apoyos enalces. .pdf
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Apoyos U.III Enlaces
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Valence electrons are the outer shell electrons of an atom. The valence electrons are the electrons that participate in chemical bonding.
1 1 ns1
2 2 ns2
13 3 ns2np1
14 4 ns2np2
15 5 ns2np3
16 6 ns2np4
17 7 ns2np5
Group # of valence e- e- configuration
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Lewis Dot Symbols for the Representative Elements & Noble Gases
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Li + F Li+ F -
Enlace ionico
1s22s1 1s22s22p5 1s2 1s22s22p6
[He] [Ne]
Li Li+ + e-
e- + F F -
F - Li+ + Li+ F -
LiF
FORMA CORRECTA DE REPRESENTAR ESTRUCTURA DE LEWIS DE UN COMPUESTO CON ENLACE IONICO.
Thus, the simplest neutralizing ratio of Al3+ to O2− is 2:3; two
Al3+ ions have a total charge of +6, and three O2− ions have a
total charge of −6. So the empirical formula of aluminum oxide
is Al2O3, and the reaction is
Check Make sure that the number of valence electrons (24) is
the same on both sides of the equation. Are the subscripts in
Al2O3 reduced to the smallest possible whole numbers?
OTRO EJEMPLO DE ESTRUCTURA DE LEWIS DE COMPUESTOS CON ENLACE IONICO.
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A covalent bond is a chemical bond in which two or more electrons are shared by two atoms.
Why should two atoms share electrons?
F F +
7e- 7e-
F F
8e- 8e-
F F
F F
Lewis structure of F2
lone pairs lone pairs
lone pairs lone pairs
single covalent bond
single covalent bond
LOS ELECTRONES SE COMPARTEN .
EJEMPLO DE ESTRUCTURA DE LEWIS DE COMPUESTOS CON ENLACE COVALENTE.
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8e-
H H O + + O H H O H H or
2e- 2e-
Double bond – two atoms share two pairs of electrons
single covalent bonds
O C O or O C O
8e- 8e- 8e- double bonds
Triple bond – two atoms share three pairs of electrons
N N
8e- 8e-
N N
triple bond
or
EJEMPLO DE ESTRUCTURA DE LEWIS DE COMPUESTOS CON ENLACE COVALENTE.
RESONANCIA : Diferentes formas representar la estrucura de Lewis en una molecula, sin alterar sus propiedades físicas y químicas. Distribucion de enlaces y eletrones de maneras diferentes.
O O O + -
O O O + -
OJO; SEÑALAR QUE SON CARGAS PARCIALES CON EL SIMBOLO DELTA ( )
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Algunas Excepciones de la regla del octeto.
SF6
S
F
F
F
F F
F
PF5
B
F F
F BF3
Be F F
BeF2
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Lengths of Covalent Bonds
Bond Lengths
Triple bond < Double Bond < Single Bond
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Electronegativity is the ability of an atom to attract toward itself the electrons in a chemical bond.
Electron Affinity - measurable, Cl is highest
Electronegativity - relative, F is highest
X (g) + e- X-(g)
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The Electronegativities of Common Elements
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AB2 2 0 linear linear
Class
# of atoms bonded to
central atom
# lone pairs on
central atom Arrangement of electron pairs
Molecular Geometry
VSEPR
AB3 3 0 trigonal planar trigonal planar
AB4 4 0 tetrahedral tetrahedral
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bonding-pair vs. bonding- pair repulsion
lone-pair vs. lone-pair repulsion
lone-pair vs. bonding- pair repulsion
> >
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Formation of sp2 Hybrid Orbitals
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Formation of sp3 Hybrid Orbitals
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Formation of Covalent Bonds in CH4
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# of Lone Pairs +
# of Bonded Atoms Hybridization Examples
2
3
4
5
6
sp
sp2
sp3
sp3d
sp3d2
BeCl2
BF3
CH4, NH3, H2O
PCl5
SF6
How do I predict the hybridization of the central atom?
1. Draw the Lewis structure of the molecule.
2. Count the number of lone pairs AND the number of atoms bonded to the central atom
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Two Possible Interactions Between Two Equivalent p Orbitals
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