Question

Shown at the right is a three-dimensional unit cell pattern for a structure of packed spheres. The center of each of eight spheres is at a corner of the cube, and the part of each that lies within the boundaries of the cube is shown. If all of the sphere segments enclosed inside the unit cell boundaries could be glued together, how many whole spheres could be constructed? Which ion of each pair is larger? Hint: How do the sizes of cations and anions compare to the size of the neutral atom they came from? What are the trends in size of atoms in the periodic table? Circle your choice. A. Na or CI B. Zn2 or S

Answer 1

1) there are eight corners in cube.

each sphere contribute 1/8 th of sphere.

number of sphere in unit cell = 8 * 1 / 8 = 1 (answer).

2)

In the periodic table, from left to right size of the element decreases due to increasing the effective nucler charge.

from top to bottom, size of the element decreases.

with increasing the positive charge on element, size decreses. so size of the neutral atom is greater than cation.

when one or more electron take in valence orbital then element covert to anion. size increases due to electron electron repulsion.

cosidering this,

A) Cl- ion have larger size.

B) S^2- have larger size.