Question Video: Identifying the Ground State for an Atom with Two Electrons | Nagwa Question Video: Identifying the Ground State for an Atom with Two Electrons | Nagwa

# Question Video: Identifying the Ground State for an Atom with Two Electrons Science • First Year of Preparatory School

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Which of the diagrams shows the ground state for an atom that contains two electrons? [A] Diagram A [B] Diagram B [C] Diagram C [D] Diagram D [E] Diagram E

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### Video Transcript

Which of the diagrams shows the ground state for an atom that contains two electrons?

Electrons in an atom occupy energy levels. Energy levels are regions around the nucleus in which electrons move according to their energies. The energy level closest to the nucleus in an atom is the K energy level. The second energy level is the L energy level. The third energy level is the M energy level. And the fourth is the N energy level. With this information, we can eliminate answer choices (D) and (E) as the energy levels are not labeled correctly. Let’s remove these answer choices from the screen to finish discussing the question.

We are told that the atom in the question is in the ground state. The ground state is the lowest possible energy state of an atom. The ground state is achieved when all of the electrons in an atom are in the lowest possible energy levels. Of the four energy levels shown, the energy level with the lowest energy is energy level K. The energy levels increase in energy the farther they are from the nucleus. So we should expect that for an atom to be in the ground state, the electrons should fill the K energy level first, followed by L then M then N.

We now know the order in which the electrons will fill the energy levels. But we need to know how many electrons each energy level can hold. The K energy level can contain a maximum of two electrons. The L energy level can hold up to eight, M up to 18, and N up to 32. The atom in the question, which is in the ground state, contains two electrons. The first electron will occupy the lowest energy level, level K. The second electron will also be found in the K energy level, as this energy level can hold up to two electrons. So an atom that contains two electrons will be in the ground state when both of those electrons occupy the K energy level. This is represented by the diagram shown in answer choice (C).

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