In an ionic compound, the size of the ions affects the internuclear distance (the distance between the centers of adjacent ions)
, which affects lattice energy (a measure of the attractive force holding those ions together). Based on ion sizes, arrange these compounds by their expected lattice energy.
Note that many sources define lattice energies as negative values. Please arrange by the magnitude and ignore the sign.
a) Li₂S
b) Cs₂S
c) K₂S
d) Na₂S
e) Rb₂S
Lattice Energy is a type of potential energy which may be defined in as, energy that is required to break apart an ionic solid and convert its component atoms into gaseous ions. More technically, it is a measure of the energy contained in the crystal lattice of a compound, equal to the energy that would be released if the component ions were brought together from infinity.
Lattice energy of ionic compounds decreases with increasing ionic sizes. Since the anion is the same, we consider increase in cation sizes. We discover that for gtoi 1 cations; Li+<Na+<K+<Rb+<Cs+. The ionic lattice energy decreases in the reverse order. Li2S will show the largest lattice energy since it contains the smallest cation in the list.
Molecular compounds consist of two or more nonmetals. The nonmetals that make up a molecular compound are held together by covalent/molecular bonds. Covalent bonds is known as the "sharing" of valence electrons between two or more chemical species. Valence electrons are shared so that the atoms of the compound can become stable, much like how ionic bonds transfer valence electrons between atoms to achieve stability.
