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Group 14 (Carbon Family): Physical Properties - 2 is considered one of the most asked concept.
48 Questions around this concept.
Given below are two statements:
Statement I: $\mathrm{SiO}_2$ and $\mathrm{GeO}_2$ are acidic while $\mathrm{SnO}$ and $\mathrm{PbO}$ are amphoteric in nature.
Statement II: Allotropic forms of carbon are due to property of catenation and $\mathrm{p} \pi-\mathrm{d} \pi$ bond formation. In the light of the above statements, choose the most appropriate answer from the options given below:
Out of the given options, which one are the Lewis acid
Which of the following is true about freons?
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Which of the following compounds is an example of Freon?
An excited hydrogen atom emits light in the ultraviolet region at 2.47 x 1015 Hz. With this frequency, the energy of a single photon is :
(h = 6.63 x 10-34 Js)
Select the correct option representing the number of compounds which are isostructural to
Consider the oxides of group 14 elements
$\mathrm{SiO}_2, \mathrm{GeO}_2, \mathrm{SnO}_2, \mathrm{PbO}_2, \mathrm{CO}$ and $\mathrm{GeO}$. The amphoteric oxides are
Electronic Configuration
The valence shell electronic configuration of these elements is ns2np2. The inner core of the electronic configuration of elements in this group also differs.
Covalent Radius
There is a considerable increase in covalent radius from C to Si, thereafter from Si to Pb a small increase in radius is observed. This is due to the presence of completely filled d and f orbitals in heavier members.
Ionization Enthalpy
The first ionization enthalpy of group 14 members is higher than the corresponding members of group 13. The influence of inner core electrons is visible here also. In general, the ionisation enthalpy decreases down the group. The small decrease in from Si to Ge to Sn and slight increase in
from Sn to Pb is the consequence of poor shielding effect of intervening d and f orbitals and increase in size of the atom.
Electronegativity
Due to small size, the elements of this group are slightly more electronegative than group 13 elements. The electronegativity values for elements from Si to Pb are almost the same.
Allotropy
The ability of an element to exist in more than one physical form is called allotropy. All the elements of this group except Pb exhibit allotropy. Carbon has three allotropes i.e, diamond, graphite and fullerene
Valency
All the elements of this group show tetravalency as they have 4 electrons in their valence shell.
Atomic and Ionic radii
As we move down the group, the radius of these elements increases.
Multiple Bonding
Carbon forms p-p
bonding with itself and with S, N and O. While the other elements of this group form p
-d
bonding as they have a vacant d-orbital while carbon does not have.
Hydrides
Halides
These elements can form halides of formula MX2 and MX4 (where X = F, Cl, Br, I). Except carbon, all other members react directly with halogen under a suitable condition to make halides. Most of the MX4 are covalent in nature. The central metal atom in these halides undergoes sp3 hybridisation and the molecule is tetrahedral in shape. Exceptions are SnF4 and PbF4, which are ionic in nature. PbI4 does not exist because Pb—I bond initially formed during the reaction does not release enough energy to unpair 6s2 electrons and excite one of them to higher orbital to have four unpaired electrons around lead atom. Heavier members Ge to Pb are able to make halides of formula MX2. Stability of dihalides increases down the group. Considering the thermal and chemical stability, GeX4 is more stable than GeX2, whereas PbX2 is more than PbX4. Except CCl4, other tetrachlorides are easily hydrolysed by water because the central atom can accommodate the lone pair of electrons from oxygen atom of water molecule in d orbital.
All members when heated in oxygen form oxides. There are mainly two types of oxides, i.e., monoxide and dioxide of formula MO and MO2 respectively. SiO only exists at high temperature. Oxides in higher oxidation states of elements are generally more acidic than those in lower oxidation states. The dioxides — CO2, SiO2 and GeO2 are acidic, whereas SnO2 and PbO2 are amphoteric in nature. Among monoxides, CO is neutral, GeO is distinctly acidic whereas SnO and PbO are amphoteric.
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