Unraveling the Mystery of Neutral Atoms and Electric Fields

[MHD93]

Hi

People all know that a neutral atom has no net charge.

Well, does that mean that it neither creates an electric field nor is affected by any electric field?

I wonder whether it's correct or not, because the distance between a test charge outside this atom is closer to its electrons relative to its protons.

Thanks

 

[ZapperZ]

Hi

People all know that a neutral atom has no net charge.

Well, does that mean that it neither creates an electric field nor is affected by any electric field?

I wonder whether it's correct or not, because the distance between a test charge outside this atom is closer to its electrons relative to its protons.

Thanks

There are two aspects to answering your question. The first is classical, and the second is quantum mechanical, or if you prefer, chemistry.

1. Tackle this using classical E&M. Put a charge Q at an origin. Now, on a spherical shell at a radius R, put an amount of charge -Q that is spherically symmetric about the origin.

Using Gauss's Law, what is the E field at a field point r>R?

2. An electric field doesn't affect an atom in ways that it changes its path or anything similar to a charged particle. However, it can change it internal "structure", such as its energy levels. The Stark effect is one clear example. At some point, with sufficiently high E field one can also induce an electric dipole by shifting the orbital geometry with respect to the nucleus, etc. So yes, an electric field can affect a neutral atom, but not in the same way you may have in mind.

Zz.