Intermolecular Forces and Properties

Increased spin-lattice relaxation time T₁ causing broadened NMR peaks.

Improved resolution due to decreased proton-proton interaction through hydrogen bonding with solvent molecules.

Shifts in chemical shifts towards lower field strength due to increased shielding effects.

Reduced signal-to-noise ratio because nonpolar solutes dissolve poorly in polar solvents.

n→π* transition for an amine group.

n→σ* transition for alcohol hydroxyl groups.

σ→σ* transition for single-bonded carbons in alkanes.

π→π* transition for conjugated dienes.

X-rays.

Infrared (IR).

Ultraviolet (UV).

Radio waves.

Boron

Lithium

Potassium

Sodium

Microwaves

Radio waves

Visible light

Infrared radiation

The energy gap is larger for the molecule absorbing light with a longer wavelength.

Both molecules have identical energy gaps between their ground and excited states.

The energy gap is smaller for the molecule absorbing light with a longer wavelength.

No inference can be made about the energy gaps from the wavelengths of absorbed light.

A proton moves to a lower energy level, absorbing a photon of energy.

An electron moves to a lower energy level, emitting a photon of energy.

An electron moves to a higher energy level, absorbing a photon of energy.

A proton moves to a higher energy level, emitting a photon of energy.

infrared

microwave

x-rays

visible light

All molecules contain similar structures, thus resulting in identical emission patterns.

Due to the quantized nature of a particular element’s shells, only certain amounts of energies are released, leading to distinct peaks within the observed spectra.

Because electrons absorb and emit at random intervals, causing unique spaced bands to form across the spectrum.

At elevated heat conditions, all atomic vibrations synchronize, consequently producing sharp narrow bands.

Decreases.

Increasses.

Remains constant.

Stops completely.