atomic radius

[Kaylee Nezwek 1D]

does anyone know how to determine if Cl- or K+ is bigger? if so, could you please walk me through :)

[Adrienne Chan 1G]

Cl- has 17 protons, whereas K+ has 19 protons. However, they have the same number of electrons. This means that K+ has a greater effective nuclear charge and will pull on the electrons more tightly than Cl-, making its atomic radius smaller. Hope this helps!

[Zoe Staggs 3B]

Since K+ and Cl- occupy the same outermost shell, whichever ion with a greater proportion of protons to electrons will be smaller. Therefore Cl- is the larger ion of the two.

[Jose Miguel Conste 3H]

Cl- is bigger because of the extra electron, that extra electron allows for more push from protons making the atomic radius larger

[Grace_Remphrey_2J]

Both ions have their outermost electrons located on the same energy level, but they do not have the same ionic radius. The number of protons each species has in its nucleus varies. Potassium, which has an atomic number equal to 19, has 19 protons in its nucleus. Chlorine has 17. In the case of the potassium atom, the outermost electrons will be attracted by the nucleus more. K+ has a bigger effective nuclear charge than Cl−, which translates to a bigger net positive charge felt by the outermost electrons. This will compress the energy levels a bit and make the ionic radius smaller for the potassium cation. Therefore, the chloride anion will have a larger atomic radius.

[Simrah_Ahmed1J]

When you are comparing 2 ions that have the same electron configuration, you are obviously not considering the energy level as a factor in ionic/atomic radius because they have the same electron configuration. So then you can think about it in terms of "pulling power" or attraction of the nucleus. So you know that, in this case, K⁺ has a higher atomic number, so therefore it has a higher amount of protons in its nucleus, which therefore attract its electrons more strongly, pulling them more closer into the nucleus. Whereas K⁺ has 19 protons, Cl^- only has 17. This is why the ionic radius of Cl^- will be larger.

[Hailey Qasawadish 2J]

You have to look at this question from the point of effective nuclear charge. Cl- is bigger because of the extra electron.

[Colin Squire 3B]

The K+ ion will be smaller than the Cl- ion because of the fact that it can pull the electrons in closer because of its + charge.