2. Dipole moment is
µ=q*l
q= charge
l=distance
Bond Polarisation:
Consider a bond between two atoms, A and B. If the atoms
are equally electronegative, both have the same tendency to
attract the bonding pair of electrons, and so it will be found
on average half way between the two atoms:
You will find this sort of bond in, for example, H2 or
Cl2 molecules.
The electrons are actually in a molecular orbital, and are
moving around all the time within that orbital. This sort of
bond could be thought of as being a "pure" covalent bond -
where the electrons are shared evenly between the two
atoms.
3. If one atom B is more electronegative than A
B will attract the electron pair rather than A .
That means that the B end of the bond has more than its fair
share of electron density and so becomes slightly negative.
At the same time, the A end (rather short of electrons)
becomes slightly positive.
A polar bond is a covalent bond in which there is a
separation of charge between one end and the other - in
other words in which one end is slightly positive and the
other slightly negative. Examples include most covalent
bonds. The hydrogen-chlorine bond in HCl or the
hydrogen-oxygen bonds in water are typical.
4. Rotational spectroscopy is concerned with the
measurement of the energies of transitions
between quantized rotational states of
molecules in the gas phase.
5. Incident electromagnetic waves can excite the
rotational levels of molecules provided they have
an electric dipole moment. The electromagnetic
field exerts a torque on the molecule. The spectra
for rotational transitions of molecules is typically
in the microwave region of the electromagnetic
spectrum. The rotational energies for rigid
molecules can be found with the aid of the
Schrodinger equation. The diatomic molecule can
serve as an example of how the determined
moments of inertia can be used to calculate bond
lengths.
6. involves the interaction of IR radiation with
matter. It covers a range of techniques, mostly
based on absorption spectroscopy. As with all
spectroscopic techniques, it can be used to identify
and study chemicals. Samples may be solid, liquid,
or gas. The method or technique of infrared
spectroscopy is conducted with an instrument
called an infrared spectrometer (or
spectrophotometer) to produce an infrared
spectrum. An IR spectrum can be visualized in a
graph of infrared light absorbance on the vertical
axis vs. frequency or wavelength on the horizontal
axis.
