The earth’s crust has only 0.02% carbon in the form of minerals (like carbonates, hydrogen carbonates, coal and petroleum) and the atmosphere has 0.03% of carbon dioxide
The shared pair of electrons is said to constitute a single bond between the two hydrogen atoms.
The two electrons contributed by each oxygen atom give rise to two shared pairs of electrons. This is said to constitute a double bond between the two atoms
In order to attain an octet, each nitrogen atom in a molecule of nitrogen contributes three electrons giving rise to three shared pairs of electrons. This is said to constitute a triple bond between the two atoms.
Bonds which are formed by the sharing of an electron pair between two atoms are known as covalent bonds.
Both diamond and graphite are formed by carbon atoms
In diamond, each carbon atom is bonded to four other carbon atoms forming a rigid three-dimensional structure
In graphite, each carbon atom is bonded to three other carbon atoms in the same plane giving a hexagonal array
4.2 VERSATILE NATURE OF CARBON
Carbon has the unique ability to form bonds with other atoms of carbon, giving rise to large molecules. This property is called catenation.
Compounds of carbon, which are linked by only single bonds between the carbon atoms are called saturated compounds. Compounds of carbon having double or triple bonds between their carbon atoms are called unsaturated compounds.
Since carbon has a Valency of four, it is capable of bonding with four other atoms of carbon or atoms of some other mono-valent element.
Compounds with identical molecular formula but different structures are called structural isomers
All these carbon compounds which contain just carbon and hydrogen are called hydrocarbons. Among these, the saturated hydrocarbons are called alkanes. The unsaturated hydrocarbons which contain one or more double bonds are called alkenes. Those containing one or more triple bonds are called alkynes
Compounds, the element replacing hydrogen is referred to as a heteroatom. These heteroatoms confer specific properties to the compound, regardless of the length and nature of the carbon chain and hence are called functional groups
A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series
The general formula for alkenes can be written as CnH2n , where n = 2, 3, 4.
Saturated hydrocarbons will generally give a clean flame while unsaturated carbon compounds will give a yellow flame with lots of black smoke.
The formation of oxides of sulphur and nitrogen which are major pollutants in the environment.
Substances are capable of adding oxygen to others. These substances are known as oxidising agents
Ethanol is commonly called alcohol and is the active ingredient of all alcoholic drinks.
In addition, because it is a good solvent, it is also used in medicines such as tincture iodine, cough syrups, and many tonic
Ethanol is also soluble in water in all proportions.
Sugarcane plants are one of the most efficient convertors of sunlight into chemical energy. Sugarcane juice can be used to prepare molasses which is fermented to give alcohol (ethanol).
Esters are sweet-smelling substances. These are used in making perfumes and as flavouring agents. Esters react in the presence of an acid or a base to give back the alcohol and carboxylic acid. This reaction is known as saponification because it is used in the preparation of soap.
Detergents are generally ammonium or sulphonate salts of long chain carboxylic acids
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