Find the number of molecules that are planar:
(i) SF₄
(ii) XeF₆
(iii) XeF₂
(iv) XeF₄
(v) H₂O
(vi) NH₃
(vii) PH₃
(viii) PCl₅
(ix) PCl₃
Answer (2)
The planar molecules from the list are XeF₂, XeF₄, and PCl₃, totaling 3 planar molecules. SF₄, XeF₆, H₂O, NH₃, PH₃, and PCl₅ are not planar. The shapes and arrangements of atoms in each of these molecules determine their planarity.
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To determine which molecules from the given list are planar, we need to consider the molecular geometry of each one. Planarity in a molecule means that the molecule's atoms lie in the same plane.
SF₄ (Sulfur Tetrafluoride):
SF₄ has a seesaw shape due to one lone pair on the sulfur atom. It is not planar.
XeF₆ (Xenon Hexafluoride):
XeF₆ is typically not a planar structure. It usually adopts a distorted octahedral geometry, making it non-planar.
XeF₂ (Xenon Difluoride):
XeF₂ has a linear geometry, which is planar. All the atoms lie on a straight line.
XeF₄ (Xenon Tetrafluoride):
XeF₄ has a square planar geometry, which means it is planar.
H₂O (Water):
The geometry of water is bent due to two lone pairs on the oxygen atom, which makes it not planar.
NH₃ (Ammonia):
Ammonia has a trigonal pyramidal shape due to the lone pair on nitrogen, which makes it non-planar.
PH₃ (Phosphine):
Similar to ammonia, PH₃ has a trigonal pyramidal geometry and is not planar.
PCl₅ (Phosphorus Pentachloride):
In its most stable form, PCl₅ has a trigonal bipyramidal shape, which is not planar. However, in the solid state, PCl₅ can have a trigonal planar structure in one of its forms but typically in gas phase it is non-planar.
PCl₃ (Phosphorus Trichloride):
PCl₃ has a trigonal pyramidal shape because of the lone pair on the phosphorus atom, making it non-planar.
Based on this analysis, the molecules that are planar are:
XeF₂
XeF₄
Therefore, the number of planar molecules in the provided list is 2.
