Hi all,

 

I was just curious to know two things:

 

A. What actually is an 'Isolated' atom?

 

B. How was this name given?

 

I am not sure but I think isolated atom is an atom which is inert and in ground state.

I have no idea either, I`ve never heard of it?

 

Singlet atoms and Interstitial atoms (as in the Wigner effect) I have encountered, I wonder if it could be either of these?

It may just be referring to an atom that is not interacting with any other atoms, fields or other particles (e.g. photons)

No, i am quite sure its isolated atom. here is an abstract from wikipedia:

 

"

 

Isolated atoms

Atomic physics always considers atoms in isolation - i.e. a model will consist of a single nucleus which may be surrounded by one or more bound electrons. It is not concerned with the formation of molecules (although much of the physics is identical) nor does it examine atoms in a solid state as condensed matter. It is concerned with processes such as ionization and excitation by photons or collisions with atomic particles.

 

While modelling atoms in isolation may not seem realistic, if one considers atoms in a gas or plasma then the time-scales for atom-atom interactions are huge in comparison to the atomic processes that we are concerned with. This means that the individual atoms can be treated as if each were in isolation because for the vast majority of the time they are. By this consideration atomic physics provides the underlying theory in plasma physics and atmospheric physics even though both deal with huge numbers of atoms.

 

Additionally, the properties of an atom in isolation is different from that of individual atoms in relatively close proximity to each other. This is because medium and long range forces come into play with proximity. "

 

can some1 explain now Please, i can't still get it in my head.

Sounds to me like an "isolated atom" is just a subjectively attributed ideal state that some people use to make modelling of atoms simpler, and that in the real world, atoms ARE acted upon by other atoms and forces, so are never really isolated. It's just that sometimes it's treated as "isolated" to make thought experiments and modelling easier.

 

 

That's just how I interpreted your wiki quote above. This is not necessarily what it means. All the best.

The quote is basically as I described it above. It's an idealization of no external influences.

 

As an example with which I am quite familiar, the second is defined as 9192631770 oscillations of the hyperfine states of an isolated cesium-133 atom. That's because collisions and stray electric and magnetic fields will all give rise to errors because they change the frequency.

 

So you define it for an isolated atom, and then try and quantify all of the perturbations (collision shift, Stark shift and Zeeman shift from the three examples I gave)

the second is defined as 9192631770 oscillations of the hyperfine states of an isolated cesium-133 atom. That's because collisions and stray electric and magnetic fields will all give rise to errors because they change the frequency.

 

So you define it for an isolated atom, and then try and quantify all of the perturbations (collision shift, Stark shift and Zeeman shift from the three examples I gave)

 

can I have Fries with that?

Well thank you all, I think I understand it some what now. You were a good help, all of you. thanks again!