For the isoelectronic series S2-, Cl-, Ar, K+, and Sc3+, which species requires the least energy to remove an outer electron?

thanks

They all have the same number of electrons (40) in the same shell arrangements, but S(2-) has the least nuclear charge. That should be a clue. Furthermore, doubly negative ions (with two extra electrons) tend to be quite unstable.

That number of electrons I wrote should be 18, not 40.

oh, that clears it up a bit, thanks!

No problem! I apologize for the mistake in my previous response. To correct it, the isoelectronic series S2-, Cl-, Ar, K+, and Sc3+ all have the same number of electrons (18) in the same shell arrangements. Among these species, S2- requires the least energy to remove an outer electron. This is because S2- has the greatest electron-electron repulsion due to its extra two electrons, which weakens the attraction between the nucleus and the outermost electron. As a result, it is easier to remove an outer electron from S2- compared to the other species in the series.

To determine which species requires the least energy to remove an outer electron in the given isoelectronic series, we need to consider a few factors.

First, we can examine the nuclear charge of each species. The nuclear charge refers to the positive charge of the nucleus, which attracts the negatively charged electrons. The greater the nuclear charge, the stronger the attraction between the nucleus and the electrons, making it more difficult to remove an electron.

In this series, S2- has the least nuclear charge due to its greater number of protons compared to the other species. This is because the extra electrons in S2- do not contribute to the nuclear charge but increase the electron-electron repulsion, resulting in a weaker attractive force. Therefore, S2- requires the least energy to remove an outer electron.

Additionally, doubly negative ions (such as S2-) tend to be more unstable compared to singly negative ions (like Cl-). The repulsion between the two extra electrons in S2- makes it easier to remove one electron, further supporting the idea that S2- requires the least energy to do so.

It is important to note that the number of electrons mentioned earlier (40) was incorrect. The correct number of electrons for this isoelectronic series is 18, which is the electron configuration for argon (Ar). This indicates that all the species in the series have the same electron configuration, but differ in their nuclear charge.

Therefore, based on the information given, S2- requires the least energy to remove an outer electron among the given species in the isoelectronic series.

sc3+