Lab#4 part 2 Flashcards
The covalent bond (sigma bond) of a molecule experiences various types of
vibrations and rotations
Covalent bonds cause
causes atoms not be stationary and to fluctuate continously
what are vibrational motions defined by
stretching and bending modes, These movements are defined for diatomic or traitomic molecules
A change in the angle occurring between two bonds is known as
bending vibration
What are the 4 bending vibrations
wagging
twisting, rocking
scissocirng
A molecule consiting of (N) number of atoms has a total of ___ degrees of freedom
3 N
What happen in a non-linear molecule regarding degrees of freedom:
3 of these degrees of freedom are
rotational, 3 are translational and the remainder is fundamental
vibrations
What happens in a linear molecule
there are 3 translational degrees of freedom and
2 are rotational.
Linear molecules:
3N-5 degrees of vibrational modes
non-linear molecules:
3N-6 degrees of vibrational modes
H2O is a non-linear molecule due to the uneven distribution of the _____. O2 is more electronegative than H2 and carries a negative charge, while H has a partial positive charge. The total degrees of freedom will be______
electron density.
3(3)-6=9-6=3
classfication of IR bands
strong-covers most of y-axis, medium- falls about half of the y-axis, weak- about one third or less of the y-axis
classfication of IR bands
strong-covers most of y-axis, medium- falls about half of the y-axis, weak- about one third or less of the y-axis
What type of bond are displayed on the IR spectrum?
Only polar bonds
intensity of the bands depends on the magnitude of the
dipole moment associated with the bond in question
Strongly polar bonds such as carbonyl groups (C=O)
produce strong bands
Medium polarity bonds and asymmetric bonds produce
medium bands
Weakly polar bond and symmetric bonds produce
weak or nonobservable bands
