general and inorganic chemistry i. - lecture 5
TRANSCRIPT
General and Inorganic Chemistry I.Lecture 5
István Szalai
Eötvös University
Outline
1 28
Lewis Formulas and the Octet Rule
In most of their compounds, the representative elements (s andp �eld) achieve noble gas con�gurations.
2 28
Lewis Formulas and the Octet Rule
In most of their compounds, the representative elements (s andp �eld) achieve noble gas con�gurations.
2 28
Lewis Formulas and the Octet Rule
In most of their compounds, the representative elements (s andp �eld) achieve noble gas con�gurations.
2 28
Resonance and Delocalization
3 28
Dative Bond
[Fe(CN)]4−6
4 28
Dative Bond
[Fe(CN)]4−6
4 28
Limitations of the Octet Rule
Compounds in which the central element needs a share in lessthan eight valence shell electrons. bigskip
5 28
Limitations of the Octet Rule
Compounds in which the central element needs a share in morethan eight valence shell electrons.
6 28
Limitations of the Octet Rule
Compounds or ions with odd number of electrons.
7 28
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)
8 28
Bond Energy, Bond Length
bond length (pm) bond energy (kJ/mol)H−H 74 436C−C 154 347N−N 140 159O−O 132 138F−F 128 159Si−Si 234 176C=C 134 611O=O 121 498C≡C 121 837N≡N 110 946
9 28
Bond Polarity, Dipole Moments
~µ = Q · ~d
10 28
Molecular Polarity
~µ = Q · ~d
11 28
Metallic Bond
It results from the electrical attractions among positivelycharged metal ions and mobile, delocalized electrons belongingto the crystal as a whole.
12 28
Continuous Range of Bonding Types
∆EN = 0 apolar covalent or metallic bond0 < ∆EN < 2 polar covalent or metallic bond2 < ∆EN ionic bond
13 28
VSEPR Theory
Valence shell electron pair repulsion theory: Each set of valenceshell electrons on a central atom is signi�cant. The sets ofvalence shell electrons on the central atom repel one another.They are arranged about the central atom so that repulsionsamong them are as small as possible. Lone pairs of electronsoccupy more space than bonding pairs.
A: central atom, X: shared electron pairs, E: lone (unshared) pairs
AXnEm
14 28
VSEPR Theory
AX2 BeCl2, CdI2, HgBr2 linear
AX3 BF3,BF3, NO−3 trigonal planar
AX2E SO2, NO−2 angular
15 28
VSEPR Theory
AX2 BeCl2, CdI2, HgBr2 linear
AX3 BF3,BF3, NO−3 trigonal planar
AX2E SO2, NO−2 angular
15 28
VSEPR Theory
AX2 BeCl2, CdI2, HgBr2 linear
AX3 BF3,BF3, NO−3 trigonal planar
AX2E SO2, NO−2 angular
15 28
VSEPR Theory
AX4 CH4, CCl4, NH+4 tetrahedral
AX3E NH3, SO2−3 trigonal pyramidal
AX2E2 H2O angular
16 28
VSEPR Theory
AX4 CH4, CCl4, NH+4 tetrahedral
AX3E NH3, SO2−3 trigonal pyramidal
AX2E2 H2O angular
16 28
VSEPR Theory
AX4 CH4, CCl4, NH+4 tetrahedral
AX3E NH3, SO2−3 trigonal pyramidal
AX2E2 H2O angular
16 28
AX5 PF5, SbCl5 trigonal bipyramidal
AX4E SF4 seesaw
AX3E2 ClF3 T-shaped
AX2E3 XeF2, I−3 linear
17 28
AX5 PF5, SbCl5 trigonal bipyramidal
AX4E SF4 seesaw
AX3E2 ClF3 T-shaped
AX2E3 XeF2, I−3 linear
17 28
AX5 PF5, SbCl5 trigonal bipyramidal
AX4E SF4 seesaw
AX3E2 ClF3 T-shaped
AX2E3 XeF2, I−3 linear
17 28
AX5 PF5, SbCl5 trigonal bipyramidal
AX4E SF4 seesaw
AX3E2 ClF3 T-shaped
AX2E3 XeF2, I−3 linear
17 28
AX6 SF6, SeF6 octahedral
AX5E BrF5 square pyramidal
AX4E2 XeF4 square planar
18 28
AX6 SF6, SeF6 octahedral
AX5E BrF5 square pyramidal
AX4E2 XeF4 square planar
18 28
AX6 SF6, SeF6 octahedral
AX5E BrF5 square pyramidal
AX4E2 XeF4 square planar
18 28
Valence Bond (VB) Theory
Valence bond theory describes covalent bonding as electron pairsharing that results from the overlap of orbitals from two atoms.Usually, ”pure atomic” orbitals do not have the correct energiesand orientations to describe the where the electrons are whenan atom is bounded to other atoms. When other atoms arenearby as in a molecule, an atom can combine its valence shellorbitals (hybridization) to form a new set of orbitals (hybridorbitals).
19 28
Valence Bond (VB) Theory
Linear GeometryBeCl2: Be [He] 2s2 Cl [Ne] 3s2 3p5Be 2s2 −−−−−→
hybridizesp
20 28
Valence Bond (VB) Theory
Trigonal Planar GeometryBF3: B [He] 2s2 2p1 F [He] 2s2 2p5B 2s2 2p1 −−−−−→
hybridizesp2
21 28
Valence Bond (VB) Theory
Tetrahedral GeometryCH4: C [He] 2s2 2p2 H 1s1C 2s2 2p2 −−−−−→
hybridizesp3
22 28
Valence Bond (VB) Theory
Trigonal Pyramidal GeometryH3: N [He] 2s2 2p3 H 1s1N 2s2 2p3 −−−−−→
hybridizesp3
23 28
Valence Bond (VB) Theory
Angular GeometryH2O: O [He] 2s2 2p4 H 1s1O 2s2 2p4 −−−−−→
hybridizesp3
24 28
Valence Bond (VB) Theory
Trigonal Bipyramidal GeometryPF5: P [Ne] 3s2 3p3 F [He] 2s2 2p5P 3s2 3p3 −−−−−→
hybridizesp3d
25 28
Valence Bond (VB) Theory
Octahedral GeometrySF6: S [Ne] 3s2 3p4 F [He] 2s2 2p5S 3s2 3p4 −−−−−→
hybridizesp3d2
26 28
Valence Bond (VB) Theory
Double BoundsA double consists of one sigma and one pi bond. A sigma bondresulting from head-on overlap of atomic orbitals. A pi bondresulting from side-on overlap of atomic orbitals.C 2s2 2p2 −−−−−→
hybridizesp2
27 28
Valence Bond (VB) Theory
Triple BoundsA triple bound consists of one sigma and two pi bonds.C 2s2 2p2 −−−−−→
hybridizesp
28 / 28