Using lewis struture:
Why is ICL2 a linear molecule and NH2 is a bent molecule.
Of the components Hg(OCN)2 and Hg(CNO)2 why is one explosive and the other isn’t?
The correct answer and explanation is :
Lewis Structures of ICl₂⁻ and NH₂
- ICl₂⁻ (Iodine dichloride anion):
The Lewis structure of ICl₂⁻ involves iodine (I) at the center, bonded to two chlorine (Cl) atoms. Iodine is in Group 17 and has 7 valence electrons, while each chlorine atom also has 7 valence electrons. The negative charge (⁻) is placed on the iodine atom. In the Lewis structure, iodine forms two single bonds with chlorine atoms and holds a lone pair of electrons. The molecular geometry of ICl₂⁻ is linear due to the steric repulsion between the bonding pairs and the lone pair of electrons on iodine, and this linear geometry minimizes the repulsion between all electron pairs. The electron pairs around iodine are arranged in a way that the bonding pairs are positioned 180° apart from each other, giving a linear shape. - NH₂ (Ammonia molecule):
The Lewis structure of NH₂ involves nitrogen (N) at the center, bonded to two hydrogen (H) atoms. Nitrogen has 5 valence electrons, and each hydrogen atom contributes 1 electron. Nitrogen also holds a lone pair of electrons. Since nitrogen has three regions of electron density (two bonding pairs and one lone pair), the electron geometry is trigonal planar. However, the lone pair of electrons causes repulsion that pushes the two hydrogen atoms closer together, resulting in a bent or angular molecular shape, with a bond angle of approximately 104.5°. This deviation from the ideal trigonal planar geometry is due to the lone pair-bond pair repulsion being stronger than bond-bond repulsion.
Why One is Explosive and the Other Isn’t:
- Hg(OCN)₂ (Mercury(II) cyanate) and Hg(CNO)₂ (Mercury(II) isocyanate) are both mercury compounds that involve cyanate (OCN⁻) and isocyanate (CNO⁻) ions, but their properties differ significantly.
- Hg(OCN)₂ (Mercury(II) cyanate) is non-explosive because the cyanate ion (OCN⁻) is a stable ion. The bonding within the cyanate ion involves a triple bond between carbon and nitrogen, with oxygen attached to the carbon atom. The overall structure of the cyanate ion is linear and highly stable due to the strong bonding and the delocalization of electrons. When mercury combines with cyanate ions, the compound is generally stable under normal conditions and doesn’t tend to undergo rapid decomposition or detonation.
- Hg(CNO)₂ (Mercury(II) isocyanate), on the other hand, is explosive due to the nature of the isocyanate ion (CNO⁻). In this ion, the nitrogen is bonded to the carbon atom, which is in turn bonded to the oxygen atom. The isocyanate ion is more prone to decomposition because of its less stable structure compared to the cyanate ion. The bonding in the isocyanate ion is less stable and can break down easily under certain conditions, especially in the presence of heat or shock, releasing gases such as nitrogen and carbon monoxide. This decomposition leads to a rapid release of energy, making Hg(CNO)₂ explosive.
In summary, the difference in the stability of the cyanate and isocyanate ions accounts for the differing reactivity of their respective mercury compounds, with Hg(CNO)₂ being explosive due to the instability of the isocyanate ion.