HERE GOES THE QUESTION
✏️Calculate the energy for Li^+2 atom for 2nf excited state.
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Answers
Since Lithium 2+ (atomic number Z = 3) and Hydrogen (atomic number Z = 1) both have one electron, you can use the Rydberg equation for the atomic energy levels:
E(n; Z) = -R*(Z^2)/(n^2),
The first excited state of hydrogen is n = 2 (n = 1 is the lowerst-energy, or "ground" state), which from the Rydberg equation has an energy equal to E(n = 2; Z = 1) = -R/4 = -3.4 eV.
The states of Lithium 2+ have energies equal to E(n, Z = 3) = -9R/(n^2). To solve for n (which tells us what excited state the ion is in), we need to equate the hydrogen first-excited state energy with this energy:
-R/4 = -9R/(n^2)
Solving for n gives:
n = sqrt(9 x 4) = sqrt(36) = 6
n = 6 (fifth excited) state of Li 2+ has the same energy as the n = 2 (first excited) state of hydrogen, according to the Rydberg equation for hydrogen-like (one-electron) atoms.
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