Ground state vs. excited state

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Johana Jeon 1A
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Joined: Sun Feb 12, 2017 3:00 am

Ground state vs. excited state

Postby Johana Jeon 1A » Sat Jul 08, 2017 4:34 pm

What does it mean for an electron configuration to represent a ground state or an excited state of an atom?
Is it talking about the opposite / same spin?

In 2.39: Determine whether each of the following electron configurations represents the ground state or an excited state of the atom given.

Dabin Kang 1B
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Re: Ground state vs. excited state

Postby Dabin Kang 1B » Sat Jul 08, 2017 5:24 pm

The ground state electron configuration of an element is the same as the regular configuration in which the electrons are in the lowest possible energy state. For example, the ground state electron configuration of oxygen is 1s2 2s2 2p4.

The excited state electron configuration shows when an electron is excited and jumps into a higher orbital. For example, sodium in its excited state would have an electron configuration of 1s2 2s2 2p6 3p1, compared with its ground state of 1s2 2s2 2p6 3s1.

For 2.39, I believe that a, b, and c are excited, while d is in the ground state.

Sarah_Wilen
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Re: Ground state vs. excited state

Postby Sarah_Wilen » Sat Jul 08, 2017 5:39 pm

The ground state in an atom is when electrons are in the lowest possible energy level. In this state, the electrons have the lowest potential energy.

What I mean by low potential energy is that there is nowhere for the electron to "fall". Potential energy is the energy possessed by the electron by virtue to its position relative to others. If I had a piano on a cliff, it will have high potential energy because it has the potential to fall down (potential energy converting to kinetic energy). When the piano has crashed to the ground on a cartoon character, the piano is in its "ground state" because it possesses the lowest potential energy. The piano is in the lowest position relative to its surroundings, so it is in its lowest energy state.

Like the piano on the ground, the atom in its ground state means it is in its lowest energy state. All elements on the periodic table are in their ground states.

In the question, the only configuration for a ground state atom is d. It follows the rules for electron configuration filling in the ground state...
-Aufbau's principle: electrons must fill the lowest energy shells first. (see picture attached)
-Hund's rule: when filling sub-levels, electrons must not be spin paired in the orbitals until each orbital contains one electron and no orbital can have two electrons with the same spin.
-Pauli Exclusion Principle: no two electrons can have the same quantum numbers. An orbital can only hold 0,1, or 2 electrons. The electrons must have opposite spins if there are 2 electrons in the orbital.

On the other hand, above ground states are "excited states". These are states with higher energy than the one of the ground state. If you shoot the atom with a photon, then the photon may be absorbed, so the electrons of the atom will jump from the ground state to an excited state (the difference between the two energies of the final and initial state is the energy of the photon that got absorbed). In an excited state, not all electrons are in the lowest possible energy levels.

For example, in the question, a (carbon) is not in the ground state, and it doesn't follow Hund's rule. The electrons in 2p were already spin paired in the orbital before each orbital contained one electron.

An easy way to determine if the electron is in the excited state is to compare it to its ground state. If you see electrons have been "moved" to a higher orbital before filling the lower orbital, then that atom is in an excited state.

Hope this somewhat helped!

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Johana Jeon 1A
Posts: 30
Joined: Sun Feb 12, 2017 3:00 am

Re: Ground state vs. excited state

Postby Johana Jeon 1A » Sat Jul 08, 2017 5:50 pm

Thank you guys :)


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