usually it is the second to third layer of electrons. it depends on what atom ur talking about, some atoms (like magnesium) have 3 electron levels; when some atoms (like gold) may have over 7 levels of electrons. it sometimes has to do with the atomic number
nucleus
Scientists think that atoms basically look like an electron cloud circling a small, very dense nucleus. The electron cloud is negatively charged, makes up most of the volume of the atom, and has hardly any mass, but the nucleus is positively charged, very small, and contains all of the mass of the atom.
The electron cloud or electron shell
a cold, dense gas cloud.
The answer to that would be: An Electron Cloud Model
the electron cloud is least dense where the probability of finding an electron is LOWEST
nucleus
The nucleus is the most dense part of an atom.
The electron cloud is probably the least dense part of an atom. The electron is certainly the smallest individual component of an atom, but electrons are in motion. And because they are in motion, they describe the volume of the atom. Additionally, they describe a huge volume compared to their size. That translates into the electron cloud "taking up lots and lots of room" but being populated by only a few electrons. The electron cloud has a very, very low density.
Speaking very generally, most atoms consist of a dense nucleus which contains protons and neutrons, and an electron cloud away from the nucleus which contains electrons.
Scientists think that atoms basically look like an electron cloud circling a small, very dense nucleus. The electron cloud is negatively charged, makes up most of the volume of the atom, and has hardly any mass, but the nucleus is positively charged, very small, and contains all of the mass of the atom.
The electron cloud or electron shell
An electron cloud is an atomic orbital.
Cloud...
Cloud...
a cold, dense gas cloud.
An electron cloud is a visual model of the most likely locations for electrons in an atom.