Chemistry!! I have some questions. Please help me?

Question

1. Why does electromagnetis radiation in the ultraviolet region represent a larger energy transition than does radiation in the infrared region?
-I think it has something to do with the frequency or wavelenghts but i have no idea.

2. The wavelength of light is 310 nm. Calculate its frequency.
- I have no idea how to do this one

3. What is the wavelength of electromagnetic radiation if its frequency is 3.2 x 10 (-2) Hz?
- What??????

I'm so confused
Someone help me out?
Thanks if you can help
-j-

Answer 1

For all of these, the relationships you need are

E = hf
fλ = c

E is the energy of the photon
h is Planck's constant
f is the frequency
λ is the wavelength
c is the speed of light, 3 x 10^8 m / s.

(1) The first equation tells you that the energy of a photon is proportional to its frequency. Ultraviolet light has a larger frequency / lower wavelength than infrared light, so ultraviolet light has more energy per photon. That's why UV gives you a sunburn and IR does not.

(2) Use the second equation. Write the wavelength as 310 x 10-9 meters. plug in c, and solve for the frequency.

(3) Same deal; plug in the given frequency and the speed of light and solve for the wavelength.

Answer 2

I'm not sure about number 1, but for #2 and 3, use the rule that

frequency x wavelength = speed of light (C) = 3.0 x 10^8

So, for your problems, just divide C by what they give you to find the wavelength/frequency.