Question Video: Deducing the Energy Level Diagram Representing the Change from a Sulfur Atom to a Sulfur Ion Science

Which of the energy levels shows the change in electronic configuration from a sulfur atom (32 S 16) to a sulfur 2− ion?


Video Transcript

Which of the energy levels below shows the change in electronic configuration from a sulfur atom, 32 S 16, to a sulfur two minus ion?

In this question, we are told that a neutral sulfur atom changes to a negative sulfur ion. To determine the way the electronic configuration of sulfur would change, we must understand the formation of a negative ion. Generally, when a negative ion is formed, a nonmetal atom gains electrons. This occurs so that the nonmetal atom will attain the electronic configuration of a noble gas. All of the diagrams given in the answer choices show the positively charged center of the atom called the nucleus. Then, they illustrate the energy levels ordinarily found outside of the nucleus. These energy levels are ordered using capital letters. The numbers written on the bottom of the diagrams show the amount of electrons present in each energy shell. The sulfur atom will gain electrons to achieve a noble gas configuration.

Let’s have a look at some electronic configurations of noble gases.

Helium, atomic number two, will have two electrons in energy level K. Neon, atomic number 10, will have two electrons in the K level and eight electrons in the L level. Argon, atomic number 18, will have two electrons in K, eight electrons in L, and eight electrons in level M. Let’s keep these in mind as we have a look now at sulfur.

We’ll start by comparing the atom diagrams to the electronic configuration for a neutral sulfur atom. We are given the symbol for sulfur in the question. The bottom left number in the symbol represents the atomic number of sulfur. The atomic number tells us the number of protons a sulfur atom contains in its nucleus. As a neutral atom, sulfur will also contain the same number of electrons. Therefore, a sulfur atom will have a total of 16 electrons.

Energy level K will hold the first two electrons. The next energy level L will hold the next eight electrons in the sulfur atom. With only six electrons remaining, they will all be found in energy level M. Let’s compare this to the diagrams given for the sulfur atom in the answer choices. We can see that answer choices (A) and (C) do not have the correct configurations for a sulfur atom, so we can eliminate them.

Let’s now deduce how the diagram of a sulfur two minus ion would look.

We are told the charge of the sulfur ion will be two minus, so we know it will have two more electrons than protons. When we add 16 and two, we get 18. A neutral sulfur atom with 16 electrons has 6 electrons in the M energy level. With two more, it will have eight, giving it a two minus charge. The sulfur ion achieves the noble gas electronic configuration of argon. Let’s have a look at the remaining ion energy level diagrams.

We can see that answer choice (D) matches the correct energy level diagrams for both the neutral sulfur atom and the negative sulfur ion. Therefore, the energy levels that show the change in electronic configuration from a sulfur atom to a sulfur two minus ion is answer choice (D).

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