What is the molecular structure for each of the following molecules or ions? a. OCl2 b. ClO4- c. ICl5
What is the molecular structure for each of the following molecules or ions? a. OCl2
b. ClO4-
c. ICl5
d. PF6
The Correct Answer and Explanation is :
The molecular structures of the given molecules and ions are as follows:
a. OCl₂ (Dichlorine monoxide):
- Molecular Structure: OCl₂ has a bent or V-shape structure.
- Bond Angles: The bond angle between the chlorine atoms is approximately 111°.
- Explanation: OCl₂ consists of one oxygen atom bonded to two chlorine atoms. Oxygen, being more electronegative than chlorine, has two lone pairs of electrons. This lone pair of electrons pushes the bonding pairs closer together, leading to a bent shape. The oxygen atom has two single bonds with the chlorine atoms, and the molecule follows the VSEPR (Valence Shell Electron Pair Repulsion) theory. The oxygen atom has an electron pair repulsion that causes the bond angle to deviate slightly from the ideal 120° angle of a trigonal planar structure.
b. ClO₄⁻ (Perchlorate ion):
- Molecular Structure: The structure of the perchlorate ion is tetrahedral.
- Bond Angles: The bond angles are 109.5°.
- Explanation: In the ClO₄⁻ ion, the central chlorine atom is bonded to four oxygen atoms in a tetrahedral arrangement. The chlorine atom has an expanded valence shell, allowing it to accommodate more than eight electrons. The ion carries a negative charge, which is delocalized over the oxygen atoms, contributing to the stability of the structure. The tetrahedral shape results from the electron repulsion of the four bonding pairs, leading to an ideal bond angle of 109.5°.
c. ICl₅ (Iodine pentachloride):
- Molecular Structure: The structure of ICl₅ is square pyramidal.
- Bond Angles: The bond angles between the chlorine atoms are approximately 90° for the equatorial positions and 81.8° for the axial positions.
- Explanation: ICl₅ consists of an iodine atom in the center bonded to five chlorine atoms. The iodine atom follows the octet rule and can expand its valence shell to accommodate more electrons due to its position in the fifth period of the periodic table. In the square pyramidal arrangement, there are four chlorine atoms in a plane around the iodine atom, and one chlorine atom positioned above or below this plane. The lone pair of electrons on the iodine atom pushes the chlorine atoms into this particular configuration.
d. PF₆⁻ (Hexafluorophosphate ion):
- Molecular Structure: The structure of PF₆⁻ is octahedral.
- Bond Angles: The bond angles are 90° between adjacent fluorine atoms.
- Explanation: In PF₆⁻, the phosphorus atom is surrounded by six fluorine atoms in an octahedral geometry. The phosphorus atom uses all six of its valence electrons to form bonds with the fluorine atoms. The electron pair repulsion between the fluorine atoms forces the geometry into an octahedral shape, with bond angles of 90° between each adjacent fluorine. The ion carries a negative charge, which is delocalized, but the overall structure remains stable in this octahedral arrangement.
These structures are determined by VSEPR theory, which minimizes electron repulsion to predict the shapes of molecules and ions.