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CARBON AND ITS ALLOTROPES
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CARBON AND ITS ALLOTROPES
S.NO.
CONTENTS
PAGE NUMBER
1
Introduction to carbon
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2
Allotropes of carbon
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3
Diamond
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DIGITAL TEXT 8 FOR CLASS9 9 Fullerene
4
Graphite
5 6
Carbon Nanotube
10
7
Summary
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CARBON AND
8 Let’s Assess ITS ALLOTROPES
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9
Extended activity
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Reference
14 MALAVIKA S. PHYSICAL SCIENCE BMMIITC KOTTARAKKARA
CARBON AND ITS ALLOTROPES
S. NO 1
CONTENTS Introduction to carbon
PAGE NUMBER 3
2 3 4 5 6 7 8 9 10
Allotropes of Carbon Diamond Graphite Fullerenes Carbon nanotube Summary Let’s assess Extended Activity Reference
5 7 8 9 10 12 13 13 14
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CAE
CARBON AND ITS ALLOTROPES
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CARBON AND ITS ALLOTROPES
Carbon is an element that is very familiar to you. This element also has a lot of specialities. Food, cloth, oils, soap, cosmetics, fuels, medicines, plant-animal body, paints, rubber, paper, plastic etc. are primarily carbon compounds.
INTRODUCTION TO CARBON Carbon is one of the fundamental non-metallic element Antoine Lavoisier named carbon from the Latin word ‘Carbo’, meaning coal. Carbon is the main component of coal. Coal is 3
a fossil fuel developed from the prolonged decomposition of buried plants and animals. So, it is clear that all life forms include carbon.
Symbol
C
Atomic number
6
Electronic Configuration
2, 4
Number of electrons in outermost shell
4
Valency
4
Metal / Non- metal
Non - metal
4
ALLOTROPES OF CARBON Allotropy is the existence of a chemical element in two or more forms, which may differ in the arrangement of atoms in crystalline solids or in the occurrence of molecules that contain different numbers of atoms. Carbon is capable of forming many allotropes because of its valency. A well-known crystalline form of carbon is diamond, followed by graphite and fullerenes. A large number of allotropes have been discovered and researched including ball 5
shapes and sheets. Larger scale structures of carbon include nanotubes, nanobuds and nanoribbon.
The phenomenon of the existence of an element in two or more forms has different physical properties, but identical chemical properties are called allotropy, and the different forms are called Allotropes
Carbon exhibits the phenomenon of allotropy and exists in the following two types of allotropic forms: I. Crystalline form of Carbon: Four Crystalline Allotropes of Carbon having well-defined crystal structures are: 1. Diamond 2. Graphite 3. Fullerenes 4. Carbon Nanotubes II. Amorphous allotropic forms of Carbon: Some important amorphous allotropic forms of Carbon are: 1. Coal 2. Coke 3. Wood charcoal 4. Animal charcoal 5. Sugar charcoal 6. Lampblack 7. Gas Carbon
CARBON IS KNOWN AS The magic element for everything on Earth. The king of elements 6
DIAMOND
Diamond is the purest crystalline allotrope of carbon. It has a number of carbons, linked together tetrahedrally. Each tetrahedral unit consists of carbon bonded to four carbon atoms which are in turn bonded to other carbons. This gives rise to an allotrope of carbon having a three-dimensional arrangement of C-atoms. Do you know why a Diamond is Hard? It is hard because breaking a diamond crystal involves rupturing many strong covalent bonds. Breaking covalent bonds is no easy task. This property makes this carbon allotrope the hardest element on earth. Physical Properties of Diamond • • • •
It is extremely hard It has a very high melting point It has a high relative density It is transparent to X-rays 7
• • • •
It has a high value of the refractive index It is a bad conductor of electricity It is a good conductor of heat It is insoluble in all solvents
GRAPHITE
It is also a pure form of carbon. This allotrope of carbon is composed of flat two-dimensional layers of carbon atoms which are arranged hexagonally. It is a soft, black and slippery solid. This property of graphite persists because it cleaves easily between the layers.
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Graphite is of two forms: α and ß. In α form, the layers are arranged in the sequence of ABAB with the third layer exactly above the first layer. In the ß form, the layers are arranged as ABCABC. Properties of Graphite: •
•
•
•
Since the layers are stacked over each other, this carbon allotrope can act as a lubricant. It also has metallic lustre which helps in the conduction of electricity. It is a very good conductor of both heat and electricity One of the most important properties of graphite is that it is used as a dry lubricant for machines at high temperature where we cannot use oil. Graphite is used to make crucibles which have the property that they are inert to dilute acids as well as to alkalis.
FULLERENES
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Fullerenes are the only pure form of Carbon because they do not have dazzling edges or surface bonds that attract other atoms, as in the case of graphite or diamond. Fullerene is a large spherical molecule of composition. The C60 fullerenes are also named Buckminsterfullerene or simply fullerene, in honour of American architect, Robert Buckminster. Fullerene is a saucer-ball-shaped molecule.
Uses of Buckminsterfullerene Buckminsterfullerene is used as lubricants, in drug delivery systems, and as catalysts. Fullerene is also used as a conductor. Some types of fullerenes are also used as an absorbent for gases. It is used in making cosmetic products.
CARBON NANOTUBE
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A Carbon nanotube consists of a two-dimensional array of hexagonal rings of Carbon, just as in a layer of graphite. The layer is then rolled into a cylindrical and capped at each end with half of a C60 fullerenes. Carbon nanotubes are very tough, about 100 times as strong as steel. These are electrically conducted only along the length of the tube
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SUMMARY Carbon (C), non-metallic chemical element although widely distributed in nature, is not particularly plentiful-it makes up only about 0.025 percent of Earth's crust-yet it forms more compounds than all the other elements combined. Carbon is 19th in order of elemental abundance in Earth's crust, and there are estimated to be 3.5 times as many carbon atoms as silicon atoms in the universe. The major topics discussed in the text are carbon, its properties, its allotropes and their uses, its compounds and their preparation, the property of catenation and the environmental processes like carbon cycle, global warming and greenhouse effect.
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LET’S ASSES What is meant by an allotrope of an element? Which allotropes of carbon occur in the solid state? Is diamond a good conductor of electricity?
EXTENDED ACTIVITY Construct the models of allotropes of carbon.
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REFERENCES https://en.wikipedia.org/wiki/Carbon# https://www.rsc.org/periodic-table/element/6/carbon https://www.embibe.com/exams/allotropes-of-carbon/ https://byjus.com/jee/allotropes-of-carbon/
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