Unit Cell

Unit Cell

How many formula units are in the unit cell shown for li2S?

The inorganic compound, Lithium sulfide depicts formula as Li2S. The compound is known for crystallizing with the antifluorite motif, which demonstrates the formula of salt, (Li+)2 S2-. A solid deliquescent power of the color solid yellow-white is generated from the compound. The inorganic compound can easily hydrolyze when is reacted with air, therefore release a rotten egg smell, which is known as hydrogen sulfide.

The inorganic compound is formed through the treatment of lithium with another element, sulfur. The reaction of conversion is facilitated with the presence of anhydrous ammonia. The chemical equation depicting the equation of Lithium Sulfide is given below:
2 Li + S → Li2S

The application of Lithium Sulfide can be witnessed in the batteries, named as Lithium-sulfur batteries.

The inorganic compound reflects a crystal structure, which is known as antifluorite crystal structure. The formed crystal structure reflects the presence of FCC lattice cations, which are filled in the holes of tetrahedral along with anions. The crystalized structure includes a total of 4 atoms with 12 as the coordination number.

The unit cell of Li2S reflects the presence of S-2 ions that are CCP. The unit cell has the capacity of adopting a cubic arrangement which is face-centered. The S-2 ions are yellowish in color. All the other tetrahedral holes that are eight in number are occupied by the Li+ ions. The Li+ ions are pink in color. Ion depicts the presence of tetrahedral hole with four as its coordination number. The inorganic compound Lithium Sulfide contains unequal rate of anions and cations , which makes the number of ionic compound unequal. Due to the presence of Li+ is twice as the presence of S2-, which makes coordination number of Li+, half as the element of S2-. Thus, coordination number is eight for S2- and the coordination number of Li+ is 4 in the unit cell of Lithium Sulfide. Unit cell of Lithium Sulfide contains = 4 S2- ions 8 Li+ ions.