Radius

[Lily Mohtashami]

When ions are isoelectric how do you know which has the smallest radius?

[705340227]

You can look at the number of protons. If there are more protons, the higher positive charge pulls the electrons in and makes the radius smaller.

[AntonioZarich2E]

With isoelectric ions, the ion with the smallest nuclear charge will have the biggest radius.

[Lily Mohtashami]

Oh okay that makes sense thank you.

[Mahika More 1H]

When you have more protons, the nucleus pulls on the electrons making it smaller despite possibly a larger amount of electrons. So the ion with the least protons will have the largest radius.

[Evie Li_1H]

If you need an example, Cl-, Ar, and K+ are all isoelectronic because they all have the same number of electrons as Neon (10 electrons). When an atom has more protons than neutrons, the higher the attraction between electrons and protons, so it will be smaller as the nucleus pulls the electrons in more strongly. The opposite is true for ions with more electrons than protons. So Cl- would have a larger radius than K+.

[joshtully]

Whichever ions have the most protons have the smallest ionic radius, because they pull the electrons in tighter.

[Namratha Gujje]

The more electrons that there are the smaller the radius is. The protons are tight and are pulled to the nucleus. This is opposite for electrons. If there are more electrons, or if there are free electrons then the radius will be bigger.

[George_Yin_3I]

When ions have the same electron configuration, you need to look at the proton number. A greater proton number means a greater effective nuclear charge, and therefore smaller ionic radius.