# Principal Quantum number by size?

1. Jul 19, 2010

### physics(L)10

1. The problem statement, all variables and given/known data
What is the value of the principal quantum number for a hydrogen atom to have a size of one micron?

2. Relevant equations
r=(5.3x10-11)(n2)
r=1x10-6/2=5x10-7

3. The attempt at a solution

5x10-7=(5.3x10-11)(n2)

97.1 = n

How is this possible? lol Maybe it's more complicated then I'm thinking.

2. Jul 19, 2010

### Redbelly98

Staff Emeritus
Just use the nearest integer value.

3. Jul 19, 2010

### physics(L)10

So I'm right? The answer is just 97? I thought the principal quantum numbers (n) only go up to like 5 or 6 or something like that though.

4. Jul 19, 2010

### Redbelly98

Staff Emeritus
Yes, you're right. n can go up to infinity in theory. In practice, an atom with such a high n would eventually collide with another atom or perhaps a container wall, and completely lose the electron.

5. Jul 20, 2010

### physics(L)10

Alrighty, thank you very much :)