Every nucleus has a _____

Charge - The charge spins around an axis

As the nuclear charge spins, it generates a ______

Magnetic moment

How many potential spins can a nucleus of I have?

2(l) + 1

For a nuclei w/ I = 1/2, how many spin states are there? What are they?

Two potential spin states - (alpha, low energy), (beta, high energy)

What is the "spin flip" ?

Nuclei getting excited from alpha to beta spin state - Radio frequency to excite matches energy of delta E

What is resonance frequency?

Frequency where a nucleus undergoes spin flip - Excited to higher E spin the relax back down

What 3 things can you get from an NMR spectrum?

- Integration - Chemical shift - Spin-spin coupling

If protons are chemically eq, they will resonate at the same frequency in an NMR and appear as ____ signal

One resonance

The area underneath each NMR signal reflects what?

The integration - Number of p+ the signal represents

All nuclei are protected from the applied magnetic field by ______

The circulation of their own e-

The circulation of e- around a nucleus generates a _______

Localized magnetic field

How do the localized and applied magnetic field interact?

Localized opposed applied (Bo), which protects the nucleus from the full effect of Bo

What is shielding?

More e- density at nucleus and chemical shift is farther upfield (low number values)

What is deshielding?

Less e- density at nucleus and chemical shift is farther downfield (high values)

How does electronegativity influence chemical shift?

- Cl, F, O will deshield (O will do it most) - The farther the atom is from the EWG, the less deshielding it'll experience

What electropositive atom is shielding?

Si

As more EWG are added, neighboring atoms will be _____________

Deshielded (downfield)

As more EDG are added, neighboring atoms will be ____________

Shielded (upfield)

Placing an e- pair on an atom makes it....

Negatively charged - More e- density - Shielded

Taking an e- pair away from an atom makes it....

Positively charged - Less e- density - Deshielded

What is anisotropy?

Pi bonds have e- that are more loosely bound than single bonds

If the induced magnetic field is opposing Bo, a ________ effect will occur

Shielding

If the induced magnetic field is aligned w/ Bo, a _______ effect will occur

Deshielding

Describe what the nuclei look like for an alkene

Nuclei above/below the C=C are shielded by induced magnetic field

Describe what the nuclei look like for an aromatic

Nuclei above/below C=C are shielded by induced magnetic field

Describe what the nuclei look like for an alkyne

Nuclei above/below C triple bond C are deshielded by induced magnetic field

What is a sign of an exchangable p+ in NMR?

Broad signal

What does intermolecular mean?

Interactions between molecules

What does intramolecular mean?

Interactions between atoms on same molecule

The # of lines in a signal is predicted by _____

N + 1

What does pascals triangle represent?

The heights of sigals - All in ratios

What are the 3 types of coupling?

Geminal, Vicinal, Allylic

What are diastereotopic p+?

- Not identical or chemically eq

What is the formula for DOU?

[(2 x C) + 2] - H + N - X ---------------------------- 2