[jamesmith134]

Hello,

I just got a question, to determine which of the given excited states is true but I don't know how to do that:
The 3 options are :

a)  [Ne]3s(2)3p(5)4s(1)
b)  [Xe]4f(14)5d(10)6s(2)6p(4)
c)  [Ar]3d(1)4s(2)

How do I know which is the currect to describe an excited state (Also which atom does each of them describe?  )

The number in ( ) is the number of electrons I just couldn't write it as a power symbol, I hope you understand

Thanks

[johnnyjohn993]

Those who are in the ground state are said to be NOT in their existed STATE. The ground state is said to be isoelectronic(or filled all its outer orbital depending on your azimuthal quantum number) with the noble gases. we tend to look at the highest principal quantum and their filled shells.

a) we see that 4s¹ is the highest principal quantum number, we know that the "s" orbital can carry 2electrons but in this case its is only one. there for it isn't in the ground state. which means its in the excited state.

b) the same goes here, 6p has only 4 electrons(instead of 6) on its shells therefore it is in the excited state.

c) this is given states is in the ground state. because of the 4s has filled its orbital with 2electrons

[mjc123]

I'm afraid this is all quite wrong. A ground state is not isoelectronic with the noble gases (unless the atom happens to be a noble gas or an ion like Na⁺). An atom has a certain number of electrons - the same as its atomic number - which is usually not the same as a noble gas. The ground state is the lowest energy configuration of these electrons, which may not have a complete outer shell; for example the ground state of K is [Ar]4s¹. If electrons are promoted to a higher level, leaving a lower level incompletely filled, that is an excited state.
Are you familiar with the Aufbau principle? That you fill up the energy levels in order, beginning with the lowest. If the highest level is incompletely filled, simply because of the number of electrons available, that does not make it an excited state. Also, the order of energy levels is not always that of the principal quantum number, e.g. in first-row transition metals 4s is lower than 3d and fills up first. See http://en.wikipedia.org/wiki/Aufbau_principle.
In example a) you have an electron in 4s, while 3p is incompletely filled. Is this a ground state?
In b) 4f, 5d and 6s are filled, then you have 4 6p electrons. Is this a ground state?
In c) you have a filled 4s and a 3d electron. Remember the point about the order of levels.

Also which atom does each of them describe?

Come on, you can do this. Just count the electrons.

[asmcriminal]

Well it helps if you put them in order, I know difference people write them in different ways, but I always put the orbitals in order as i go across the periodic table.

[Ne] 3s²,3p⁵,4s¹
[Xe] 6s²,5d¹⁰,4f¹⁴,6p⁴
[Ar] 4s²,3d¹

Notice how the [Ne] based atom "skips" the 3p⁶.There are no electrons there, it "jumps" a electron location. This is because it's in an excited state.