I need help with 3 and 5. Thanks in advance! 2. What is the energy, frequency an

Question

I need help with 3 and 5. Thanks in advance! 2. What is the energy, frequency and wavelength of photons invloved in a transition from n =2 to n= 4 levels in a hydrogen atom? Will photons absorbed or emitted? 3. Without any calculations, select all transition that will result in emission of Photons and then rank these transition according to the wavelength of photons emitted. 4. When Vernier readings (degree) were plotted on y-axis, and wavelengths of line-spectra (nm) for Hg-lamp were plotted on x-axis, the best-fit-line equation obtained from Excel was y = 0.024x + 131.5 Predict where (the Vernier reading) you may find the faint purple line in Hg-lamp. which was very challenging to find in this lab. 5. Which obital (or obitals) has the lowest energy for H atom? How about O atom? a. 2s b. 3p c. 3d d.2p

Explanation / Answer

Answer:
Q3.

(i) Photons will be emitted if the transition is from to higher to lower orbit.
The lower orbit has lower energy than higer orbit and the energy difference will
be emitted in the form of photons during the transition to lower orbit.

Following transitions are from higher n to lower n value. Hence they will emit photons.
b. n =6 to n = 2
d. n = infinity to n = 1000
f. n = 2 to n=1

(ii) Rank the following transition according to the wavelength of photons emitted.
Energy of the nth orbit is given by, En = -RH*Z^2/n^2
Where RH is the Rydberg constant and Z is the atomic number

Energy emitted = Change in energy of the two orbits

b. n =6 to n = 2
Energy emitted, Eb = E6 - E2 = -RH*Z^2*(1/6^2 - 1/2^2) = -RH*Z^2*(1/36 - 1/4) = 0.22*RH*Z^2

d. n = infinity to n = 1000
Energy emitted, Ed = E6 - E2 = -RH*Z^2*(1/6^2 - 1/2^2) = -RH*Z^2*(0 - 1/1000^2) = RH*Z^2*1.0E-6

f. n = 2 to n=1
Energy emitted, Ef = E2 - E1 = -RH*Z^2*(1/2^2 - 1/1^2) = -RH*Z^2*(1/4 - 1) = 0.75*RH*Z^2

So energy emitted in increasing order is given by, Ed < Eb < Ef

Wavelength and energy are inversely related by, lambda = h*c/energy

So wavelength emitted in decreasing order is given by, Ef > Eb > Ed

Q5.
(i) Which orbital has lowest energy for H atom
Answer: (a) and (d)
Energy of H like atoms are given by, En = = -RH*Z^2/n^2.
Higher n will have more energy and less negative energy.
Lower n will have less energy.

So electrons in both 2s and 2p will have the lowest energy for H atom as hydrogen
is having only one electron.

(ii) Which orbital has lowest energy for O atom
Answer: (a)
O atom electrons occupy both the 2s and 2p orbitals.
The electrons in s orbital has lower energy than p orbital.

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