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32 terms

Kaplan MCAT OChem Ch. 3: Bonding

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two types of chemical bonds
ionic and covalent
ochem concerned w/ this type of bonding
covalent (polar and nonpolar) => effect phys. properties
s orbital
spherical and symm., centered on the nucleus
p orbital
composed of two lobes located symm. about the nucleus and contains a node in the nucleus

has 3 diff. orientations
node
an area where the prob. of finding an electron is zero
d orbitals
composed of 4 symm. lobes and contains 2 nodes.

4 of them are clover shaped and fifth looks like a donut wrapped around center of a p orbital.
molecular orbitals
two atomic orbitals combine and form this
molecular orbitals
obtained math. by adding or subtracting the wave functions of atomic orbitals
bonding orbitals
sign of wave functions same => this lower energy (more stable) forms
antibonding orbitals
if signs are different, higher energy (less stable)
sigma bond
when molecular orbital is formed head to head or tail to tail of two s's, two p's, or one s and p => this results
shorter bonds
atoms more close together; stronger than longer bonds
pi bond
two unhybridized p orbitals line up in parallel (side by side) fashion, their electron clouds overlap, and a bonding molecular orbitals is formed
double bond
one pi bond on top of an existing single bond
triple bond
a sigma bond and two pi bonds
double and triple bonds
hinder rotation => lock atoms into position
pi bonds
can't exist indie of sigma
pi bonds
weaker the sigma, and it's possible to break only one of bonds in DB, leaving a single bond intact (geo isomers converted)
pi bonds
although weak than sigma in isolation, strength is additive
carbon electron config
1s^(2)2s^(2)2p^(2)

needs 4 electrons to complete its octet

in methane, sigma bonds are equivalent
sp3 hybrid
combine 3 p and 1 s => 4sp3
sp3 hybrid
all four of orbitals point toward vertices of a tetrahedron to min repulsion => prefer tetrahedral geo
sp3 hybrid
25% s, 75% p
sp2
one s, two p's
sp2
3rd p orbital left unhybridized, orbital that partcipates in the pi bond

DB
sp2
three of orbitals are 120 degrees apart
sp
triple bond
sp
two p orbitals to form pi bonds

third p orbital combines w/ s orbital to from two sp hybrid
sp
orbitals are 180 degrees apart
bonding orbitals
share same sign and energetically favorable
hybridization
making all bonds to central atom equivalent to each other
pi bond
e density is conc. above and below the bonding axis