Carbon, a member of group 14, forms a large number of carbon compounds estimated to be about three million. Why is this property not exhibited by other elements of this group? Explain.

Carbon and its Compounds

Versatile Nature of Carbon

Official Answer

Carbon exhibits a unique ability to form a vast number of stable compounds due to two key properties—catenation and tetravalency—which are not shown to the same extent by other group 14 elements like silicon:

Catenation and Bond Strength: Carbon has the unique ability to form strong, stable covalent bonds with other carbon atoms, giving rise to long chains, branched chains, or rings. The carbon-carbon ( $C-C$ ) bond is exceptionally strong and stable. Other group 14 elements, such as silicon, can form chains with hydrogen up to only 7 or 8 atoms, but these compounds are highly reactive and unstable.
Small Atomic Size: Carbon has a very small atomic size compared to other elements in group 14. This small size enables its nucleus to hold on to the shared pairs of electrons strongly, resulting in exceptionally stable bonds. The bonds formed by other group 14 elements with larger atoms are much weaker.
Tetravalency: With a valency of four, carbon is capable of bonding with four other atoms of carbon or monovalent/divalent elements (like hydrogen, oxygen, nitrogen, sulphur, and halogens) using single, double, or triple bonds, creating a massive variety of stable structures.

catenationtetravalencysmall atomic sizestrong covalent bondssiliconreactiveweak bonds

Marking Scheme

11 Mark: Explaining catenation and stating that the carbon-carbon bond is exceptionally strong and stable, whereas other group 14 elements (like silicon) form weak, highly reactive chains.
21 Mark: Explaining the role of atomic size (carbon's small size allows the nucleus to hold shared electrons strongly, whereas larger group 14 atoms form much weaker bonds).
31 Mark: Mentioning tetravalency and the ability of carbon to form stable single, double, or triple bonds with carbon or other heteroatoms.

Hint

Think about how the atomic size of carbon compares to other group 14 elements like silicon, and how this size difference affects the strength and stability of their covalent bonds.

Quick Oral Answer

Carbon forms millions of compounds due to catenation and tetravalency. Its small atomic size allows it to form very strong and stable covalent bonds, whereas other group 14 elements like silicon have larger atomic sizes, making their bonds weak and highly reactive.

Analysis & Explanation

The versatile nature of carbon is primarily attributed to its small size and electronic configuration. Being in the second period of the periodic table, carbon has only two electron shells ( $K$ and $L$ ), making its atomic radius small. This small radius allows the positively charged nucleus to exert a strong electrostatic pull on the shared pair of electrons in a covalent bond, making the $C-C$ bond highly stable. Down the group (e.g., Silicon, Germanium), the atomic size increases significantly due to the addition of inner electron shells. Consequently, the nucleus cannot hold the shared pair of electrons as strongly, making their homonuclear bonds (like $Si-Si$ ) much weaker and highly reactive. Thus, silicon's catenation is limited to only 7-8 atoms, and it cannot form a vast array of stable compounds like carbon does.

Common Mistakes

1Stating that other group 14 elements do not show catenation at all (silicon does show catenation up to 7-8 atoms, but the compounds are highly reactive).
2Forgetting to mention the role of atomic size in determining bond strength.

Interesting Facts

It was once believed that organic carbon compounds could only be formed within living systems under a 'vital force'. Friedrich Wöhler disproved this in 1828 by preparing organic urea from inorganic ammonium cyanate.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2020?

This question carries 3 marks in the CBSE Class 10 Science 2020 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Carbon and its Compounds" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Versatile Nature of Carbon" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2020 paper?

This is a Short Answer question from Section B in the CBSE Class 10 Science 2020 paper.