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The element that does not show catenation is:
A. Sn
B. Ge
C. Si
D. Pb


Answer
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Hint: Catenation involves the formation of covalent bonds by the atom continuously to form a long chain or a ring of the compounds or the molecules by that element. As it involves the formation of covalent bonds, it is preferred by the non-metals and not by the metals.

Complete step by step solution:
-The periodic table contains three types of elements which are metals, metalloids and nonmetals. The trend in the periodic properties is repetitive and is called periodicity. There is a trend in the nature of the elements also.
-The elements of the groups 1, 2 and 3 are generally metals and those of group 15,16,17,18 are non-metals. Metalloids lie midway between the metals and the non-metals.
-The transition in the metallic character also occurs both along the period and down the group. Along the period, the number of electrons increases and so does the electronegativity. So the metallic character decreases along the period.
-Down the group, the size of the atom increases due to the increase in the number of the shells. This reduces the electronegativity of the atoms and so down the group, the metallic character increases.
-Catenation involves the formation of covalent bonds. It refers to the binding of the elements with themselves such that they form a chain or a ring with the help of covalent bonds. It changes the physical and chemical properties of the element drastically.
-As covalent bonding takes place in the process, it is a characteristic of a non-metal. Metals have the tendency to form the ionic bonds by losing their electrons while covalent bonds are formed by the non-metals by sharing of electrons.
-All the given elements belong to group 14 of the periodic table. We know that the metallic character increases down the group. So lead is the most metallic of them all and so it has the tendency to form ionic bonds and not the covalent bond. So it cannot show catenation.

Therefore the correct option is D.

Note: Covalent bonds are formed by the atoms to attain their noble gas configuration by sharing of the electrons. It is possible if the difference in the electronegativities of the atoms forming the bond is less. This is why non-metals form this bond. Carbon has the highest tendency to show catenation.