Photons may be generated by the transition of an electron from one energy level in an atom or molecule to a lower energy level. Photons may be absorbed as they cause an electron to be raised from a lower energy level to a higher energy level (in an atom or molecule).
The photon itself does not undergo a transition of energy: it either exists (with an energy defined by its wavelength), or it doesn't exist (it was destroyed!). You could say that the emitting or absorbing atom/molecule/etc. undergoes a change, or transition, in energy. But "transition" is usually used as a name for the process of jumping in energy.
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2s2 2p4 is the valence electron configuration for oxygen
The answer is in scientific notation 34^67 42’063 1220.
The correct form for scientific notation is a x 10^b. where a is a number or decimal such that the absolute value of a is greater than or equal to 1 and less than 10, or 1 ≤ |a|. < 10. b is the power of 10 required to make the scientific notation mathematically equivalent to the original number.
To write this number in scientific notation, you must first shift the number of decimal places from the original number by 4 places between 4 and 2. We're subtracting from the exponent because we're shifting the decimal four places to the right.
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The question is incomplete, complete question is :
Determine the pH of an HF solution of each of the following concentrations. In which cases can you not make the simplifying assumption that x is small? (
for HF is
.)
[HF] = 0.280 M
Express your answer to two decimal places.
Answer:
The pH of an 0.280 M HF solution is 1.87.
Explanation:3
Initial concentration if HF = c = 0.280 M
Dissociation constant of the HF = 

Initially
c 0 0
At equilibrium :
(c-x) x x
The expression of disassociation constant is given as:
![K_a=\frac{[H^+][F^-]}{[HF]}](https://tex.z-dn.net/?f=K_a%3D%5Cfrac%7B%5BH%5E%2B%5D%5BF%5E-%5D%7D%7B%5BHF%5D%7D)


Solving for x, we get:
x = 0.01346 M
So, the concentration of hydrogen ion at equilibrium is :
![[H^+]=x=0.01346 M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3Dx%3D0.01346%20M)
The pH of the solution is ;
![pH=-\log[H^+]=-\log[0.01346 M]=1.87](https://tex.z-dn.net/?f=pH%3D-%5Clog%5BH%5E%2B%5D%3D-%5Clog%5B0.01346%20M%5D%3D1.87)
The pH of an 0.280 M HF solution is 1.87.