Introduction to Organic Chemistry; Quantum mechanics and bonding

What are the four quantum numbers and what do they represent? What do quantum numbers N and L tell us??

Represents the most probable location and properties of an electron

n (principal quantum number) = energy level

higher n = greater distance from nucleus (and thus a greater energy level)

Orbitals start at 1 and increase…

L = Angular momentum or shape of the orbital

The numerical value of L cooresponds to a shape. For our scope, we are only focused on L = 0 and L = 1

When L = 0, we have a standard circular shape, also known as an S orbital

When L = 1, we have a dumbell shape, also known as a P orbital.

by the way, S = the shape of the orbit

but ALSO S = a sublevel

Same with P. P = the shape (Dumbell) and is also, a sublevel

Now how about quantum numbers M_l. and M_s?

M_L = magnetic quantum number, or the oritentation of the orbital.

You will now notice; that the numerical value of L is actually relevant to M_L.

know that -L < M_L < L (greater than or equal to

For instance, S = 0. This makes sense because because there is only one S orbital, so per energy level there is only one orbital the electron could be

P = 1 makes sense as well because there are indeed three orbitals per energy level, Px Py and Pz, so the electron must be in -1, 0, or 1.

Px doesnt neccesairly coorespond with -1. We don’t really have any way of telling where the electron is, anyways.

Thankfuly, l=2 and L=3 are beyond the scope of our class. For now.

M_S is extrodinarily simple. M_S is simply up spin or down spin. Ms is either +1/2 or -1/2. All you need to know is that you must place them firstly with parallel spins, and then pair them with the opposite spins.

Example of how you can use the quantum numbers to find the electron

It is not that hard.

For any give n energy level, what is higher; The P orbital or the S orbital? And, because of this, where is the orbital in relation to the nucleus?

The P orbital. The P orbital is farther from the nucleus compared to the S orbital.

Explain hybrydization

Hybrydization comes into play when standard orbitals cannot explain the location of the electron.

What are orbitals basically doing?

estimating electron density with 90-95% accuracy. Orbitals are clouds of electron density

What exactly occurs during a sigma bond? what kind of interference is this?

Direct overlap of orbitals. The electrons are essentially on top of each other. This is constructive inferference

What are the positive and negative phases of an electron’s wave function?

Basically; it’s positive on one side of the node and negative on the other.

Bonding at its core…

Sigma bonds result in…. what for energy?

A lower energy level, as bonding is energetically favorable

With every sigma bond, there is a…

constructive and deconstructive molecular orbit establisbed. the deconstructive is inidcated as sigma star, or an antibonding MO.

Antibonding is _____

Bonding is ______

__ Is Higher energy

__ Is lower energy

1. unstable/destructive

2. Stable/constructive

3. Antibonding

4. Bonding/ Sigma bonds