The excited state electron configuration of one atom shows the promo of a valence electron to a higher energy state.

You are watching: Which is the electron configuration of an atom in the excited state


An electron configuration representing an atom in the excited state will show a valence electron supported to a higher energy level.

ExampleThe ground state electron configuration of salt is #"1s"^2"2s"^2"2p"^6"3s"^1#.

In the excited state, the valence electron in the #"3s"# sublevel is advocated to the #"3p"# sublevel, providing the electron configuration as#"1s"^2"2s"^2"2p"^6"3p"^1#.

This is a an extremely unstable condition and also the excited electron will drop ago down to the #"3s"# sublevel, publication the exact same amount of energy that to be absorbed, and also producing a characteristic shade of light, in this situation yellow.


Answer connect
*

Truong-Son N.
january 14, 2016

The an initial excited state is the exact same configuration together the ground state, other than for the position of one electron.

As an example, salt goes through a #3s -> 3p# transition.

The ground state electron construction for salt is:

#color(blue)(1s^2 2s^2 2p^6 3s^1)#

And the first excited state electron configuration for sodium is:

#color(blue)(1s^2 2s^2 2p^6 3p^1)#

This corresponds to an excitation to a an initial excited state the is less stable; that then leads to a relaxation back down come the floor state. The be safe emits yellow light (#"589 nm"#).

I end up going through an option rules (which aid you predict even if it is an electronic change is allowed or forbidden), term symbols, and predicting transitions. That overall tells you how I understand that a #3s -> 3p# transition is a real change for sodium.

(If you want, you have the right to skip the term icons contextual section; it"s optional.)

You may or may not have actually learned selection rules yet, however they aren"t too complicated to take note of. Castle would assist you determine exactly how to write electron configurations for excited states.

SELECTION RULES

The choice rules govern exactly how an electron is it was observed to change (excite upwards or relax downwards) from one orbital to another.

Formally, they room written as:

#color(blue)(DeltaS = 0)##color(blue)(DeltaL = 0, pm1)#

#color(blue)(L + S = J)#

#:. Color(blue)(DeltaJ = 0, pm1)#

where #DeltaS# is the readjust in intrinsic angular momentum of the electron (spin multiplicity is #2S + 1#), #DeltaL# is the readjust in orbital angular momentum, and #DeltaJ# is the change in the total angular momentum.

It is helpful to understand the selection rules if you want to predict exactly how an excited state configuration have the right to be composed just based on the atom"s (correct) ground state configuration.

EXAMPLES OF digital EXCITATION TRANSITIONS

Allowed:

An instance of an allowed electronic transition upwards of one unpaired electron to an empty orbital:

#color(green)(2s -> 2p)# (#color(green)(DeltaS = 0#, #color(green)(DeltaL = +1)#, #color(green)(DeltaJ = 0, pm1)#)

#DeltaL = +1# due to the fact that for #s#, #l = 0#, and for #p#, #l = 1#. Thus, #DeltaL = +1#.

#DeltaS = 0# due to the fact that the electron didn"t gain paired with any brand-new electron. It started out unpaired, and also it stayed unpaired (#m_s^"new" = m_s^"old"#), so #DeltaS = m_s^"new" - m_s^"old" = 0#.

Forbidden:

An example of a forbidden electronic transition upwards that one unpaired electron come an empty orbital:

#color(green)(3s -> 3d)# (#color(green)(DeltaS = 0)#, #color(green)(DeltaL = color(red)(+2))#, #color(green)(DeltaJ = 0, pm1, color(red)(pm2))#)

#DeltaL = +2# because for #s#, #l = 0#, and for #d#, #l = 2#. Thus, #DeltaL = +2#, which is bigger than is allowed, so it is forbidden.

#DeltaS# is still #0# since it"s the exact same electron transitioning together before, just towards a different orbital.

TERM signs / CONTEXT

"I"ve never seen #L#, #S#, or #J# before. Huh? What room they offered for?"

You have the right to read much more about lock here:http://snucongo.org/scratchpad/3616fa1583309e7c0ed2

DISCLAIMER: The above link explains term signs for context. It helps to know this, however you don"t have to know this favor the back of your hand unless you room taking physical Chemistry.

APPLICATION the THE choice RULES

Alright, so let"s use the selection rules themselves. Ns gave instances already, therefore let"s job-related off of the allowed transition example and adjust it a small bit. The values for #L#, #S#, and #J# space pretty similar.

Let us examine this energy level diagram for sodium:

*

You have the right to see present on the diagram going from the #3s# orbital to two #3p# orbital destinations. That shows either an excitation from the #3s# to the #3p# or a relaxation native the #3p# come the #3s#.

These two lines are marked #589.6# and also #589.0#, respectively, in #"nm"#, so what you view happening is the sodium provides its #"589 nm"# excitation change (upwards), and also then relaxes (downwards) come emit yellow light.

See more: Can You Potty Train A Tortoise To Use A Litter Box? Can You Train A Tortoise To Use A Litter Box

Therefore, a usual excitation/relaxation transition sodium renders is:

Excitation Transition: #3s -> 3p# (#DeltaS = 0#, #DeltaL = +1#, #DeltaJ = 0, +1#)

Relaxation Transition: #3p -> 3s# (#DeltaS = 0#, #DeltaL = -1#, #DeltaJ = 0, -1#)

(Term symbol notation:

#""^2 S_"1/2" -> ""^2 P_"1/2", ""^2 P_"3/2"#, excitation

#""^2 P_"1/2", ""^2 P_"3/2" -> ""^2 S_"1/2"#, relaxation)

So the ground state electron configuration for salt is:

#color(blue)(1s^2 2s^2 2p^6 3s^1)#

And the first excited state electron configuration for sodium is:

#color(blue)(1s^2 2s^2 2p^6 3p^1)#

Lastly, one easy method to mental what transitions are permitted is to note that electronic transitions on power level diagrams room diagonal, and involves surrounding columns.