Carbon

What is Catenation in Carbon

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What is Catenation in Carbon

Another peculiar behaviour of carbon is its ability to form longest chains with its own atoms. If any element forms bonds between its own atoms to give big molecules we call that property as catenation property.
Carbon has the ability to form longest chains containing millions of carbon atoms in molecules like some proteins. Sulphur, phosphorus and some other non metals have this property but to a very less extent.

You have understood that carbon can form:
a) Four single covalent bonds ,
What is Catenation in Carbon 1
b) A double bond and two single covalent bond s (C = C)
c) A single covalent bond and a triple bond (–C ≡ C), or two double bonds (C = C = C) with its own atoms or atoms of other elements to satisfy its tetravalency.

This ability of carbon to form bonds in so many ways made it as versatile element in nature. Hence, carbon’s ability
1) to form largest number of compounds
2) to show catenation
3) to form various types of bonds made it the versatile element.

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Explain the Versatile Nature of Carbon

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Explain the Versatile Nature of Carbon

By the eighteenth century scientists tried to explain the difference between the compounds in a broader way.
J. J. Berzelius (1807) named the compounds that derived from living organism as organic compounds and those from non-living materials as inorganic compounds. He thought that organic compounds would be prepared in the living bodies through vital force, the essence of life. As this force is absent outside the living bodies, it was thought that the so called organic compounds could not be synthesized in the laboratories.
Surprisingly F. Wohler (1828) produced an organic compound Urea in the laboratory by heating an inorganic salt ammonium cyanate.
Explain the Versatile Nature of Carbon 1It inspired many other chemists and they were successful to prepare the so called organic compounds, methane, acetic acid etc., in the laboratory. This gave a death blow to the idea that organic compounds are derived from living organism. Chemists thought about a new definition for organic compounds. After observing the structures and elements of organic compounds, they defined organic compounds as compounds of carbon. Therefore, organic chemistry is totally allotted to carbon compounds.

We understand that all molecules that make life possible carbohydrates, proteins, nucleic acids, lipids, hormones, and vitamins contain carbon. The chemical reactions that take place in living systems are of carbon compounds. Food that we get from nature, various medicines, cotton, silk and fuels like natural gas and petroleum almost all of them are carbon compounds. Synthetic fabrics, plastics, synthetic rubber are also compounds of carbon. Hence, carbon is a special element with the largest number of compounds.

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What is an sp3 Hybridized Carbon atom

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What is an sp3 Hybridized Carbon atom

sp3 Hybridisation

In the excited carbon atom its one s-orbital (2s) and three p-orbitals (2px , 2py, 2pz) intermix and reshuffle into four identical orbitals known as sp3 orbitals. Thus, carbon atom undergoes  sp3 hybridisation.
The four electrons enter into the new four identical hybrid orbitals known as sp3 hybrid orbitals one each as per Hund’s rule. (because they are made from one ‘s-orbital’ and three ‘p-orbitals’ they are called sp3 orbitals).
What is an sp3 Hybridized Carbon atom 1
The hybridisation enables the carbon to have four identical sp3 hybrid orbitals and these have one electron each. Since carbon has four unpaired electrons, it is capable of forming bonds with four other atoms may be carbon or atoms of some other monovalent element. When carbon reacts with hydrogen, four hydrogen atoms allow their ‘s’ orbitals containing one electron each to overlap the four sp3 orbitals of carbon atom which are orieted at an angle of 109°28′. (Four orbitals of an atom in the outer shell orient along the four corners of a tetrahedron to have minimum repulsion between their electrons). The nucleus of the atom is at the centre of the tetrahedron. See figures below:
What is an sp3 Hybridized Carbon atom 2
This leads to form four sp3 – s sigma bonds between carbon atom and four hydrogen atoms. All these bonds are of equal energy.

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Is Carbon a metal, nonmetal or metalloid

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Is Carbon a metal, nonmetal or metalloid

The food you eat, the clothes you wear, the cosmetics you use, the fuels you use to run automobiles are all the compounds of carbon.
Carbon was discovered in prehistory and it was known to the ancients.
They used to manufacture charcoal by burning organic material.
Carbon is a non-metal. It belongs to the fourteenth group or IV A group in the modern periodical table. The elements of this group have four electrons in the valence shell.
Let us write the electronic configuration of Carbon (6C).
Atomic number of carbon is 6.
Electronic configuration of carbon (ground state) 6C: 1s2 2s2 2p2. To get the octet in its outer shell it has to gain four more electrons to form C4-. The electronegativity of carbon is only 2.5 and its nucleus has only six protons. Therefore it would be difficult for a nucleus with six protons to hold ten electrons. Hence, carbon cannot form C4- ions so easily.
If carbon loses four electrons from the outer shell, it has to form C4+ ions. This requires huge amount of energy which is not available normally.
Therefore C4+ formation also is a remote possibility. Carbon has to satisfy its tetravaiency by sharing electrons with other atoms. It has to form four covalent bonds either with its own atoms or atoms of other elements.
The possibility of bonds formation by a carbon atom is as:
a) i. Four single covalent bonds, with atoms of same element like hydrogen, Chlorine.
Is Carbon a metal, nonmetal or metalloid 1
ii. Four single covalent bonds with atoms of different elements ;
Is Carbon a metal, nonmetal or metalloid 2
b) Carbon atoms may form one double bond and two single bonds
Is Carbon a metal, nonmetal or metalloid 3
c) Carbon atom may form one single bond and a triple bond
Eg: H–C ≡ C–H or CH3–C ≡ N or carbon atoms may also form two double bonds as in CH2 = C = CH2.

Carbon atomic number is 6. Its mass number is 1.20. Its atomic mass is 12.011. Its melting point is 3550ºC and boiling point is 4830ºC. It occurs in free state as well as in combined state. 70% of our body is made up of carbon. It forms largest number of compounds. The earth crust contains only 0.02% of carbon.

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