Valence Bond (VB) Theory Triple Bounds A triple bound consists of one sigma and two pi bonds. C 2s 2 2p 2 sp István Szalai (Eötvös University) Lecture 1 29 / 29