Which of the following ions contains lone pair of electrons at the central atom?

A) SO4 2-
B) NO3 -
C) IO3 -

(Is there any ways without drawing the diagrams and I could still able to figure out the answer???)

Thx very much

No. As far as I know the Lewis Structure must be drawn.

I would look at IO3^- as the culprit.

Yes, there is a way to determine the answer without drawing the Lewis structures for each ion. You can use the concept of valence electrons.

For ions, you can find the number of valence electrons by considering the atomic number of the central atom and adding or subtracting electrons depending on the ion's charge.

In this case, let's compare the number of valence electrons for each ion:

A) SO4 2-:
Sulfur (S) is in Group 16 of the periodic table, so it has 6 valence electrons. Oxygen (O) is also in Group 16 and has 6 valence electrons. There are four oxygen atoms surrounding the sulfur, so in total, there are (6 + 6 × 4) + 2 extra electrons for the -2 charge = 32 + 2 = 34 valence electrons.

B) NO3 -:
Nitrogen (N) is in Group 15, so it has 5 valence electrons. Oxygen (O) is in Group 16 and has 6 valence electrons. We multiply the number of oxygen atoms by 3 because there are three oxygens in NO3-. With a -1 charge, there is one extra electron. So in total, there are (5 + 6 × 3) + 1 extra electrons for the -1 charge = 23 + 1 = 24 valence electrons.

C) IO3 -:
Iodine (I) is in Group 17, so it has 7 valence electrons. Oxygen (O) is in Group 16 and has 6 valence electrons. We multiply the number of oxygen atoms by 3 because there are three oxygens in IO3-. With a -1 charge, there is one extra electron. So in total, there are (7 + 6 × 3) + 1 extra electrons for the -1 charge = 26 + 1 = 27 valence electrons.

Now, to determine which ion has a lone pair of electrons at the central atom, we need to look for the ion with an odd number of valence electrons.

As you can see, all of the ions listed (SO4 2-, NO3 -, IO3 -) have an even number of valence electrons. In other words, none of them have a lone pair of electrons at the central atom.

Therefore, the answer is none of the above ions contains a lone pair of electrons at the central atom.