CARBON AND ITS COMPOUNDS

SCIENCE HOLIDAY HOMEWORK

WHAT IS CARBON?

• Food, clothes, medicines, books, or many other things are all based on carbon.

• The amount of carbon present in the Earth’s crust and atmosphere is quite meagre.

• 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.

• In spite of this small amount of carbon available in nature, the importance of carbon seems to be immense.

THE COVALENT BOND• The relativity of an element is explained as their

tendency to attain a completely filled outer shell, i.e., attain noble gas configuration.

• In the case of carbon, it has four electrons in its outermost shell and needs to gain or lose four electrons to attain noble gas configuration.

I] It could gain four electrons forming C4- anion. Nut it would be difficult for the nucleus with 6 protons to hold on to 10 electrons.

II] it could lose four electrons forming C4+. But it would require a large amount of energy to remove four electrons leaving behind a carbon cation with 6 protons holding just 2 electrons.

• Carbon overcomes this problem by sharing its valence electrons with other atoms of carbon or with atoms of other elements.

• The simplest molecule formed in this manner is that of Hydrogen is 1. hence hydrogen has one electron in its K shell and it requires one more electron to fill the K shell. So two hydrogen atoms share their electrons to form a molecule of Hydrogen, H2. this allows each Hydrogen atom to attain the electronic configuration of the nearest noble gas, Helium, which has two electrons in its K shell.

• In the case of Oxygen, we see the formation of a double bond between in its L shell.

HYDROGEN: SUNGLE BONDOXYGEN: DOUBLE BONDNITROGEN: TRIPLE BOND

ALLOTROPES OF CARBON

• The element carbon occurs in different forms in nature with widely varying physical properties. Both Diamond and Graphite are formed by carbon atoms, the difference lies in the manner in which the carbon atoms are bonded to four other carbon atoms in the same plane giving a hexagonal array.

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. These compounds may have long chains of carbon, branched chains of carbon or even carbon atoms arranged in rings.

• 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 of carbon are formed with oxygen, hydrogen, nitrogen, sulphur, chlorine and many other elements other than carbon present in the molecule.

SATURATED AND UNSATURATED COMPOUNDS• The compounds of carbon, which are

linked by only single bonds between the carbon atoms are called saturated compounds. They are less reactive than unsaturated carbon compounds.

• Compounds of carbon having double or triple bonds between carbon atoms are called unsaturated carbons. They are more reactive than saturated carbon compounds.

CHAINS, BRANCHES AND RINGS• The compounds with different structures but

with identical molecular formula are called structural isomers.

• A carbon compound can be formed in addition to chain, braches also in the form of a ring. Ex: Cyclohexane.

• Straight, branched chain and cyclic carbon compounds, all may be saturated or unsaturated. Ex: Benzene.

• All these carbon compounds which contain just carbon and hydrogen are called hydrocarbons.

• The saturated hydrocarbons are called alkenes.• The unsaturated hydrocarbons are called

alkynes.

C4H10 – Branched chain

CYCLOHEXANE – C6H12

BENZENE – C6H6

FUNCTIONAL GROUPS• In compounds element replacing hydrogen

is referred to as a heteroatom.• These heteroatom's and the group

containing these confer specific properties, regardless of the length and nature of the carbon chain and hence are called functional groups.

HOMOLOGOUS SERIES• Carbon atoms are linked together to form a chain.

• The presence of a functional group indicates the properties of that group.

• The general formula for alkenes can be written as CnH2n, where n = 2, 3, 4.

Methane - CH4

Ethane - C2H6

Propane - C3H8

Butane - C4H10

Pentane - C5H12

NOMENCLATURE• Naming a carbon compound can be done by the

following method-1) Identify the number of carbon atoms in the

compound. 2) In case a functional group is present, it is

indication in the name of the compound with either a prefix or a suffix.

3) If the name is given a suffix, the name of the carbon chain is modified by deleting the final ‘e’ and adding the appropriate suffix.

4) If the carbon chain is unsaturated the final letter ‘ane’ in the name of the carbon chain is substituted by ‘ene’ or ‘yne’.

CHEMICAL PROPERITES OF CARBON COMPOUNDS

SOME IMPORTANT CARBON COMPOUNDS• ETHANOL: 1) Ethanol is a colourless liquid with a

pleasant smell and burning taste. 2) it is soluble in water 3) Ethanol reacts with sodium to form

sodium ethoxide and hydrogen. 2C2H5OH + 2Na -------- 2C2H5ONa + H2 4) Ethanol reacts with hot concentrated

H2SO4 to form ethene and water.

• ETHANOIC ACID:1) Ethanoic acid is commonly called as

acetic acid.2) It belongs to carboxylic acid group.3) 5-8% of ethanoic acid in water is called

vinegar.4) It often freezes during winter that's why it

is also called glacial acetic acid.

SOAPS

SOAPS:• Most dirt is in oily in nature and oil does

not dissolve in water.• The molecules of soap are sodium or

potassium salts of long-carbon carboxylic acids.

• The ionic-end of a soap dissolves in water while the carbon chain dissolves in oil. The soap molecules, thus form structures called micelles, where one end of the molecules is towards the oil droplet while the ionic end faces outside.

DETERGENT

• The bating foam is formed in an insoluble substance after washing the water. This is caused by the reaction of soap with the calcium and magnesium salts.

• This problem is overcome by using detergents.

• Detergents are generally ammonium or sulphonate salts of long chain carboxylic acids. The charged ends of these compounds do not form insoluble precipitates with the calcium and magnesium.

THANK YOU...

MADE BY: C.ABHIRAMCLASS: X-B

ROLL NUMBER: 29