Carbon and its Compounds Notes

i) Food, clothes, medicines, books, or many of the things that you listed are all based on this versatile element carbon.
ii). The earth’s crust has only 0.02% carbon in the form of minerals (like carbonates, hydrogencarbonates, coal and petroleum) and the atmosphere has 0.03% of carbon dioxide

Ionic Bonds:Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegativities
i) ionic compounds have high melting and boiling points
ii) conduct electricity in solution or in the molten state

which difficulty of Carbon to Form a Stable:
i) It could gain four electrons forming C4– 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 C4+ 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.

Covalent Bond:Such bonds which are formed by the sharing of an electron pair between two atoms are known as covalent bonds.
i) Have low melting and boiling point
ii) poor conductors of electricity

Types of Covalent Bond:

Single Covalent Bond: When a single pair of electrons are shared between two atoms in a molecule. For example; Cl₂, H₂ etc.

Double Covalent Bond: When two pairs of electrons are shared between two atoms in a molecule. For example; O₂, CO₂ etc.

Triple Covalent Bond: When three pairs of electrons are shared between two atoms in a molecule. For example; N₂ etc.

Allotropes of carbon The element carbon occurs in different forms in nature with varying physical properties.
i) Diamond
ii)graphite

Diamond

each carbon atom is bonded to four other carbon atoms forming a rigid three-dimensional structure
Diamond is the hardest substance

graphite

Each carbon atom is bonded to three other carbon atoms in the same plane giving a hexagonal array
One of these bonds is a double-bond, and thus the valency of carbon is satisfied.
Graphite structure is formed by the hexagonal arrays being placed in layers one above the other
graphite is smooth and slippery
Graphite is also a very good conductor of electricity unlike other non-metals

Lewis Dot Structure Lewis structures are also known as Lewis dot structures or electron dot structures.
These are basically diagrams with the element’s symbol in the centre. The dots around it represent the valence electrons of the element.
i)Lewis structure of clorine

Lewis structure of CO₂

Saturated Carbon Compounds the hydrocarbon in which the carbon connected by single bond Such carbon compounds are called saturated compounds
These are known as alkanes. General formula = C_nH_2n+2
Example

Unsaturated carbon Compounds These hydrocarbons have at least one carbon-carbon conneted by double or triple bond.

Alkenes the hydrocarbon in which carbon - carbon nennected by a double bond is called Alkenes General formula = C_nH_2n where n = 2,3,4….
Example
.

Alkynes the hydrocarbon in which carbon - carbon nennected by a triple bond is called Alkynes General formula = C_nH_2n−2 where n = 2,3,4….

Alkyl The group formed by the removal of one hydrogen atom from an alkene molecule is called an alkyl group

R-X Where
R = CH₃,C₂H₅
X = F , Cl, Br

Chains, Branches and Rings
The Structue of Carbon chains may be in the form of straight chains, branched chains or rings.

Structural isomers. The compound which have same moleculer formula but different sturcture are known as isomer

Homologous Series a series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series.

Charecteristics of Homologous Series
Member of Homologous Series have a same general formua
ii)Two adjecent Homologous Series differ by a –CH₂- unit
iii)Have a similar chemical properties
iv)As the molecular mass increases in any homologous series, a gradual change in physical properties so, melting points and boiling points increase with increasing molecular mass.

Functional Groups These heteroatoms confer specific properties to the compound, regardless of the length and nature of the carbon chain and hence are called fuctional group

Halo Group:- X (X be Cl, Br)The alkanes in which one or more than one hydrogen atom is replace by- X (F, CI, Br or I) are known as haloalkanes

. Alcohol -OH A compounds which containing – OH group are known as alcohols. For example C₂H₅OH ,C₃H₇OH etc.

Aldehyde group -CHO : A compounds which containing -CHO group are known as aldehydes. For example HCHO ,CH₃CHO, etc.

Ketone group -C=O: A compounds which containing -C=O group are known as ketones. For example, CH₃COCH₃) etc

Carboxyl group -COOH: All organic acids contain a carboxyl group -COOH so they are also called carboxylic acids. For example, CH₃CH₂COOH), etc.

Nomenclature of Carbon Compounds
Naming a carbon compound can be done by the following method –
i)Identify the number of carbon atoms in the compound.
(ii) In case a functional group is present, it is indicated in the name of the compound with either a prefix or a suffix (as given below).
(iii) If the name of the functional group is to be given as a suffix, the name of the carbon chain is modified by deleting the final ‘e’ and adding the appropriate suffix. For example, a three-carbon chain with a ketone group would be named in the following manner – Propane – ‘e’ = propan + ‘one’ = propanone.
(iv) If the carbon chain is unsaturated, then the final ‘ane’ in the name of the carbon chain is substituted by ‘ene’ or ‘yne’ as given below For example, a three-carbon chain with a double bond would be called propene and if it has a triple bond, it would be called propyne.

CHEMICAL PROPERTIES OF CARBON COMPOUNDS

CombustionThe process of burning carbon compounds in air to release a large amount of heat and light is called Combustion.
(i) C + O₂ → CO₂ + heat and light
(ii) CH₄ + O₂ → CO₂ + H₂O + heat and light
(iii) CH₃CH₂OH + O₂ → CO₂ + H₂O + heat and light

Note: Saturated hydrocarbons will generally give a clean flame

Note: unsaturated carbon compounds will give a yellow flame with lots of black smoke

Oxidation

Addition ReactionUnsaturated hydrocarbons add hydrogen in the presence of catalysts such as palladium or nickel to give saturated hydrocarbons.
ii). Catalysts are substances that cause a reaction to occur or proceed at a different rate without the reaction itself being affected

Substitution Reaction : The reaction in which one hydrogen of a hydrocarbon are replaced by some other atom in the presence of sunlight is called Substitution Reaction
CH₄ + Cl₂ → CH₃Cl + HCl (in the presence of sunlight)

Properties of Ethanol
i) Pure ethanol is a flammable
ii)colorless liquid
iii)boiling point of 78.5° C(351 k)
iv) lighter than water
V) No effect on any litmus paper

Uses:
i) Being a good solvent used to prepare the tincture of iodine and cough syrups.
ii)Ethyl alcohol is used in the manufacture of paints,dyes, medicines, soaps and synthetic rubber.

Harmful effect of Drinking alcohol:
i)When large quantities of ethanol are consumed, it tends to slow metabolic processes and to depress the central nervous system.
ii) Heavy drinking of alcohol make a person alcoholic this make finacially bankrupt

Reactions of Ethanol :
i) Reaction with sodium –
2Na + 2CH₃CH₂OH → 2CH₃CH₂O^–Na⁺ + H₂

Alcohols react with sodium leading to the evolution of hydrogen

Dehydrating:Reaction to give unsaturated hydrocarbon: Heating ethanol at 443 K with excess concentrated sulphuric acid results in the dehydration of ethanol to give ethene

Properties of Ethanoic Acid:
(i) Molecular formula: CH₃COOH
ii>common name acetic acid
iii)It miscible in water, alcohol and ether.
iv) Boiling point of ethanoic acid 118° C (391 k)

Esterification reaction:Esters are most commonly formed by reaction of an acid and an alcohol. Ethanoic acid reacts with absolute ethanol in the presence of an acid catalyst to give an ester

Note: Esters are sweet-smelling substances. These are used in making perfumes and as flavouring agents

saponification reaction: The alkaline hydrolysis of easter is known as saponification . it is used in the preparation of soap.

Reaction with a base: : ethanoic acid reacts with a base such as sodium hydroxide to give a salt and water
NaOH + CH₃COOH → CH₃COONa + H₂O

Reaction with carbonates and hydrogencarbonates:

Reaction with carbonates and hydrogencarbonates: :Ethanoic acid reacts with carbonates and hydrogencarbonates to give rise to a salt, carbon dioxide and water. 2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂

ii) CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂

SOAPS AND DETERGENTS:

SOAPS:

The molecules of soap are sodium or potassium salts of long-chain carboxylic acids

When animal fat or vegetable oil heat with concentrated sodium hydroxide solution gieves a soap

The ionic-end of soap dissolves in water while the carbon chain dissolves in oil. The soap molecules, thus form structures called micelles

Soaps are molecules in which the two ends have differing properties, one is hydrophilic, that is, it dissolves in water, while the other end is hydrophobic, that is, it dissolves in hydrocarbons.

one end of the molecules is towards the oil droplet while the ionic-end faces outside.
. The soap micelle thus helps in dissolving the dirt in water and we can wash our clothes clean

Limitation:
i) The reaction of soap with the calcium and magnesium salts, which cause the hardness of water to form an insoluble precipitate called scum
ii)need a larger amount of soap.

DETERGENTS:
Detergents are generally ammonium or sulphonate salts of long chain carboxylic acids
ii)The charged ends of these compounds do not form insoluble precipitates with the calcium and magnesium ions in hard water
iii) Detergents are usually used to make shampoos and products for cleaning clothes

Difference between soaps and detergents

Soaps	Detergents
These are sodium or potassium salts of long chain fatty acids.	These are ammonium and sulphonate salts of long chain fatty acids.
Ionic part of the soap is —COO–Na+	Ionic part of detergent is —OSO3-Na+.
Soap are not sutable in hard water	Detergent can be used in hard water
Soaps are biodegradable	Detergents are non-biodegradable