Question Video: Determining the Number of Unpaired Electrons in an Atom of Aluminum Chemistry • 10th Grade

How many unpaired electrons are there in the ground state electronic configuration of an atom of aluminum?

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Video Transcript

How many unpaired electrons are there in the ground state electronic configuration of an atom of aluminum?

First off, an electronic configuration is the representation of the arrangement of electrons distributed among the orbitals and subshells, with the ground state electronic configuration of an atom showing the arrangement of electrons in the lowest energy levels. A typical graphical representation of the ground state electronic configuration of an atom is where the orbitals within a subshell are drawn as boxes in order from lowest to highest energy and use arrows to show how many electrons there are in each orbital, with the up or down direction of the arrow indicating the spin of the electron.

Now that we know how we will represent the arrangement of electrons in aluminum, let’s take a look at the total number of electrons an atom of aluminum has. Locating aluminum on the periodic table, we can see its atomic number is 13, which by definition means it has 13 protons. Since the question states we are looking at an atom of aluminum, this means the number of protons is equal to the number of electrons. As a result, an atom of aluminum has a total of 13 electrons in its ground state.

Now that we know the total number of electrons in an atom of aluminum, we can determine how many unpaired electrons there are in its ground state electronic configuration by remembering one main rule. This is known as the Aufbau principle, which states that electrons will occupy the lowest-energy orbitals before filling the higher-energy orbitals. That being said, the order of filling energy orbitals can be remembered using this condensed version of the Aufbau energy diagram. We can demonstrate this by drawing diagonal arrows starting with electrons filling the 1s orbital first, followed by the 2s orbital, with the filling of the 2p orbitals next in line and the 3s orbital after that. This pattern is continued down the line until all of the electrons have been accounted for.

Since aluminum has 13 electrons in its ground state, the correct graphical representation of its ground state electronic configuration will demonstrate a filled 1s, 2s, 2p, and 3s orbitals, followed by one electron in the 3p subshell. We can see that the electrons in the 1s, 2s, 2p, and 3s orbitals are all filled. And therefore all of the electrons in those orbitals are paired up. This leaves one unpaired electron in one of the 3p orbitals, which turns out to be the only unpaired electron for an atom of aluminum in the ground state.

Therefore, how many unpaired electrons are there in the ground state electronic configuration of an atom of aluminum? The answer is one unpaired electron.