Question

How many orbitals do you think exist in a atom?

Answer 1

As many as it needs.

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Orbitals are made of electrons. When we talk about orbitals, it's just a nice way to say that electrons are in certain energy states. It's not like orbitals exist if electrons are not in those energy levels.

So you can think of it as follows:

The orbitals that are used exist because the electrons in the atom occupy that energy level. Otherwise, the orbital doesn't exist.

Thus,

• core orbitals and valence orbitals always exist.
• energy states that are empty (what we call "virtual orbitals" or "external orbitals") correspond to nonexistent orbitals, and we don't need to consider them.