Courses
Courses for Kids
Free study material
Offline Centres
More
Store Icon
Store
seo-qna
SearchIcon
banner

The shape of [Fe(CN)6]4ion is
A.Hexagonal
B.Pyramidal
C.Octahedral
D.Octagonal

Answer
VerifiedVerified
404.7k+ views
like imagedislike image
Hint: To find the shape we need to find the hybridization. To find hybridization, first draw the Lewis structure to get a rough idea about the structure of the molecule and bonding pattern. Use the valence concept to arrive at this structure. Concentrate on the electron pairs and other atoms linked directly to the concerned atom. Using the Lewis structure, calculate the number of sigma (σ) bonds and the number of lone pairs. Then calculate the steric number. Steric number is the sum of the number of σ-bonds and the number of lone pairs. Now, based on the steric number, it is possible to get the type of hybridization of the atom. Consult the following table.
Steric numberhybridizationStructure
2spLinear
3sp2Trigonal planar
4sp3tetrahedral
5sp3dTrigonal bipyramidal
6sp3d2octahedral
7sp3d3Pentagonal bipyramidal


Complete answer:
Number of σ-bonds formed by the atom in a compound is equal to the number of other atoms with which it is directly linked to.
The number of lone pairs on a given atom can be calculated by using the following formula.
Number of lone pairs=vbc2
Where v is number of valence electrons in the concerned atom in free state (i.e., before bond formation), bis number of bonds (including both σand πbonds) formed by concerned atom and cis charge on the atom.
The Lewis structure of [Fe(CN)6]4
seo images

From the above structure, the central atom of iron (Fe+2) is having 6 sigma bonds and no lone pair. Which implies that the steric number of [Fe(CN)6]4is equals to 6 and then the hybridization is sp3d.
Hence the geometry\shape of [Fe(CN)6]4 is octahedral.
Thus, the correct option is (C) Octahedral.

Note:
Planarity or nonplanarity is determined by shape/geometry which is further controlled by hybridisation of the central atom in the compound so by knowing the hybridisation we can tell whether a compound is planar or not. Hence, the molecule will not be planar if there is an sp3 hybridized carbon (or nitrogen) atom or two sp2 hybridized atoms of carbon (or nitrogen) which are separated by an even number of double bonds and no single bonds. Otherwise, its structure allows it to be planar. The polarity of a molecule is basically the measure of its dipole moment. If the dipole is a considerable number (not equal to zero), the molecule is said to be polar.