Chpt 1: Structure and Bonding in Organic Molecules Flashcards
what is organic chemistry the study of?
carbon and it’s compounds/molecules
what do we use organic chemistry for?
to understand chemicals produced by living things and to make things like drugs, plastics, food products, pesticides, petroleum products, etc
why is carbon so important in/to living things?
it’s a principle component in stuff like fat, sugars, protein, and nucleic acid
what are functional groups?
groups of atoms within a molecule that give the molecule its characteristic bonding/reactivity behavior
how are molecular structure and reactivity related?
the structure of a molecule determines the reactions that it can undergo
What is ionization potential?
The energy involved in losing an electron
What is electron affinity?
The energy involved in gaining an electron
What is electrostatic attraction?
The energy involved in bringing things together
what range of charge separations are considered to be polar?
ranges between 0.3 and 2.0
what does it mean to say that a molecule/lewis structure is charge separated?
it means that the electrons are not evenly distributed around the atoms
usually bc of differences in atom electronegativity
what 3 situations break the octet rule?
when a molecule has odd number of electrons
when a compound (usually from period 2) has too few valence electrons
when a compound contains elements bigger than phosphorus/period 2
what does it mean to say that a charge in a resonance structure is delocalized?
that the charge on the molecule is spread out in space, across the various resonance structures
How does one resonance structure for a molecule compare to another resonance structure for the same molecule?
Both have the same placement of atoms and the same overall formal charge but the placement of the electrons is different
When you’re writing resonance structures, are you allowed to change which atoms are bonded to which other atoms?
No. In each resonance structure, the same atoms must be bonded to each other in all structures
The only difference between the structures is the arrangement of the electrons
what properties determine how much a given resonance structure contributes to a resonance hybrid?
- number of octets (more octets, more contribution)
- degree to which electrons are positioned around the most electronegative atom (more electrons on the electronegative parts, more contribution)
- degree of neutralness (less charge separation, less dipole character, more contribution)
what’s the difference between and atomic orbital and molecular orbital?
atomic orbitals describe the wave functions inhabited by the electrons on a given atom.
molecular orbitals describe the OVERLAPPING of electron clouds between 2 separate atoms
what is a substituent?
an atom or group of atoms which replaces one or more hydrogen atoms on the parent chain of a hydrocarbon
what is the bond angle for single/sigma bonds in a hybridized carbon?
109.5 degrees tetrahedral
gives the zig zag/tetrahedral shape when all four bonds are hybridized
what is the bond angle for double (pi) bonds in a hybridized carbon?
120 degrees trigonal planar
looks similar to sigma bonds in line structure
what is the bond angle for triple (sigma, pi, pi) bonds in a hybridized carbon?
180 degrees linear
makes a straight line on the line structure
what is an isomer?
what you call it when a molecules have the same molecular formula but differ from one another in some specific way
exp. 2 molecules with the same formula but with the atoms connected differently
how many types of isomers are there?
at least 2
what is a constitutional isomer?
an isomer that differs from other molecules (with the same molecular formula) by the way its atoms are attached
in resonance structures, do electrons ever jump from one atom to a completely different atom?
no. They have to be shared with/moved about the original atom that they belong to
in resonance structures, which atoms can get away with having less than an octet?
Carbon
A structure whose carbon has less than an octet is still considered valid
can you move/adjust single bonds to make resonance structures?
No. You can only adjust double/pi bonds (because these are in the pi system)
Adjusting single bonds would change the connectivity of the molecule
Which bond is weaker: sigma bond or pi bond?
Pi bond
The ‘head on’ sigma bond is more stable/less reactive than the ‘side on’ pi bond, which is less stable/more rective
Which bond has more energy: sigma bonds or pi ponds?
Pi bonds
They come from regular p orbitals which have higher energy that s and sp orbitals; the higher energy is what makes them more reactive
what are the steps for drawing constitutional/structural isomers?
- determine the DOU
- draw the carbon chain
- add the other non carbon components as substituents (configured as functional groups if you can)
- move the components around
- Remove a carbon from the end of the chain, and add it back as a substituent
- move the other components around
- repeat and so on and so forth
