Carbon
Class 10 science chapter 4:- The name is derived from the Latin word ‘carbo’, which means ‘coal’. Carbon is non-metal. It is written with the symbol ‘C’. After oxygen and hydrogen, carbon is considered to be the third most important element. Our food, clothes, medicines, books are all made of carbon and the body of living beings (plants-animals) is made of carbon compounds. In the crust (under the ground), there is 0.02% carbon in the form of minerals (such as carbonates, hydrogen carbonates, coal, and petroleum). And in the atmosphere, 0.03% is in the form of carbon dioxide. In this artical learn the Class 10 science chapter 4 – carbon and its compounds class.
Covalent Bond
The bond which is formed by sharing electrons of the same type or different types of atoms is called a covalent bond.
There are three types of covalent bonds.
1) Single bond: Sharing of 1-1 electrons
2) Double bond: Sharing of 2-2 electrons
3) Triple bond: Sharing of 3-3 electrons
Covalent Bond in Carbon
Atomic number of carbon(C) – 6
Electronic configuration = K L
2 4
How does carbon form bonds?
Carbon is tetravalent. That is, it has 4 electrons in its outermost shell.
Carbon can complete its octet in two ways;
1) It can neither take 4 electrons because it is difficult to take 4 more electrons in a nucleus with 6 protons.
2) It can neither give 4 electrons because it would take a lot of energy to make a carbon cation of only 2 electrons in a nucleus with 6 protons by losing 4 electrons.
Therefore, carbon forms bonds by sharing electrons with its own atom or atoms of other elements.
In addition to carbon, hydrogen, oxygen, nitrogen, and chlorine also form bonds by sharing electrons.
Some examples depicting covalent bonding
1) Formation of hydrogen (H2) molecule
Number of atoms=1
Electronic configuration=K=1
1 electron is needed to fill the K shell.
Therefore, 2 atoms of hydrogen share their electrons to form a hydrogen molecule, H2.
In this way, both the hydrogen molecules acquire noble gas configuration.
The valence electrons are shown by crosses.
This bond is shown by a line between two atoms. A single bond shows an H2 molecule.
2) Formation of chlorine (Cl2) molecule
The atomic number of Cl=17
Electronic configuration=K L M
2, 8, 7
It has 7 electrons in its outermost shell, Cl needs 1 electron to complete its outer shell. This 1 electron can be taken away by sharing it with another Cl.
3) Formation of oxygen (O2) molecule
O’s atomic number=8
electronic configuration =2,6
It has 6 electrons2 in its outermost shell, it needs 2 electrons to complete its outer shell. It can share 2 electrons with another oxygen atom.
Each one of oxygen. The two electrons given off by the atoms give two participating pairs of electrons. This is called forming a double bond
between two atoms.
4) Formation of nitrogen (N2) molecule
Atomic number of N = 7
Electronic configuration =K L
2, 5
It has 5 electrons in its outer shell. It needs 3 more electrons to complete its outer shell. Therefore, two atoms of nitrogen share 3-3 electrons and form a triple bond to form a nitrogen molecule.
5) Molecule formation of ammonia (NH3)
Atomic number of N = 7
electronic configuration = KL
2,5 Atomic number of H = 1
electronic configuration = K = 1
Ammonia needs 3 electrons to complete the outer octet and hydrogen needs 1 electron.
To form one molecule of ammonia, 1 atom of nitrogen shares 1 electron from 3 hydrogens by its 3 electrons.
6) Formation of water (H2O) molecule
Atomic number of O = 8
Electronic configuration =KL
2,6
Atomic number of H = 1
Electronic configuration =K=1
Oxygen needs 2 electrons to complete its outer shell and hydrogen needs 1 electron. Therefore, by sharing among themselves, they become molecules.
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7) Formation of methane (CH4) molecule
Atomic number of C= 6
electronic configuration= 2,4
Atomic number of H= 1
electronic configuration= K=1
Carbon needs 4 electrons to complete its outer shell, and hydrogen needs 1 electron. Therefore, to complete the outer shell, a molecule of methane is formed by sharing carbon with 4 atoms of hydrogen.
Physical Properties of Covalent Compounds
1) These liquids have low melting and boiling points.
Because the intermolecular force between them is very less.
2) Covalent compounds are poor conductors of electricity because they do not form charged particles. It is formed by sharing of electrons.
Versatile Nature of Carbon
1) Catenation:
Carbon has the ability to form bonds with other atoms of carbon itself. Carbon can form long, open, or closed chains of bonds with its atoms. This property is called catenation.
2) Tendency to form multiple bonds
Due to the small size of the carbon atom, it can form a mistake bond. Carbon atoms are attached to each other or to other elements such as oxygen by single, double, or triple bonds. .
3) Tetravalency:
The valency of carbon is 4 so it is tetravalence. It has 4 electrons in its outer shell. To complete its shell, it can co-combine with carbon, oxygen, hydrogen, nitrogen, sulfur, and chlorine. Forms covalent bonds.
Nomenclature of Hydrocarbons:
Hydrocarbon molecules are named according to the presence of carbon atoms as follows:
Number of carbon atoms
1 Carbon atom Meth- (Meth)
2 Carbon atom Eth- (Eth)
3 Carbon atom Prop- (Prop)
4 Carbon atom But- (Buty ) )
5 Carbon Atoms Pent- ( Pent )
6 Carbon Atoms Hex- ( Hex )
7 Carbon Atoms Hept- ( Hept )
8 Carbon Atoms Oct- ( Oct )
9 Carbon Atoms Non – ( Non )
10 Carbon Atoms Dec – ( Deck )
Hydrocarbons;
Hydrocarbon; saturated and unsaturated carbon compounds
Saturated compounds
Compounds of carbon joined by only one bond between carbon atoms are called “saturated compounds”.
Example: All Alkanes Alkanes: Saturated hydrocarbons in which carbon atoms are attached only by single bonds are called alkane.
Such as methane, ethane, propane, and butane, etc.
The general formula for alkene : CnH2n + 2
To find the formula for methane using this formula : Substituting n = 1 in CnH2n + 2 we get :
C1H2x1 + 2 =CH4
Similarly ; For ethane: n = 2, we get:
C2H2x2= C2H4
Similarly, we can also make the formula and structure of propane, butane and pentane, etc. can.
Unsaturated compounds
Compounds of carbon having double or triple bonds are called “unsaturated compounds”. such as alkene and alkyne.
Alkenes: Unsaturated hydrocarbons in which carbon atoms are linked by double bonds are called alkene.
Eg: methine, ethene, propene, and butene.
General formula of alkene C2H2n
To get the formula for ethene,
n=2
C2H2x2= C2H4, similarly the formula and structure of propene and butene etc. can be made. Alkynes in which carbon atoms are linked by triple bonds. Like ethene, propene, butene, the general formula of alkynes C2H2n-2 To get the formula of ethene, n=2 C2H2x2-2= C2H4-2= C2H2 Similarly, formula and structure of propene, butene, etc. can be made.
Types of carbon chains
1) straight chain
2) Branched series
3) Ringed series
a) Cyclohexane (C6H12) [saturated]
b) Benzene (C6H6) [unsaturated]
Structural isomer
Compounds that have the same molecular formula but different structures are called isomers.
Example; Isomer of butane
straight chain. branched-chain
Functional Group
Elements that displace hydrogen in compounds are called heterogeneous atoms. These give specific properties to organic compounds. Hence they are called functional groups.
Nomenclature of carbon compounds
Compounds are named by adding a suffix (suffix) or a prefix (prefix) to the alkene according to the presence of the functional group.
Homologous Series
A series of compounds in which the same functional group replaces the hydrogen in the carbon chain is called a homologous series.
Features of Homogeneous Category
In this, the carbon compounds are arranged in increasing order of the number of carbon atoms present in it, there is a difference of CH2 between two consecutive compounds. there is a difference of 14u in the molecular mass of two consecutive compounds.
Chemical properties of Carbon Compound
1.Combustion
Organic compounds when burnt in oxygen form carbon dioxide and water vapor. Heat and light are released in this process. This reaction is called combustion.
C + O2→ CO2+ heat and light
CH4 +O2–> CO2+ H2O + heat and light
CH3CH2OH +O2→CO2+ H2O + heat and light
Combustion of saturated hydrocarbons gives a clean flame because they are completely burnt. Whereas unsaturated carbon compounds will give a yellow flame with very black smoke because they will not be completely combusted.
Fuel
Those carbon compounds, which have energy and burn with heat and light are called fuels, they use the released energy, heat, or light for various purposes such as cooking food, running machines in factories, etc.
Such as Coal, Coke, Charcoal, Petrol, Petroleum, etc.
Fossil fuel
The fuels which are buried in the rocks in the soil of old plants and animals for a long time are formed by decomposition.
such as coal and petroleum
2.oxidation
The process of taking oxygen or giving hydrogen is called oxidation.
Example,
alkaline kMnO4+heat
CH3CH2OH———————->CH3COOH
or acidified K2Cr2O7+heat
Some substances have the ability to give oxygen to other substances, these substances are called oxidizers.
For example, alkaline potassium permanganate or acidified potassium dichromate.
3. Addition Reaction
In the presence of a catalyst, unsaturated hydrocarbons combine with hydrogen to give saturated hydrocarbons.
Catalysts are substances that increase the rate of a reaction and do not affect the reaction. such as palladium or nickel.
Vegetable oil can be converted into vegetable ghee by hydrogenation using a nickel catalyst. This process is called hydrogenation.
Note:
Vegetable oils (unsaturated fats) are ‘healthy*.
Animal fats contain saturated fatty acids which are injurious to health.
Therefore, we should use oils containing unsaturated fats for cooking.
4. Substitution Reaction
The reaction in which one or more atom or group of atoms is replaced in an organic molecule is called a substitution reaction.
chlorination; The process of replacement of hydrogen atoms by chlorine atoms is called chlorination.
For example, when methine reacts in sunlight, chlorine displaces hydrogen atoms one by one.
In the presence of sunlight
CH4+Cl2—————->CH3Cl+HCl
Some Important Carbon Compounds: Ethanol and Ethanoic Acid
Properties of Ethanol
• Occurs in a liquid state at room temperature.
• Common name – Alcohol • Molecular formula –
C2H6OH
Structure formula – CH3CH2―OH
Soluble in water
Colorless odor and burning taste
Neutral in nature
Construction
Alcohol is prepared by fermentation of molasses (molasses) from sugarcane juice.
Chemical properties
- Reaction with sodium:
2Na+2CH3CH2OH――>2CH3CH2ONa+H2
• Alcohols react with sodium to form hydrogen gas. The new product sodium ethoxide is formed.
• Ethanol can be tested for the generation of hydrogen gas by this reaction.
2. Dehydration
When ethanol is heated with an excess of sulfuric acid at 443 K, ethanol dehydrates to form ethene.
Hot Concentrate
CH3―CH2OH——–>CH2=CH2+H2O
H2SO4
note:- In some countries, a mixture of alcohol and petrol is used as a clean fuel.
properties of ethanoic acid
A colorless liquid, sour in taste, odor like vinegar
Common name- acetic acid
3-4% solution is called vinegar.
Pure ethanoic acid has a melting point of 290 K.
It accumulates in cold climates, hence it is called glacial acetic acid.
Chemical properties
1.esterification
Esters are formed by reacting with ethanoic acid and alcohol in the presence of an acid catalyst.
CH3–COOH+CH3–CH2OH――>CH3–CO–
CH2–CH3+H2O
Esters are used to making perfumes or as a flavoring agent.
Soaping
Esters react in the presence of acid or base to form alcohol and carboxylic acid again. This reaction is called saponification because it produces soap.
CH3COOC2H5———–>C2H5OH+CH3COOH
2.Reaction with Base
Ethanoic acid reacts with a base such as sodium hydroxide to form salt and water.
NaOH+CH3COO—> CH3COONa+H2O
3.Reaction with Carbonate and Hydrogencarbonate:
Ethanoic acid reacts with carbonates and hydrogen carbonates to form salts, carbon dioxide, and water. The salt formed in this reaction is sodium acetate.
2CH3COOH+Na2CO3—–>
2CH3COONa+H2O+CO2
CH3COOH+NaHCO3–>
CH3COONa+H2O+CO2
soap and detergent
Soaps are sodium potassium salts of long-chain carboxylic acids.
Example- C17H35COONa
soap only cleans with soft water.
Structure of soap molecule
1. Hydrophobic head (ionic part)
2. Hydrophobic end (long hydrocarbon chain)
Soap cleaning process
The mixtures are oily. The hydrophobic end of the soap molecule interacts with water and the hydrophobic head with oil. This forms the micelle structure. this way the soap molecules form a micelle structure where one end of the molecule is on the side of the oil particle and the ionic end is on the outside. Our clothes get cleaned.
Soap Limits
Cannot be used in hard water. Soap reacts with salts of magnesium and calcium present in hard water to form an insoluble substance called scum.
This makes cleaning difficult.
Benefits of detergent
Can be used in both hard and soft water.
An insoluble substance is not formed.