Try the fastest way to create flashcards
Question

# (a) Determine the radius of the smallest cation that can have (i) sixfold and (ii) eightfold coordination with the $\mathrm{Cl}^{-}$ ion (radius 181 pm). (b) Determine the radius of the smallest anion that can have (i) sixfold and (ii) eightfold coordination with the $\mathrm{Rb}^{+}$ ion (radius 149 pm).

Solution

Verified
Step 1
1 of 7

$\textbf{E15C3}$

(a) The deviation of a structure from that expected on the basis of this rule is often taken to be an indication of a shift from ionic towards covalent bonding. A major source of unreliability, though, is the arbitrariness of ionic radii and their variation with coordination number.

The radius-ratio rule is derived by considering the geometrical problem of packing the maximum number of hard spheres of one radius around a hard sphere of a different radius.

Thus,

Radius-ratio, $\gamma = \dfrac{r_{\text{smaller}}}{r_{\text{larger}}}$

= $\dfrac{r}{R}$

where, $r_{\text{smaller}}$ is the radius of the smaller ions in the crystal and $r_{\text{larger}}$ that of the larger ions.

## Recommended textbook solutions

#### Chemistry: The Molecular Nature of Matter and Change

7th EditionISBN: 9780073511177 (2 more)Patricia Amateis, Silberberg
6,032 solutions

#### Chemistry: The Central Science

14th EditionISBN: 9780134414232 (9 more)Bruce Edward Bursten, Catherine J. Murphy, H. Eugene Lemay, Matthew E. Stoltzfus, Patrick Woodward, Theodore E. Brown
7,736 solutions

#### Atkins' Physical Chemistry

11th EditionISBN: 9780198769866James Keeler, Julio de Paula, Peter Atkins
1,692 solutions

#### Modern Chemistry

1st EditionISBN: 9780547586632 (2 more)Jerry L. Sarquis, Mickey Sarquis
2,184 solutions