Question

highest lattice energy
csbr
licl
lowest lattice energy
answer bank
mgs
na₂o

Explanation:

Step1: Recall lattice - energy trend

Lattice energy is directly proportional to the product of ionic charges and inversely proportional to the ionic - radius sum.

Step2: Analyze ionic charges

In $MgS$, $Mg^{2 + }$ and $S^{2 - }$ have charges of + 2 and - 2 respectively. In $Na_2O$, $Na^+$ has a charge of + 1 and $O^{2 - }$ has a charge of - 2. In $CsBr$, $Cs^+$ has a charge of + 1 and $Br^-$ has a charge of - 1. In $LiCl$, $Li^+$ has a charge of + 1 and $Cl^-$ has a charge of - 1.

Step3: Analyze ionic radii

Ionic radii increase down a group. $Cs^+$ has a larger radius than $Li^+$, and $Br^-$ has a larger radius than $Cl^-$. Also, $Mg^{2+}$ has a relatively small radius and $S^{2 - }$ is not as large as some other anions.

Step4: Determine highest lattice - energy

$MgS$ has the highest product of ionic charges ($2\times2 = 4$) among the given compounds. So, it has the highest lattice energy.

Step5: Determine lowest lattice - energy

$CsBr$ has the lowest product of ionic charges among the non - single - charge compounds and relatively large ionic radii. So, it has the lowest lattice energy.

Answer:

Highest lattice energy: $MgS$
Lowest lattice energy: $CsBr$