[alicia_tan2113]

The diagram shows the arrangement of the ions in an ionic crystal.



Blue= +ve ion
Green= -ve ion

Which compound cannot have this arrangement of its ions?

A Calcium Oxide, CaO
B Copper(II) Sulfate, CuSO₄
C Magnesium Chloride, MgCl₂
D Sodium Chloride, NaCl

The answer booklet says its C. My answer was B. I need to know why:) Thanks:)

[opti384]

Well if you see the picture you can see that there are 1 +ve ion and 1 -ve ion in a unit cell.

[Evaldas]

SO₄^2- is a complex ion, so one "bead" (I don't know how to call it exactly) represents one SO₄^2-, so in CuSO₄ ion ratio is 1:1, which is exactly what is shown in the picture, and in MgCl₂ ratio is 1:2, which doesn't match the picture.

[alicia_tan2113]

Thanks Evaldas:)

Now i get it:)