Quick little Gen Chem Question about Wavelength and Freq

Mrhyde

Becoming Dr. Jekyll
I have gotten all these type of questions correct but find confusion on this particular question:

Which of the following transitions in a hydrogen atom represent absorption of the smallest frequency photon?
A) n=1 to n=2
b) n= 5 to n =6
C) n= 4 to n=1

Thought Process :
Obviously we can eliminate C immediately because Absorption's go "upwards".

So now my dilemma is choosing between A and B ? usually on all these questions the answers have not been so close as they are here, so that's why I am confused since an obvious difference between A and B does not "jump" out at me.

So I know the smallest frequency would be equal to which has the smallest amount of energy which is also equal to which has the smallest gap between the answer choices ( since the bigger the gap the more energy )

--> But A and B are both at a difference of one, so they are both the same small gap apart ?

----> The answer is B n= 5 to n =6 .... but why ? are smaller numbers that are closer to the number 1, considered Higher Energy or something ?

Mrhyde

Becoming Dr. Jekyll You're correct that the associated energy with the n = 1 -> 2 transition is the highest; however, the question asks for the lowest frequency of the absorbed photon. Since E = hv (Planck's equation) where v = frequency, energy is proportional to frequency. As such, you want to find the absorption transition with the lowest energy, thus B! Hope that helps Before I even get a chance to read your answer which I will read it right now , HOW ON EARTH DID YOU ANSWER SO QUICKLY AND ANSWER WITH THE TIME TO MAKE A DRAWING lol I literally just clicked submit and its been up for 20 seconds hahaha thats amazing. I'll read your answer now, thank you

Mrhyde

Becoming Dr. Jekyll You're correct that the associated energy with the n = 1 -> 2 transition is the highest; however, the question asks for the lowest frequency of the absorbed photon. Since E = hv (Planck's equation) where v = frequency, energy is proportional to frequency. As such, you want to find the absorption transition with the lowest energy, thus B! Hope that helps AWESOME answer man I appreciate this alot thank you. ! So Its true then, that anything close to the #1 will be considered higher energy ?

Mrhyde

Becoming Dr. Jekyll
You got it. Essentially, transitions from low energy states to high energy states have greater associated energies when the transition sets have lower n values. n = 1 -> 2 transition always has the highest associated energy (absorption and emission).
Awesome I understand it perfectly now thank you

• maga1994

Mrhyde

Becoming Dr. Jekyll
You got it. Essentially, transitions from low energy states to high energy states have greater associated energies when the transition sets have lower n values. n = 1 -> 2 transition always has the highest associated energy (absorption and emission).
By the way just out of curiosity, do you know what topic in gen chem this would be considered ?

P0W3RL1FT3R

5+ Year Member
Excuse my ignorance, but is a small frequency the same as saying a long wavelength?