Question

Lithium ions in Lithium selenide (Li2Se) have an atomic radius of 73 pm whereas the selenium ion is 184 pm. This compound is most likely to adopt a:Select the correct answer below:

a. closest-packed array with lithium ions occupying tetrahedral holes
b. closest-packed array with lithium ions occupying octahedral holes
c. body-centered cubic array with lithium ions occupying cubic holes
d. none of the above

Answer 1

closest-packed array with lithium ions occupying tetrahedral holes

Step-by-step explanation:

Given the small size of lithium ions and that they are present in twice the amount as selenide ions, they must occupy tetrahedral holes in a closest-packed array.

Answer 2

Step-by-step explanation:

Formula according to the radius ratio rule is as follows.

`(r_(+))/(r_(-)) = (73)/(184)`

= 0.397

According to the radius ratio rule, as the calculated value is 0.397 and it lies in between 0.225 to 0.414. Therefore, it means that the type of void is tetrahedral.

Thus, we can conclude that the given compound is most likely to adopt closest-packed array with lithium ions occupying tetrahedral holes.