Lecture 7

Question 1

Electromagnetic radiation (EMR) definition

Answer 1

Waves composed of electric and magnetic fields that oscillate in directions perpendicular to direction of energy travel

Question 2

Electromagnetic radiation (EMR) equations

Answer 2

C=λV V= frequency
V= c/λ

E = hv
E=hc/λ

Question 3

High energy, _____wavelength, ____ V
Low energy, ______wavelength, ____ V

Answer 3

short, high
long, low

Question 4

Rank lowest to highest energy levels

Answer 4

radio ( lowest)
microwave
infrared
visible (400-800nm)
ultraviolet
x-ray
gamma ray (highest)

Question 5

what are the three types of molecular motion?

Answer 5

Translational –> from one point to another
Rotational –> rotation of a molecule
Vibrational –> compression and expansion of bonds

Question 6

What do molecules need to absorb infrared light?

Answer 6

Molecules must be IR active and able to undergo a change in their dipole moment

Question 7

Homonuclear molecules

Answer 7

(N2,O2,H2) Have zero dipole moment. IR inactive

Question 8

Heteronuclear molecules

Answer 8

(NO, CO, HCl) Have dipole moment. IR active

Question 9

Polyatomic molecules

Answer 9

Have more than 1 type of stretching. Symmetrical stretch is IR inactive and asymmetrical is IR active