# Electron orbit question

1. May 22, 2013

### mia5

Why are the electrons so far away from the nucleus of an atom ?

2. May 22, 2013

One time Ernst Rutherford said that that the rotation of electrons around the nucleus like the rotation of the planets around the sun , so the attraction force that made the planets rotate around the sun but wasn't enough to make these planets stick to the sun due to the centrifugal force . The same in the atom , there is an equality between the attractive force and the centrifugal force ( because the nucleus is positive and the electrons are negative )

3. May 22, 2013

### ZapperZ

Staff Emeritus
What do you consider to be "so far away"? I'd say that a few Angstroms as not be far away at all!

Zz.

4. May 22, 2013

### technician

The distance from the nucleus to the electron ( in this basic picture of atoms !!) is about 10^5 times the size of the nucleus. Would you not call this 'far away' relatively speaking?

5. May 22, 2013

### ZapperZ

Staff Emeritus
Nope, because:

1. I could consider that it is the nucleus that is too small, rather than the electron being too far away,

2. The electron actually DOES get quite close to the nucleus. Look at the spread in position for the 1s orbital, for example.

Zz.

6. May 22, 2013

### technician

Is the Earth far away from the Sun because the Sun is 'too small'?

7. May 22, 2013

### ModusPwnd

The sun isnt far away. Its by far the closest star to the earth there is. Its so close that it appears as a disk rather than a point in the sky. :tongue:

8. May 22, 2013

### ZapperZ

Staff Emeritus
You obviously miss the whole point of my question to the OP and my reply to you. A question that is simply based on "is it too far away" is subjective! I illustrated that by countering that it could be too small. Who is to say which is "correct"? This then renders the question simply a matter of personal taste, rather than based on physics.

I noticed to neglected the second part of my response, which actually HAS a physics content.

Zz.

9. May 22, 2013

OP could be speaking relatively.If someone enlarges an atom to the size of the earth, the electron should be much far away than the moon

10. May 23, 2013

### sophiecentaur

The reason for the spacings inside an atom are based on Quantum Mechanics, I think. The wave nature of the bound electron gives a minimum likely distance for it to be found 'in orbit' (the probability density function).

11. May 23, 2013

### Staff: Mentor

The electron is light (as in: not heavy) relative to the nucleons, and the electromagnetic interaction is weak. Both effects lead to large expectation values for the distance, and both have no known deeper reason.

12. May 23, 2013

### BruceW

yeah. It is (loosely speaking) because the electromagnetic coupling constant is much smaller than the coupling constant of the strong force. Also, as mfb said, the mass of the electron is smaller than the mass of the nucleons.