CBSE Class 10 Chemistry Carbon And Its Compounds Worksheet Set H

Carbon and Its Compounds Notes Class 10 Science

Bonding in Carbon
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. If it were to gain or lose electrons –
(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.
Carbon overcomes this problem by sharing its valence electrons with other atoms of carbon or with atoms of other elements.

Covalent Bond
The bond formed by sharing a pair of electrons between two atoms are known as Covalent Bond. Carbon forms covalent bonds.

Lewis dot structures-
Lewis dot structures also called electron dot structures are diagrams that describe the chemical bonding between atoms in a molecule.
They also display the total number of lone pairs present in each of the atoms that constitute the molecule.
Note that only the valence shell electrons need to be depicted
The shared pair of electrons is said to constitute a single covalent bond between the two hydrogen atoms. A single covalent bond is also represented by a line between the two atoms
The two electrons contributed by each oxygen atom give rise to two shared pairs of electrons. This is said to constitute adouble bond between the two atoms.
Nitrogen atom in a molecule of nitrogen contributes three electrons giving rise to three shared pairs of electrons. This is said to constitute a triple bond between the two atoms.

Allotropes of Carbon
Different forms of an element that has same chemical properties but different physical properties are known as Allotropes. There are three allotropes of carbon- diamond, graphite and fullerene.

Graphite
*Graphite is made from weak van der waal forces.
*Each carbon atom is bonded with other three carbon atoms in order to form hexagonal rings.
*It serves as a good conductor of heat and electricity.
*It is used as dry lubricant for machine parts as well as it is used in lead pencils.

Diamond
*Diamond exists as a threedimensional network with strong carbon-carbon covalent bonds.
*Diamonds are hard in nature with high melting points.
*It shines in the presence of light and it is a bad conductor of electricity.
*The most common use of diamond is in making jewellery. It is also used in cutting and drilling tools.

Fullerene
*It is a hollow cage which exists in the form of a sphere.
*Its structure is similar to fullerene. But along with hexagonal rings, sometimes pentagonal or heptagonal rings are also present.

Versatile nature of carbon
Catenation is a property of carbon by which carbon atoms can link one another via covalent bond and can form long chains, closed rings or branched chains etc. Carbon atoms can be linked by single, double or triple bonds.
Carbon has a valency of 4 due to which it is known to have tetravalency. Due to this one carbon atom can bond with other 4 carbon atoms, with other atoms also such as Oxygen, Nitrogen etc.

Hydrocarbons

Compounds which are made up of carbon and hydrogen they are known as Hydrocarbons.
There are two types of hydrocarbons found - Saturated Hydrocarbons and Unsaturated Hydrocarbons.
SaturatedHydrocarbons consist of single bonds between the carbon atoms. For Example, Alkanes. Alkanes are saturated hydrocarbons represented by a formula, CnH2n+2.
UnsaturatedHydrocarbons are the one with double or triple bonds between the carb
Alkenes and Alkynes.
Alkenes are represented as CnH₂n whereas alkynes are represented as CnH2n-2. Some saturated hydrocarbons and unsaturated hydrocarbons are represented as

Homologous Series
Such a series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series.
The successive members of a homologous series differ by a –CH2- molecule and 14u by molecular mass.
As the molecular mass increases in any homologous series, a gradation in physical properties is seen. This is because the melting and boiling points increase with increasing molecular mass.
Other physical properties such as solubility in a particular solvent also show a similar gradation.

Nomenclature of Carbon Compounds
The names of compounds in a homologous series are based on the name of the basic carbon chain modified by a “prefix” “phrase before” or “suffix” “phrase after” indicating the nature of the functional group.

Naming a carbon compound can be done by the following method-
(i) Identify the number of carbon atoms and longest chain in the compound. A compound having three carbon atoms would have the name propane.
(ii) In case a functional group is present, it is indicated in the name of the compound with either a prefix or a suffix.
(iii) If the name of the functional group is to be given as a suffix, and the suffix of the functional group begins with a vowel a, e, i, o, u, then 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 in Table 4.4. 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.

Important Carbon Compounds: Ethanol and Ethanoic Acid Ethanol -
Ethanol is a volatile liquid with low melting point. It reacts with sodium to form sodium ethoxide.

Reaction of ester with strong base is used to form soap. This is known as reacts with strong base to form sodium acetate and water.
NaOH + CH₃COOH + CH₃COONa + H₂O

Soaps and Detergents

* Sodium or potassium salt of carboxylic acid is known as Soap. * They work most effectively in soap water.

* Detergents are sulphonate or ammonium salt of a long chain of carboxylic acid. * They can work effectively on soft as well as hard water.

Cleansing Action of Soaps and Detergents
Cleansing action of soaps and detergents is due to the ability to minimize the su emulsify oil or grease and to hold them in a suspension of water. When soap dissolves in water, it forms soap anions and soap cations.
The hydrophobic part of soaps and detergents are soluble in grease and the hydrophilic part water.

Soap and Micelle Formation
When dirt and grease are mixed with soap water, soap molecules arrange them in tiny clusters known as Micelle.
The hydrophilic part sticks to the water and forms the outer surface of the micelle and the hydr binds to oil and grease.
Esterification: Esters are sweet-smelling substances. These are used in making perfumes and as flavouring

agents.
Esters react in the presence of an acid or a base to give back the alcohol and carboxylic acid. This r known as saponification because it is used in the preparation of soap.

 

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