gem chem question

[CHCH]

For the atomic radii, mg2+ has a smaller radii than P, but why?

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[thedarkhorse]

For the atomic radii, mg2+ has a smaller radii than P, but why?

first off, as a general rule, the more negative the the element, the bigger its radius would be. since Mg 2+ is more positive than P it has a smaller radii. this means that the 12 electrons that would normally fill the Mg orbitals is now reduced to 10 electrons in its radius.

 

[Aug18DAT]

Rule 1. More negative the element, the bigger the radius.
Rule 2. Atomic radii increases as you go right to left and down the periodic table.

So, according to rule 1: Mg2+ is more positive than P, so Mg2+ is smaller than P
also Mg2+ = Ne and Ne is in Group 8 and P is in group 5, therefore P has greater atomic radii than Ne (Mg2+)

Below would be in order of increasing radii

Ca2+ < K+ < Cl- < S2- < p3-
more positive-----> more negative

 

[Hockey4life]

Also think about the effective nuclear charge as it explains alot of trends of periodic table. When mg2+ has 10e it has same number of protons which binds them more tightly hence smaller whereas in an anion number of electrons is increased and nuclear charge is less