The understandable notes-Carbon and its compound, Class 10, Part-1

 Why is Carbon important to us?

Before starting the chapter we should know why Carbon is important to us. You all know that salt is a compound and is used as spice in our food. Compounds of carbon are simply the fundamental of life. Life cannot exist without carbon and is compound. All living thing depends on carbon compounds for their existence. Think of carbon dioxide, carbohydrates, petrol, diesel, kerosene, all are carbon compounds. All biotic things consists of carbon. Medicines, books, wood, human, animals, depends heavily on carbon flow their survival and existence. 

The amount of carbon present in the earth’s

crust and in the 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.

( Dekho lenghty chapter hai to ise start krne se pehle ye to pata hona chahiye ki hum is chapter pr time kyo waste kr rhe hai. To jaise pichle chapter mai aapne compounds ke bare mai padha usi tarah is chapter mai bhi padhoge. Par pichle chapter mai humne ionic bonds ke bare mai padha aur yaha alag tarah ke compounds ke bare mai padhenge. Dekho carbon living beings ki fundamental requirement hai. Food, Clothes, Medicines, ye sab carbon based compounds se hi bane hai. Aur agar hum ek taraf bina carbon ke compounds ko rakhe aur dusri taraf carbon se bane hue compounds ko to carbon se bane hue compounds ki value un sabhi se kai guna jyada hongi. Ab aisa carbon ki kuch unique properties ki wajah se hota hai jo hum is chapter mai padhenge. Uske baad earth par kitna carbon present hai ye yaad rakh lena aur kis form mai hai ye bhi. Ab carbon ki importance sirf living tak hi khatam nhi hoti aap ne ye to suna hoga ki coal burn krke electricitybanayi jati hai to coal bho carbon hi hai. Iske alawa petrol, diesel, coaltar, vaseline jelly, kerosene, alcohol sab carbon ke hi compounds hi hai to ab samajh to gaye honge ki carbon kitna important hai.)

The branch of science which deals with the study of carbon and its compounds is called organic chemistry.

( Science ki jo field carbon aur uske compounds ke bare mai study krti hai use organic chemistry kehte hai. )

BONDING IN CARBON - THE COVALENT BOND

Why carbon cannot form ionic compounds 

Valency is the combining capacity of any atom. The atomic number of carbon is 6. Means it have two electrons in the K shell and 4 electrons in the valence shell. So to gain a noble gas configuration it have to gain or loose four electrons but both of them are not possible because of following reason-:

(i) It could gain four electrons forming C^4– anion. But it would be difficult for the nucleus with six protons to hold on to ten electrons, that is, four extra electrons.

(ii) It could lose four electrons forming C^4+ cation. But it would require a large amount of energy to remove four electrons leaving behind a carbon cation with six protons in its nucleus holding on to just two electrons.

( To sabse pehle to ye jaan lo ki carbon ionic bond kyo nhi banata. To carbon ka atomic number hota hai 6 jisse iske valence shell mai 4 electrons present hote hai. Ab ionic bond banane ke liye ye to carbon ko 4 electron gain krne honge ya to 4 electron loose krne honge pr carbon ye dono hi kaam nhi kr pata.

Agar carbon 4 electron gain krle to ek nucleus jisme 6 proton yani ki 6 positive charge hai uske liye 10 negative charge yani ki 10 electron ko hold krna impossible sa ho jaega jisse chemical instability hongi. Nucleus teen electron ki hi badi mushkil se hold kr pati hai aur yaha to 4 hai to isse se to baat nhi banegi.

Ek aur tarika hai ki carbon 4 electron ko loose krde jisse ye helium wali noble gas configuration attain kr le lekin ye bhi possible nhi hai. Chemical instability to baad ki baat hai 4 electron ko loose krne ka matlab bahut sari energy ko release krna padega.Itni energy release krna impossible hai. To kul milakar carbon kisi bhi tarah se ionic  bond to nahi bana sakta.)

COVALENT BOND- BONDING IN CARBON 

The bond formed by sharing of electrons is called covalent bond. They do it to achieve chemical stability. As carbon is incapable of forming ionic bond so it forms covalent bond. In this bond atoms doesn't transfer electrons but they share electrons to achieve chemical stability.  While sharing the shared electron is present in both atoms.  The shared electrons ‘belong’ to the outermost shells of both

the atoms and lead to both atoms attaining the noble gas configuration.

( Carbon ionic bond to bana nhi sakta to ab kre to kya kre. Chalo electrons ko transfer nhi kr sakte to isko share kr lete hai. Ab shared electron dono atoms ke valence shell mai consider hote hai. Yani ki electron ek hai aur unka effect do atoms pr hai. Isko covalent bond bolte hai aur ye ionic bond se kam strong hota hote hai. To carbon covalent bond banate hai. Ab dekhte hai ki kin kin molecules mai covalent bonding dikhti hai.)

Some molecules formed by covalent bonding.

The molecule of hydrogen (H2) is formed by covalent bond. Hydrogen contains one electron and needs one more to attain the noble gas configuration of helium. So it shares one electrons with other hydrogen atom as shown in the below diagram

In the diagram hydrogen atom is represented by a circle with its symbol in it. Electrons are represented by cross or dots. So as hydrogen atom contains only one electron there is only one cross in the diagram of atom. When both of the atoms combined to form a (H2) molecule. In the diagrammatic representation of hydrogen molecule the shared electrons is placed in the intersection of both spheres. Only valence electrons are represented in sphere and no other electron from completely filled shells are shown. A single bond is also shown by a line, similarly double bond is represented by two lines and triple bond by three lines.

( To dekho covalent bond sirf carbon nahi banata. Mostly non metals covalent bond banate hai. To iska sabse simple example hai hydrogen. Ab hydrogen ka atomic number hai 1 to iska matlab hai ki ek neutral hydrogen mai sirf 1 electron hi rahega aur ye to aapne padha hi hoga ki hydrogen atom ki form mai nhi molecule ki form mai exist krta hai jiska matlab ye hai ki ye ek aur hydrogen atom kai sath. To ab dekhte hai ki inhe diagram ki form mai kaise represent krte hai. To sabse pehle to aapko ghabrana nhi hai aur fir ye teen points yaad rakhna

Atom ko represent krenge sphere se jisme uska symbol hoga

Sirf valenceelectronsko hi represent krenge diagram ke andar.

Electron ko cross se or dots se represent krenge.

To is tarah humne hydrogen kai atom ko draw kiya. Aur fir humne two hydrogen atoms ko combine kiya. Ab jo electron share hoga vo dono atom ke sphere mai show hona chahiye. Agar atom ke paas bond banane kai baad bhi extra electrons bachte hai to hum unhe usi atom mai represent krenge lekin intersection vali jagah mai nhi. Kaise ye agle molecules ko dekh kar samajh aa jayega. Aur single bonds ko ek straightline se bhi represent krte hai. Ab jab questions kroge to baar baar sphere banakar to nhi dikhaoge na to isi liye ye ek convenient method hai.)

Molecule of Oxygen

The atomic number of oxygen is 8 and have 6 valence electrons in their outermost shell. So it have to share two more atoms with other oxygen atom to attain a noble gas configuration. The atoms and molecule is shown in the following diagram 

Oxygen atoms can also be shown as

Note that only valence electrons are shown in the diagram. The electrons which are shared is placed in the intersectional part of molecule.

( Ab jiase hydrogen ka molecule tha us se alag hai oxygen ka molecule. Oxygen ke valence shell mai 6 electrons hote hai. To apna noble gas configuration attain krne ke liye oxygen ko bas 2 electrons share krne padenge. To isi liye two electron dono atoms se intersection mai aayenge yani ki share honge. )

Now make nitrogen molecule as practice.

Molecule of methane

The compound made up of hydrogen and carbon are called hydrocarbons. Methane is the simplest hydrocarbon. One carbon is bonded to four different hydrogen atoms as shown in the following diagram.

The molecule can also be represented as 

Or simply as 

( Chalo hydrogen oxygen ke baad ab aate hai methane par. Methane simplest hydrocarbon hai. Ab ek baat yaad rakhna ki jaha jha carbon vaha vaha hydrogen. Carbon aur hydrogen bhai hai. Jab bhi carbon ke sath koi aur molecule ya atom laga ho aur carbon ki valency puri na ho rahi ho tab waha par hydrogen laga dena. Carbon aur hydrogen ka bahut gehra nata hai bas ye yaad rakhna. Ab aage nomenclature hoga to usme samajh aa jayega ki methane simplest molecule kyu hai. To ye to dekho koi tough kaam nhi hai electron dot structure banana. Bas kuch rules hai jo practice kroge to )

PROPERTIES OF COVALENT BOND

1. Formation of Covalent Bonds – Covalent bonds form when non-metal atoms share electrons to achieve a stable electronic configuration (octet rule). This sharing allows each atom to complete its outer shell. These bonds usually occur between elements like hydrogen, oxygen, nitrogen, and carbon. For example, two hydrogen atoms share electrons to form an H₂ molecule.

( Covalent bond electrons kai sharing se bante hai. Covalent bond generally non metals ke beech mai hi bante hai. Ab electrons share hote hai to is bond ke formation se ions nhi bante. Bas jyads kuch nhi ye hi to bata raha hu pichle part se.)

2. Types of Covalent Bonds – Covalent bonds can be classified based on the number of electron pairs shared. A single bond involves one pair of shared electrons (e.g., H₂), a double bond involves two pairs (e.g., O₂), and a triple bond involves three pairs (e.g., N₂). The more electron pairs shared, the stronger the bond.

( Dekho covalent bond single bonded bhi ho sakte hai, double bonded bhi aur triple bonded bhi. Quad bonded nhi ho sakte. Ab single bond se jyada strong double bond hota hai aur double bond se jyada triple bond. Ye to common sense ki baat hai.  )

3. Low Melting and Boiling Points – Covalent compounds have low melting and boiling points because the intermolecular forces between their molecules are weak. Breaking these forces requires less energy compared to ionic compounds. For example, substances like oxygen (O₂) and methane (CH₄) are gases at room temperature.

( Covalent bonds se bane hue compounds ka melting  aur boling point generally low hota hai hai kyonki molecules ka ek dusre se attraction force kam hota hai. Yaad rakhna molecule ke andar forces of attraction strong hota hai lekin dusre molecules se forces of attraction kam hota hai. Intermolecular ka matlab yehi hota hai ki dusre molecules se. Aur within the molecules ka matlab hai intramolecular force. )

4. Poor Conductors of Electricity – Covalent compounds do not conduct electricity in solid, liquid, or molten states because they lack free ions or electrons. Since they are made of neutral molecules, they cannot carry electric current. For instance, sugar and wax do not conduct electricity when dissolved in water.

( Ab dekho covalent bond electrons ke share hone se bante hai to ions banenge nhi. Ab ions nhi banenge to electricity kaise conduct hogi. Electricity ko flow hone ke liye free electrons ki jarurat hai aur free electron banane ke liye ya to electron ko gain karo ya to loose karo lekin covalent bond mai ye dono kaam nhi hote isi liye covalent compound bad conductorhote hai.)

5. Solubility – Covalent compounds are typically insoluble in water (a polar solvent) but dissolve in non-polar solvents like benzene or kerosene. However, some polar covalent compounds, like sugar, can dissolve in water. Non-polar compounds like oil do not mix with water.

( Dekho covalent compound water mai insoluble hote hai. Ab water ek polar solvent hai. Polar ka matlab hai ki electronegativity atoms ke beech mai equal nhi hai. Ab ye to pata hi hai ki like dissolves like. To jaise water ek polar solvent hai to usme dissolve bhi polar compound ho hoga. Haan to covalent compound water mai to nhi lekin non polar liquids jaise ki alcohols or kerosene mai soluble hote hai. )

6. Polarity – Covalent bonds can be polar or non-polar. In non-polar bonds, electrons are shared equally (e.g., H₂). In polar bonds, electrons are shared unequally, causing partial charges (e.g., H₂O). The polarity affects properties like solubility and boiling point.

( Covalent compound polar bhi ho sakte hai aur non polar bhi. Ab jaise hydrogen ka molecule hai to vo non polar hua kyonki dono atoms ki electronegativity same hai. To electron centre mai share honge. Lekin agar hydrogen ke sath oxygen ka bond banega to electronegativity same na hone ke karan ek dipole moment banega. Abhi iske bare mai itna deep jane ki jarurat nhi hai bas thoda bahut samajh lena. Baki physical state mai to kaise bhi exist kr sakte hai covalent compounds. Yani ki room temperature mai kisi bhi state mai exist kr sakte hai. To pehla part khatam hua. Ab agle part mai versatilenature padhenge. )