3.4, 3.5, & 3.6: Hybridization, Sigma/Pi Bonds, and delocalization
What is hybridization practically?
a mixing of atomic orbitals to produce a new set of orbitals that are better arranged in space for covalent bonding (form the right orientation in space)
What is the definition of hybridization?
a modification of the localized electron model to account for the observation that atoms seem to use special atomic orbitals in forming molecules.
Molecules with two or more resonance structure can have...
bonds that extend over more than two bonded atoms.
What are pi bonds
bonds used to provide the extra electrons needed to fulfill the octet requirements
In every bond there is at least one ______
electron localized in the space between the atoms ( a sigma bond)
How is a pi bond formed?
formed by the overlap of two unhybridized parallel p-orbitals through the areas of low electron density. This corresponds to the orbitals combining at the side of the lobes and placed stringent geometric requirements on the arrangement of the atoms in space in order to establish the parallel qualities that are essential for bonding.
How is a sigma bond formed?
from the overlap of two hybrid orbitals through areas of maximum electron density. This corresponds to the orbitals combining at the tips in the orbitals.
Where are electrons in a sigma bond localized?
in the region between two bounded atoms and do not make a significant contribution to the bonding between any other atoms.
What bonds does a single bond have?
one sigma
What bonds does a double bond have?
one sigma, one pi
What bonds does a triple bond have?
one sigma, two pi
Where does hybridization occur?
only around the central atom
What orbitals are pi bonds formed by?
p
What orbitals are sigma bonds formed by?
p or s
Which is stronger, sigma or pi bond?
sigma
Which is stronger, sigma or sigma and pi?
sigma and pi
What are the two bonds in Hybridization Theory
sigma bonds, and pi bonds
What is the hybrid orbital for linear
sp
What is the hybrid orbital for trigonal planar
sp²
What is the hybrid orbital for tetrahedral
sp³
What is the hybrid orbital for trigonal bipyramidal
sp³d
What is the hybrid orbital for octahedral
sp³d²
What are resonance structures
structures showing that there is more than one structure for a molecule. They are extreme forms of the structure. The actual electrons lie imbetween the two.
What are sigma bonds
the primary bonds used to covalently attach atoms to each other
How are resonance structures usually drawn?
with a double headed arrow in between them
Which has a delocalized structure? RCOOH or RCOO⁻?
-RCOO⁻ because in RCOOH, one of the oxygens is bonded differently with a hydrogen
T or F, when asked to draw a structure of a species, you must also draw the delocalized structure
F. only draw one of the structures if not specifically asked to draw the delocalised structure
How is benzene have a different type of bonding?
It has a pi delocalized ring of electrons, which extends all around the ring of carbons
What is a dative covalent bond in terms of orbitals?
When atomic orbitals containing two electrons overlaps with and empty orbital
What is delocalization
a characteristic of electrons in pi bonds when there is more than one position for a double bond within the molecule.
How do you recognize molecules which are likely to have delocalized pi system?
- draw lewis structure - if it is possible to draw more than one lewis structure, where the only difference is the placement of a double bond (and a lone pair if there is one), then it is likely that the molecule/ ion will have a delocalized structure
Why are the bond lengths in ozone the same length?
-Because of the delocalization theory -At first, it seems that the ozone molecule is unsymmetrical, then the -the p orbital on the first oxygen can overlap with the p orbital on the second oxygen. The electron pair is now spread over the entire molecule
Delocalized electrons are...
-Electrons in pi bonds that extend over more than two atoms -The sharing of a pair of electrons between three or more molecules
