Question Video: Identifying the Energy Level Diagram for an Oxygen Ion | Nagwa Question Video: Identifying the Energy Level Diagram for an Oxygen Ion | Nagwa

Question Video: Identifying the Energy Level Diagram for an Oxygen Ion Science • First Year of Preparatory School

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Which of the following represents the correct filling of electrons in the energy levels of an oxygen ion O²⁻? [A] Option A [B] Option B [C] Option C [D] Option D [E] Option E

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Video Transcript

Which of the following represents the correct filling of electrons in the energy levels of an oxygen ion O2−?

We’ve been given five energy level diagrams labeled from (A) to (E). Each energy level diagram shows the electronic configuration for each atom or ion. The electronic configuration is the distribution of electrons in energy levels. So, how do electrons distribute themselves in energy levels? Electrons fill energy level K first. Once K is full, the remaining electrons fill energy level L. They then fill energy levels M and N in turn. Each energy level holds a different maximum number of electrons. The first level can hold a maximum of two electrons. The second, third, and fourth energy levels hold a maximum of eight, 18, and 32 electrons, respectively.

Now that we know how electrons fill energy levels, we need to know how many electrons are in an O2− ion. The symbol for oxygen tells us that a neutral atom has eight electrons. But we want to know the number of electrons in an oxygen ion. The charge indicates that an oxygen ion contains two more negatively charged electrons than an oxygen atom. Thus, in total, an oxygen ion contains 10 electrons. The first two of the 10 electrons fill energy level K. The remaining eight electrons fill energy level L. Thus, the electronic configuration is 2,8. And the energy level diagram which represents the correct filling of electrons in the energy levels of an oxygen ion O2− is (B).

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