4.7 Spectroscopy

Infrared radiation can be absorbed making them bend and stretch more.

1) Stretch = distance between 2 atoms increases and decreases. 2) Bend = results in a change in bond angles.

-Mass of atoms in bond (heavier atoms vibrate slower) -Strength of bond (stronger bonds vibrate faster)

Bonds can only absorb radiation that has the same frequency as the bond that is absorbing it.

They absorb the longer wavelength of IR because it has the same frequency as the frequency of their natural bonds. Eventually they re-emitt this energy as radiation, which increases temperature of atmosphere.

Below 1500 wavelength that is generally not useful as they are hard to distinguish bonds without computer software.

Look at distinct peaks on graph and match the peaks to a bond based off wavelength of IR that each bond absorbs.

C=O O-H C=C

Used in breathalysers by passing a beam of IR through breath sample and detects IR absorption of compounds in breath. The more IR absorbed, the higher the reading, so more ______ in breath.

Molecules are ionised and an electron is fired at molecule making it lose an electron. This forms the molecular ion.

Shows the relative molecular mass of molecule and the detects detects the m/z ration of this ion. This shows the highest peak on the mass spectra.

In mass spectrometer, some M+ ions break down into smaller pieces known as fragments. These form smaller peaks on mass spectra.