## Chemistry: The Central Science (13th Edition)

The cation-anion distance is estimated to be as follows: $Li-F: 2.09$ angstrom $Na-Cl: 2.83$ angstrom $K-Br: 3.34$ angstrom $Rb-I:3.72$ angstrom
The ionic radii of $Li^+$ is $0.90$ angstrom. The ionic radii of $F^-$ is $1.19$ angstrom. The ionic radii of $Na^+$ is $1.16$ angstrom. The ionic radii of $Cl^-$ is $1.67$ angstrom. The ionic radii of $K^+$ is $1.52$ angstrom. The ionic radii of $Br^-$ is $1.82$ angstrom. The ionic radii of $Rb^+$ is $1.66$ angstrom. The ionic radii of $I^-$ is $2.06$ angstrom. Now, to estimate the cation-anion distance, we would take the sum of the ionic radii of 2 ions in the ionic compound. In detail, - $Li-F:0.90+1.19=2.09$ angstrom - $Na-Cl:1.16+1.67=2.83$ angstrom - $K-Br:1.52+1.82=3.34$ angstrom - $Rb-I:1.66+2.06=3.72$ angstrom