Solveeit Logo

Question

Question: The correct statement for the molecule \(Cs{{I}_{3}}\) is that: (A) It contains \(C{{s}^{3+}}\) a...

The correct statement for the molecule CsI3Cs{{I}_{3}} is that:
(A) It contains Cs3+C{{s}^{3+}} and I{{I}^{-}} ions
(B) It contains Cs+C{{s}^{+}},I{{I}^{-}} and lattice I2{{I}_{2}} molecule
(C) It is a covalent molecule
(D) It contains Cs+C{{s}^{+}} and I3{{I}_{3}}^{-} ions

Explanation

Solution

Caesium is a group one element and iodine is a group seven element or halogen. Usually group one elements don't show +3 oxidation state. Like this we can examine each of the given options according to the properties of Caesium and iodine and we would be able to find the correct statement.

Complete step by step answer:
- The CsI3Cs{{I}_{3}} molecule is called as Caesium triiodide .Lets check each of the given statements and verify them.
(i) It contains Cs3+C{{s}^{3+}}and I{{I}^{-}} ions
- Caesium is a group one element and group one element does not exhibit +3 oxidation states. Hence the possibility of forming Cs3+C{{s}^{3+}} is excluded and this option is incorrect.

(ii) It contains Cs+C{{s}^{+}},I{{I}^{-}} and lattice I2{{I}_{2}} molecule
- As we know iodine is a halogen molecule which is located at the right side of the periodic table and hence it is larger in size. Since I2{{I}_{2}} molecule is large it cannot be accommodated in the crystal lattice of CsI3Cs{{I}_{3}} molecule. Thus option (B) is wrong.

(iii) It is a covalent molecule
-Cations are formed when a metal loses its valence electrons and an anion is formed when a nonmetal gains an electron and an ionic bond is formed as a result of the electrostatic force between them. . In the case of covalent bonds the electrons are shared between the two atoms.
-As we mentioned Caesium is a group one element (electropositive) and iodine is a halogen (highly electronegative).They always tend to form ionic bonds. Hence CsI3Cs{{I}_{3}} is an ionic compound. Thus option (C) can be excluded.

(iv) It contains Cs+C{{s}^{+}}and I3{{I}_{3}}^{-} ions
- CsI3Cs{{I}_{3}} on dissociation gives Cs+C{{s}^{+}} and I3{{I}_{3}}^{-} and this I3{{I}_{3}}^{-} on dissociation gives I2{{I}_{2}} and I{{I}^{-}}.This dissociation can be represented as follows
CsI3Cs++I3Cs{{I}_{3}}\to C{{s}^{+}}+{{I}_{3}}^{-}
I3I+I2{{I}_{3}}^{-}\to {{I}^{-}}+{{I}_{2}}
Thus this statement is correct.
So, the correct answer is “Option D”.

Note: Keep in mind that the molecular weight of Caesium triiodide is 513 grams. Also do not confuse Caesium iodide with Caesium triiodide. Caesium iodide has a molecular formula of CsI and Caesium triiodide has the molecular formula CsI3Cs{{I}_{3}}. Iodide is a monatomic, uni-negative anion and triiodide is a triatomic, uni-negative anion.