Ionic radius

[RJ Lopez 2l]

How do we determine ionic radius? for example, how would you find cl- or p3-

[Preston Pham 2H]

We determine the ionic radius by looking at the periodic table. First, you need to know the trends for ionic radius. Ionic radius increases as you move down a column or group. This makes sense because as you go down each row adds a new electron shell. Ionic radius decreases moving from left to right because as you move more to the right there are more protons which brings the electrons closer to the nucleus thus making the ionic radius decrease. For Cl- and P3-, Cl is smaller than P because it has more protons than P and thus has a smaller ionic radius.

[Bruce Ruff 2B]

Anions like Cl- or P3- are generally larger than their neutral atoms. This is because gaining electrons makes the pull per electron to the nucleus slightly weaker, causing an increase in the ionic radius. The rule generally goes that (cation < neutral atom < anion) in terms of radius.

[elletruchan2I]

Hi RJ!
I do not think you will need to calculate ionic radius, but just know the trends it takes, that anions become bigger while cations becomes smaller, and why this is the case.

[butteredbread]

will the ionic radius usually be given for calculations?