Ground state atoms

[Jiller1994]

"Which of the following has an unpaired electron in its ground-state electronic configuration:
Ne, Ca+, Na+, O2-"

My thinking:
Ground state simply means no charge and then setting up electron config quickly
So: Ne is noble gas; no unpaired e-
Ca+ becomes [Ar]4s2
Na becomes [Ne] 3s1
O becomes ...2p4
So there are 2 that have unpaired electrons but answer I'm not expecting is Ca "has a ground state of [Ar]4s1".
Uhhh? Any explanations

---

Members don't see this ad.

 

[Quinoline]

The + next to the Ca means that is is missing one electron, so instead of the [Ar]4s2 configuration of Ca, it has the [Ar]4s1 since it is Ca+. If it was Ca2+ it would have [Ar].

 

[Jiller1994]

The + next to the Ca means that is is missing one electron, so instead of the [Ar]4s2 configuration of Ca, it has the [Ar]4s1 since it is Ca+. If it was Ca2+ it would have [Ar].

Doesn't ground state, however, refer to an atom with NO charge- it's most stable, low energy state

 

[Quinoline]

Doesn't ground state, however, refer to an atom with NO charge- it's most stable, low energy state

The definition for ground state that I learned was the lowest energy state of a given atom, so for the most part putting the electrons in the lowest energy orbitals. Non-ground state / excited state would be having an electron in a higher energy state than it could be, for example Mg having an electron in 3p instead of 3s. I think ground state is just the normal electron configuration we think of. It would seem very weird to me if the question is asking you to ignore the charges given in the question statement.

 

[chemist16]

Doesn't ground state, however, refer to an atom with NO charge- it's most stable, low energy state

It's not asking you for the ground state of an atom. It's asking you for the ground state of the substances listed, three of which are ions. Ground state simply refers to a non-excited electronic, vibrational, and rotational state (in practice, we only worry about the electronic state). So Ne has a full valence shell, Ca+ has one valence electron, Na+ has zero valence electrons, and O2- also has a full valence shell. So the only one with an unpaired electron is Ca+.

You're simply confusing "ground state" with the term "elemental." The ground state electronic configuration of Na+ is not the same as the ground electronic configuration of Na. Just draw your orbitals and start filling them to understand.