Posted by **Brenda** on Saturday, January 19, 2013 at 7:13pm.

a.) Caculate the energy of light emitted when an electron moves from n=2 to n=1 in the hydrogen atom.

b.) Caculate the energy of light emitted when an electron moves from n=4 to n=2 in the hydrogen atom.

c.) How many total different light energies can be emitted from an electron moving down from n=5?

I don't know the equation for a.) and b.), and I don't understand c.). Help please!

- Chemistry -
**DrBob222**, Saturday, January 19, 2013 at 7:38pm
E= 2.180E-18(1/n^2(1) - 1/n^2(2))

R = 1.09737E7

n1 = 1 so n^2 = 1

n2 = 2 so n^2 = 1/2^2 = 1/4

For b the only difference is

n1 = 2 so n^2 = 4

n2 = 4 so n^2 = 16

For c draw a diagram of energy levels that will look something like this.

n = 5 -----------------

n = 4 ----------------

n = 3 ---------------

n = 2 ---------------

n = 1 --------------

So an electron can move from

5 to 4;

5 to 3;

5 to 2;

5 to 1 and this results in 4 different energies being emitted.

After the 5 to 4, then the 4 can do the same thing; i.e.,

4 to 3;

4 to 2;

4 to 1; which results in 3 more energies being emitted.

Then the electron that goes from 5 to 3 can separately do

3 to 2; and

3 to 1; resulting in two more and finally, the one at 2 can do

2 to 1 resulting in 1 more. Add those together for the total. If I could draw a diagram on this site I could explain it much better.

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