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Question Video: Predicting the Group an Element Belongs to Given Its Electron Configuration in Condensed Notat Chemistry • 10th Grade

A recently discovered element has a predicted electron configuration of brackets [Rn]5f¹⁴6d¹⁰7s²7p³. In what group of the periodic table would this element likely be found?

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Video Transcript

A recently discovered element has a predicted electron configuration of brackets Rn 5f14 6d10 7s2 7p3. In what group of the periodic table would this element likely be found?

The electron or electronic configuration of an atom describes how many electrons the atom has, as well as how these electrons are arranged into different electron shells and subshells. When writing the electron configuration, electron subshells use a letter code, s, p, d, or f, to indicate the type of atomic orbitals they contain.

The periodic table can be divided into blocks that represent these subshells. Elements found in the same block have valence electrons in the same type of subshell. For example, elements found in the p block, which are the elements found in groups 13 through 18, excluding helium, have one or more valence electrons found in the p subshell. It’s helpful to remember that excluding the elements found in the d and f blocks, the period that an element is found in represents the outermost or valence electron shell. The order in which electrons fill up the various subshells in an atom is based on increasing energy. This rule is known as the Aufbau principle.

While it’s helpful to know that the subshell blocks shown in the periodic table here are organized from lowest to highest energy, the following diagram shows the relative energy values of the electron subshells. The electron configuration provided in this problem is given in a shorthand form called condensed notation. In this notation, the chemical symbol of the noble gas above the period that the element is in is written inside brackets. The remaining subshells are written after this. Rn or radon is in the 6p subshell block. The next lowest energy subshell is 7s, which holds two electrons.

If we look very carefully at the diagram on the right, we see that the next lowest subshell is 5f. This is a little more difficult to see on the periodic table because the f blocks of periods six and seven are pulled out below the table. The next lowest energy subshell is 6d, which holds 10 electrons. And finally, we reach the 7p subshell.

The two forms of the electron configuration that we’ve written are both accepted by chemists. The first one puts the subshells in order by principal quantum number or n. The second one adheres to the Aufbau principle and puts the subshells in order of increasing energy. However, in both forms, it’s the subshell that’s written last that helps us determine the group that the element is in. All p subshells hold a maximum of six electrons. This element has three electrons in its 7p subshell. Therefore, it is the third element in the 7p subshell block. Now, we can see that this element is in group 15.

In what group of the periodic table is the recently discovered element likely to be found? The answer is group 15.

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