APPLIEDAPPLIEDPHYSICSPHYSICS

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Text BooksText Books

Book 1: Applied Physics by Dr. M. Book 1: Applied Physics by Dr. M. Chandra sekhar & Dr. Appala naidu, Chandra sekhar & Dr. Appala naidu, V.G.S. Book linksV.G.S. Book links

Book 2 Introduction to Solid State Physics Book 2 Introduction to Solid State Physics by C. Kittel, Wiley Eastern Ltd.by C. Kittel, Wiley Eastern Ltd.

Book 3Nanotechnology by Mark Ratner Book 3Nanotechnology by Mark Ratner and Daniel Ratner, Pearson Educationand Daniel Ratner, Pearson Education

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Suggested / Reference BooksSuggested / Reference Books

Book 1 Material science and Engineering Book 1 Material science and Engineering by V Raghavan PHI publishersby V Raghavan PHI publishers

Book 2 Material Science by M Arumugam, Book 2 Material Science by M Arumugam, Anuradha agenciesAnuradha agencies

Book 3Solid state physics by Ashcroft, Book 3Solid state physics by Ashcroft, Mermin, Thomson learningMermin, Thomson learning

Book 4Solid state physics by Gupta & Book 4Solid state physics by Gupta & Kumar,K.Nath & Co.Kumar,K.Nath & Co.

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Book 5: Applied Physics by Book 5: Applied Physics by P.K.Palaniswamy,Scitech P.K.Palaniswamy,Scitech Publications(India)Pvt.LtdPublications(India)Pvt.Ltd..

Book 6: Material Science by MS Vijaya & G Book 6: Material Science by MS Vijaya & G Rangarajan, Tata Mc Graw HillRangarajan, Tata Mc Graw Hill

Book 7: Applied Physics by K. Vijay Kumar & Book 7: Applied Physics by K. Vijay Kumar & T.Srikanth, S. Chand & Company Ltd.T.Srikanth, S. Chand & Company Ltd.

Book 8: Nano materials by A.K. Bandyopadhyay, Book 8: Nano materials by A.K. Bandyopadhyay, New Age International PublishersNew Age International Publishers

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UNIT-1UNIT-1Bonding in solidsBonding in solidsCrystal structuresCrystal structuresX-ray diffractionsX-ray diffractions

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APPLIED PHYSICSAPPLIED PHYSICS

CODE : 07A1BS05CODE : 07A1BS05

I B.TECHI B.TECH

CSE, IT, ECE & EEECSE, IT, ECE & EEE

UNIT-1: CHAPTER1UNIT-1: CHAPTER1

NO. OF SLIDES :31NO. OF SLIDES :31

77

S.No.S.No. ModuleModule LectureLecture

No. No.

PPT Slide PPT Slide No.No.

11 Introduction Introduction L1L1 88

22 Types of bonding Types of bonding L2L2 9-299-29

3.3. Estimation of Estimation of cohesive energy. cohesive energy.

L3L3 3030

4.4. Made lung constant. Made lung constant. L4L4 3131

UNIT INDEXUNIT INDEXUNIT-I UNIT-I

88

IntroductionIntroductionIntroduction:Introduction: Generally matter consists in three Generally matter consists in three states i.e., depending on their internal structure. states i.e., depending on their internal structure. Normally the states are solid state, liquid state, Normally the states are solid state, liquid state, and gaseous state. In solids stated as the closer and gaseous state. In solids stated as the closer collection of atoms result in bulk materials called collection of atoms result in bulk materials called solids. Solids are usually strong and exhibit solids. Solids are usually strong and exhibit elastic character. Solids can be broadly classified elastic character. Solids can be broadly classified as either crystalline or Non-crystalline. The as either crystalline or Non-crystalline. The arrangement of atoms in a solids is determined arrangement of atoms in a solids is determined by the character, strength and directionality of the by the character, strength and directionality of the binding forces. The bonds are made of attractive binding forces. The bonds are made of attractive and repulsive forces.and repulsive forces.

Lecture-1

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Types of BondingTypes of BondingAn atom consists of positively charged nucleus An atom consists of positively charged nucleus surrounded by negatively charged electron cloud. When surrounded by negatively charged electron cloud. When two atoms are brought closer there will be both attractive two atoms are brought closer there will be both attractive and repulsive forces acting upon. The value of the energy and repulsive forces acting upon. The value of the energy need to move an atom completely away from its need to move an atom completely away from its equilibrium position is a measure of “Bonding Energy “ equilibrium position is a measure of “Bonding Energy “ between them. between them.

This energy varies depending on the type of bonding.This energy varies depending on the type of bonding.

The bonds are made up of attractive and repulsive The bonds are made up of attractive and repulsive forces. Different charge distributions in the atoms give forces. Different charge distributions in the atoms give rise to different types of bondingrise to different types of bonding..

Lecture-2

1010

Bonds generally classified into five Bonds generally classified into five classes.classes.

1.1. Ionic bondingIonic bonding

2.2. Covalent bondingCovalent bonding

3.3. Metallic bondingMetallic bonding

4.4. Hydrogen bondingHydrogen bonding

5.5. Vander walls bonding.Vander walls bonding.

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Ionic Bonding:Ionic Bonding: An ionic bonding is An ionic bonding is the attractive force existing between the attractive force existing between a positive ion and a negative ion a positive ion and a negative ion when they are brought into close when they are brought into close proximity. These ions are formed proximity. These ions are formed when the atoms of different elements when the atoms of different elements involved lose or gain electrons in involved lose or gain electrons in order to stabilize their outer shell order to stabilize their outer shell electron configurations.electron configurations.

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Properties of ionic solids:Properties of ionic solids:

1.Ionic solids are crystalline in nature.1.Ionic solids are crystalline in nature.2.They are hard and brittle.2.They are hard and brittle.3.They have high melting and boiling 3.They have high melting and boiling

points.points.4.Since all the electrons are tightly 4.Since all the electrons are tightly

bound with the ions, ionic solids are bound with the ions, ionic solids are good insulators of electricity.good insulators of electricity.

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5.They are soluble in polar solvents and 5.They are soluble in polar solvents and insoluble in Non-polar solvents.insoluble in Non-polar solvents.

6.In an ionic crystal, a cation is surrounded by 6.In an ionic crystal, a cation is surrounded by as many anions as possible and vice-versa.as many anions as possible and vice-versa.

Examples of ionic solids:Examples of ionic solids:

NaCl, KCl, KBr, MgO, MgClNaCl, KCl, KBr, MgO, MgCl22,KOH, and,KOH, and

AlAl22OO33 are few examples of ionic solids. are few examples of ionic solids.

1414

Covalent Bonding:Covalent Bonding:

The arrangement The arrangement of electrons in an of electrons in an outer shell is outer shell is achieved by a achieved by a process of valence process of valence electron sharing electron sharing rather than electron rather than electron transfer.transfer.

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Properties of Covalent solids:Properties of Covalent solids:

1.Covalent bonds are directional. Change in the 1.Covalent bonds are directional. Change in the direction of the bond results in the formation of direction of the bond results in the formation of different substance.different substance.

2.Since different covalent solids have very much 2.Since different covalent solids have very much different bond strengths, they exhibit varying different bond strengths, they exhibit varying physical properties. For example, the diamond is physical properties. For example, the diamond is the hardest substance with very high melting the hardest substance with very high melting point. It is a very good insulator of electricity.point. It is a very good insulator of electricity.

3.Covalent solids are hard and brittle. They posses 3.Covalent solids are hard and brittle. They posses crystalline structure.crystalline structure.

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4.When compared with ionic solids, these solids 4.When compared with ionic solids, these solids have relatively low melting and boiling have relatively low melting and boiling points.points.

5.Pure covalent solids are good insulators of 5.Pure covalent solids are good insulators of electricity at low temperatures.electricity at low temperatures.

6.When covalent crystals are doped with certain 6.When covalent crystals are doped with certain impurities, they becomes semi-conductors.impurities, they becomes semi-conductors.

Examples of Covalent solids:S,I, Ge, Si, Examples of Covalent solids:S,I, Ge, Si, diamond and graphite.diamond and graphite.

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1818

Metallic Bonding:Metallic Bonding: The valence electrons The valence electrons from all the atoms belonging to the from all the atoms belonging to the crystal are free to move throughout the crystal are free to move throughout the crystal. The crystal may be considered as crystal. The crystal may be considered as an array of positive metal ions embedded an array of positive metal ions embedded in a “cloud” or “sea” of free electrons. in a “cloud” or “sea” of free electrons. This type of bonding is called metallic This type of bonding is called metallic bonding. bonding.

1919

Properties of Metallic solids:Properties of Metallic solids:

1.Metallic bonds hold the atoms 1.Metallic bonds hold the atoms together in metals.together in metals.

2.Metallic bonds are relatively weak.2.Metallic bonds are relatively weak.

3.Metallic solids are malleable and 3.Metallic solids are malleable and ductile.ductile.

4.Metallic bond is non directional.4.Metallic bond is non directional.

2020

5.They have high number of 5.They have high number of free electrons.free electrons.6.They possess high electrical 6.They possess high electrical and thermal conductivity.and thermal conductivity.7.Metals are opaque to light.7.Metals are opaque to light.Examples of metallic solids: Examples of metallic solids: Sodium, Copper, Gold, Silver, Sodium, Copper, Gold, Silver, Aluminum.Aluminum.

2121

Hydrogen Bonding:Hydrogen Bonding:Covalently bonded atoms often produce an Covalently bonded atoms often produce an

electric dipole configuration with hydrogen electric dipole configuration with hydrogen atom as the positive end of the dipole if atom as the positive end of the dipole if bonds arise as a result of electrostatic bonds arise as a result of electrostatic attraction between atoms, it is known as attraction between atoms, it is known as hydrogen bonding.hydrogen bonding.

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Properties of Hydrogen solids: Properties of Hydrogen solids:

1.The hydrogen bonds are directional. 1.The hydrogen bonds are directional.

2.The bonding is relatively strong as compared 2.The bonding is relatively strong as compared to other dipole-dipole interactions.to other dipole-dipole interactions.

3.Hydrogen bonded solids have low melting 3.Hydrogen bonded solids have low melting points.points.

4.Since no valence electrons are available in 4.Since no valence electrons are available in such solids they are good insulators of such solids they are good insulators of electricity.electricity.

5.They are soluble in both polar and nonpolar 5.They are soluble in both polar and nonpolar solvents.solvents.

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6.They are transparent to light.6.They are transparent to light.

7.Since elements of low atomic numbers form 7.Since elements of low atomic numbers form such solids, they have low densities.such solids, they have low densities.

8.When water is in the form of ice, hydrogen 8.When water is in the form of ice, hydrogen bond results in lower density; but when it bond results in lower density; but when it melts, it becomes more closely packed liquid melts, it becomes more closely packed liquid and hence its density increases.and hence its density increases.

Example of hydrogen bonded solids: Water Example of hydrogen bonded solids: Water molecule in the form of ice, ammonia molecule in the form of ice, ammonia molecules.molecules.

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Van der Waals(Molecular) Bonding:Van der Waals(Molecular) Bonding: Weak and temporary (fluctuating) dipole Weak and temporary (fluctuating) dipole

bonds between hydrogen are known as bonds between hydrogen are known as van der Waals bonding and they are van der Waals bonding and they are nondirectoinal. (OR)nondirectoinal. (OR)

Secondary bonding arising from the Secondary bonding arising from the fluctuating dipole nature of an atom with fluctuating dipole nature of an atom with all occupied electron shell filled is called all occupied electron shell filled is called van der waals bonding.van der waals bonding.

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Properties of Van der waals bonding:Properties of Van der waals bonding:

1.Van der waals bonds are nondirectional.1.Van der waals bonds are nondirectional.

2.Van der waals bonding is weaker than the 2.Van der waals bonding is weaker than the hydrogen bonding.hydrogen bonding.

3.Van der waals bonded solids have low melting 3.Van der waals bonded solids have low melting point.point.

4.Since no valence electrons are available, such 4.Since no valence electrons are available, such solids are good insulators of electricity.solids are good insulators of electricity.

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5.They are soluble in both polar and 5.They are soluble in both polar and non polar liquids.non polar liquids.

6.They are usually transparent to 6.They are usually transparent to light.light.

Examples of Van der Waals Examples of Van der Waals bonded solids:bonded solids: Solid neon, Solid Solid neon, Solid argon.argon.

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1.1. The mechanical, thermal, The mechanical, thermal, electrical and other properties of electrical and other properties of materials are related to chemical materials are related to chemical bonding and structure.bonding and structure.

2.2. The atoms/molecules in solids The atoms/molecules in solids are very strongly held together are very strongly held together by interatomic/ intermolecular by interatomic/ intermolecular forces called bonding in solids.forces called bonding in solids.

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3. 3. The force that holds atoms together is The force that holds atoms together is called bonding force. Under the bonded called bonding force. Under the bonded condition the potential energy is condition the potential energy is minimum.minimum.

4.The amount of energy required to separate 4.The amount of energy required to separate the atoms completely from the structure is the atoms completely from the structure is called cohesive energy. This energy is also called cohesive energy. This energy is also called energy of dissociation.called energy of dissociation.

2929

Primary Bondings have bond Primary Bondings have bond energies in the range of energies in the range of 0.1-10eV/bond. Ionic, Covalent and 0.1-10eV/bond. Ionic, Covalent and metallic bondings are the examples.metallic bondings are the examples.

Secondary Bondings have energies Secondary Bondings have energies in the range of 0.001-0.5eV/bond. in the range of 0.001-0.5eV/bond. Hydrogen bonding and van der waals Hydrogen bonding and van der waals bonding are the examples.bonding are the examples.

3030

Cohesive energy of NaCl molecule:Cohesive energy of NaCl molecule:Lecture-3

3131

The Madelung constant is a The Madelung constant is a function of crystal structure function of crystal structure and can be calculated from and can be calculated from the geometrical arrangement the geometrical arrangement of ions in the crystal.of ions in the crystal.

Lecture-4