لیزر در سه مرحله

Here is a classic interpretation of what the atom looks like:

An atom, in the simplest model,
consists of a nucleus and orbiting electrons.

This simple atom consists of a nucleus (containing the protons and neutrons) and an electron cloud. It’s helpful to think of the electrons in this cloud circling the nucleus in many different orbits.

An iron atom and its four unpaired electrons
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