Question Video: Identifying the Energy Level Diagram That Represents the Electronic Configuration of the Magnesium Ion | Nagwa Question Video: Identifying the Energy Level Diagram That Represents the Electronic Configuration of the Magnesium Ion | Nagwa

# Question Video: Identifying the Energy Level Diagram That Represents the Electronic Configuration of the Magnesium Ion Science • First Year of Preparatory School

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A magnesium ion contains two fewer electrons than an atom of magnesium. If the atomic number of magnesium is 12, which of the following energy level diagrams shows the correct electronic configuration of the magnesium ion? [A] Diagram A [B] Diagram B [C] Diagram C [D] Diagram D [E] Diagram E

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### Video Transcript

A magnesium ion contains two fewer electrons than an atom of magnesium. If the atomic number of magnesium is 12, which of the following energy level diagrams shows the correct electronic configuration of the magnesium ion?

This question is asking us to identify the diagram showing the correct electronic configuration.

An electronic configuration shows the distribution of electrons in energy levels of an atom or ion. The numbers written below the energy levels indicate the amounts of electrons in those energy levels. The energy levels shown in each diagram are levels K, L, M, and N. Each different energy level holds a different maximum number of electrons. Level K can hold up to two electrons. Level L can hold up to eight. Level M can hold up to 18. And level N can hold up to 32 electrons. Electrons tend to occupy the lowest energy states, or in other words levels, as possible. So, electrons fill the lowest energy levels first before occupying higher energy levels.

We are looking for the answer choice that shows the electronic configuration of the magnesium ion. We are also told that magnesium has an atomic number of 12, which means it has 12 protons. In a neutral magnesium atom, there are also 12 electrons.

We are told that the magnesium ion contains two fewer electrons than an atom of magnesium. The correct electronic configuration will not contain 12 total electrons. Instead, to calculate the total number of electrons in the ion, we must subtract two. The magnesium ion will then have 10 total electrons in its electronic configuration. We can see that the only diagram with 10 total electrons is answer choice (B). The two electrons in the K level and the eight in the L level is a total of 10 electrons.

Therefore, the energy level diagram that shows the correct electronic configuration of the magnesium ion is answer choice (B).

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