Understanding Carbon and Its Compounds

Introduction: Why Carbon Is So Special

Look around you—your clothes, your food, petrol in vehicles, even you yourself—are made of carbon compounds. But why is carbon such a big deal in Chemistry?

Carbon is one of the few elements that can form millions of compounds—far more than any other element. This makes it the backbone of organic chemistry and even the building block of life.

Let’s understand how carbon works its magic and why we study it so deeply in Class 9.

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What Is Carbon?

Symbol: C
Atomic Number: 6
Electronic Configuration: 2, 4
Valency: 4 (because it needs 4 more electrons to complete its octet)

Carbon is a non-metal and is placed in Group 14 of the periodic table.

It forms covalent bonds by sharing electrons (not gaining or losing).

Why Can Carbon Form So Many Compounds?

There are two superpowers that make carbon so special:

1. Catenation

Catenation is the ability of carbon atoms to bond with other carbon atoms to form chains, branches, or rings.

Carbon can also form:

Single bonds (–)
Double bonds (=)
Triple bonds (≡)

So it’s like LEGO—it can join with others in many ways!

2. Tetravalency

Carbon has 4 valence electrons, so it can form 4 strong covalent bonds with other atoms like hydrogen, oxygen, chlorine, nitrogen, etc.

Types of Carbon Compounds

Carbon compounds are mainly organic and form covalent bonds.

1. Hydrocarbons

Hydrocarbons are compounds made only of carbon and hydrogen.

a. Saturated Hydrocarbons (Alkanes)

Have only single bonds
General formula: CₙH₂ₙ₊₂
Example: Methane (CH₄), Ethane (C₂H₆)

b. Unsaturated Hydrocarbons

Have double or triple bonds

Type	Example	Formula
Alkene	Ethene	C₂H₄
Alkyne	Ethyne	C₂H₂

2. Functional Groups

Functional groups are special atoms or groups attached to a hydrocarbon chain that give the compound its chemical properties.

Functional Group	Symbol	Example
Alcohol	–OH	Ethanol (C₂H₅OH)
Carboxylic Acid	–COOH	Acetic Acid (CH₃COOH)
Aldehyde	–CHO	Formaldehyde (HCHO)
Ketone	–CO–	Acetone (CH₃COCH₃)

Soaps and Detergents

Soaps

Made by saponification (reaction of fat/oil with alkali)
Work well in soft water
Are biodegradable

Detergents

Made from petrochemicals
Work even in hard water
Used in shampoos and washing powders

Combustion and Oxidation

Combustion

Carbon compounds burn in oxygen to give carbon dioxide + water + energy (heat/light)

Example:
CH₄ + 2O₂ → CO₂ + 2H₂O + Heat

Used in: Cooking gas, vehicles, candles

Oxidation

Carbon compounds can be oxidized to form alcohols or acids.

Example:
Ethanol → Acetic Acid (by oxidation)

Core Concepts Table

Concept	Meaning
Carbon	Non-metal, atomic number 6, valency 4
Catenation	Carbon atoms bond with other carbon atoms
Tetravalency	Forms 4 covalent bonds
Hydrocarbon	Compound of carbon and hydrogen
Saturated Compound	All single bonds
Functional Group	Group of atoms giving special chemical properties
Combustion	Burning in oxygen to give CO₂ and water

Frequently Asked Questions (FAQs)

Q1. Why does carbon form covalent bonds?
Because it cannot easily gain or lose 4 electrons, it shares them.

Q2. What’s the difference between alkanes and alkenes?
Alkanes have single bonds; alkenes have at least one double bond.

Q3. What is meant by catenation?
It’s the property of carbon to form long chains and rings by bonding with itself.

Q4. Why are soaps less effective in hard water?
Hard water contains calcium and magnesium ions that react with soap to form scum.

Q5. Give one use of ethanol.
Used in sanitizers and alcohol-based products.

Fun Facts

Diamond and graphite are both forms of carbon—but one is hard and shiny, the other is soft and black!
Dry ice is solid carbon dioxide.
Carbon dating helps scientists find the age of fossils.
Methane (CH₄) is the main gas in cooking fuel (LPG/PNG).
Your body is made up of about 18% carbon by weight!