The Solid State: Class 12 Chemistry NCERT Chapter 1

Key Features of NCERT Material for Class 12 Chemistry Chapter 1 – The Solid State

Introducing you all to the 12th Chemistry, In the first chapter: The Solid State, you will learn about solid and its properties like the properties of solids depend upon the idea of constituent particles.

(The Solid State: Class 12)

This bit of substance manages a strong state. As a matter of first importance, we think about fluids and gases as liquids. This is a direct result of their capacity to stream. Also, this smoothness is conceivable in light of the fact that their particles are permitted to move about. Also, the places of constituent particles in solids are fixed, and they can simply sway. Thus, this outcomes in unbending nature in solids.

 Besides, the properties likewise depend upon the coupling powers which work between the constituent particles. In addition, the connection between’s the properties and structure encourages the revelation of new strong materials. Generally imperative, various game plans of particles can be made with the strong state. Along these lines, strong state notes will come helpful while considering this subject.

Smart correction notes

Strong: Solid is a condition of issue where the comprising particles are arranged minimalistically. The constituent particles could be iotas, atoms, or particles.

Properties of solids:

They have distinct mass, volume, and shape.

They are compressible and inflexible.

Intermolecular separations are very short, and consequently the intermolecular powers are solid.

Their constituent particles have a fixed position. Sand can simply waver about their mean positions.

Grouping dependent on the game plan of constituent particles: 

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Properties of glasslike solids:

They have an unequivocal mathematical shape.

 They have a long-run demand.

 They have a sharp liquefying point.

 They are anisotropic; for instance, their physical properties show various qualities when estimated alongside various bearings in a similar precious stone.

 They have unmistakable warmth of combination.

 They are called genuine solids.

 Right when cutting with a sharp-edged apparatus, they split into two pieces, and the as of late created surfaces are plain and smooth.

(The Solid State: Class 12)

Polymorphic structures or polymorphs:

The unmistakable glasslike types of a substance are known as polymorphic structures or polymorphs, for example, graphite and gem.

Attributes of formless solids:

 They have an unpredictable shape.

 They have a short-run demand.

 They constantly mellow over the organization of temperature.

 They are isotropic in nature. For instance, their physical properties are the equivalent all over.

 Exactly when cut with a sharp-edged instrument, they split into two pieces with unpredictable surfaces.

 They don’t have a particular warmth of combination.

 They are called pseudo solids or supercooled fluids. This is on the grounds that they will in general stream, however gradually.

Kinds of glasslike solids:

 Sub-atomic Solids

 Particles: Molecules

 Constituent Particles: IonsB. Ionic Solids

 Holding/Attractive Forces: Coulombic or Electrostatic

Electrical Conductivity: Insulators in a strong state however leads in the liquid state and watery arrangements

 Physical Nature: Hard however weak

 Softening Point: High MP

 Models: ZnS, MgO, and so forth

 Metallic Solids

 Including Particles: Positive particles in an ocean of delocalized electrons

 Compound Bonding: Metallic holding

 Conductivity Conductors in the strong state just as in liquid state

 Physical Nature: Hard however moldable and bendable

 Softening Point: Fairly high

 Models: Fe, Cu, Ag, Mg

Covalent or NetworkSolids

 Constituent Particles: Atoms

 Holding/Attractive Forces: Covalent holding

 Electrical Conductivity: Conductors in a strong state just as in liquid state

 Physical Nature: Hard however moldable and bendable

 Softening Point: Fairly high

 Models: , (quartz), SiC, C (valuable stone), C(graphite 

Gem lattice: A customary masterminded course of action of constituent particles in three measurements is known as a precious stone lattice. 

(The Solid State: Class 12)

Lattice focuses: the fixed situations on which the constituent particles present are called lattice focuses or lattice locales. At the point when rehashed time and in 3 measurements, a social occasion of lattice focuses gives the total precious stone lattice.

Unit cell: It is portrayed as the littlest rehashing unit in space lattice, which, when rehashed time and, makes the total lattice. The precious stone can contain a boundless number of unit cells in it.

Variables which portray a unit cell: Dimensions of every unit cell along the three edges, a, b, and c: these edges could be commonly opposite.

The tendency of the edges to one another: the edge between the edges means this, and respectively.is the point between the edges b and c, is the edge between the edges an and c and is the edge among an and b. 

Seven gem frameworks:

for, Cubic: ===90° ,a=b=c

for, Tetragonal: ===90° ; a=bc

for, Orthorhombic: ===90°; ABC

for, Monoclinic: ==90°,90°; abc

for, Hexagonal: ==90°,=120°; a=bc

for, Rhombohedral or three-sided: = =90°;a=b=c

for, Triclinic: 90°;abc

Sorts of unit cells:

Crude or straightforward unit cells have particles present precisely at its corners.

Centered unit cells are those unit cells where in any event one constituent molecule is present at positions notwithstanding those present at the corners.

Kinds of centered unit cells:

A face-centered unit cell comprises of one constituent molecule present at the focal point of each face and those present at the corners.

Body-centered unit cell: It comprises of one constituent molecule present at its body place notwithstanding the particles present in corners.

End centered unit cell: It includes one constituent present at the focal point of any of the two inverse sides and having particles at the corners too.

Number of particles at various lattice positions: 

(The Solid State: Class 12)

A face-centered unit cell comprises of one constituent molecule present at the focal point of each face and those present at the corners. 

Body-centered unit cell: It comprises of one constituent molecule present at its body place notwithstanding the particles present in corners. 

End centered unit cell: It contains one constituent present at the focal point of any of the two inverse sides and having particles at the corners too.

The quantity of iotas in various unit cells:

Crude unit cells have 1atom.

Face centered unit cell has three iotas.

Body-centered unit cells have 2atoms.

Coordination number: Coordination number is the amount of closest neighbors of a molecule.

Close pressed structures:

Close squeezing in two measurements: It is produced by stacking the lines of personal stuffed circles in two different ways: I) Square close squeezing and ii) Hexagonal close squeezing.

Close squeezing in three measurements: They can be gotten by stacking the two-dimensional layers one over the other. It tends to be accomplished in two different ways: I) Square close stuffed layers and ii) Hexagonal close squeezed layers.

Square close squeezing: Here, the circles of the second line item put precisely over those of the primary line. Along these lines the circles are balanced on a level plane just as vertically. The course of action is an AAA type. Four is the coordination number,

• Hexagonal close-pressing: Here, these circles of the bond lines are put over the first in a stunned manner so that its circles fit in the downturn of the primary line. The course of action is ABAB type. 6 is the coordination number. 

Three-dimensional pressing got from 2D square close-stuffed layers: In this, the circles of the upper layer are set decisively over the primary layer, with the end goal that the circles of the layers are accurately balanced on a level plane and vertically. It has an AAAA type design. The lattice is a basic cubic lattice. 

(The Solid State: Class 12)

Three-dimensional close pressings from two dimensional hexagonal tight, stuffed layers: There are two stages required as: 

Putting these bond layer over the main layer

Putting the third layer during the time layer

There emerge two prospects: 

  

• Covering the octahedral voids: In this, octahedral voids of these bond layers might be secured by the circles of the third layer. It offers ascend to the ABCABCABC type design. This 3D structure is known as a cubic close-stuffed structure or face-centered cubic structure. The coordination number is 12. Model: Cu, Ag.
• Kinds of voids:
• Octahedral void-It is formed at the middle when six circles have taken an interest as an octahedron.   
• In hexagonal close squeezing or cubic tight squeezing game plan, the octahedral and tetrahedral voids are present. The amount of octahedral voids present in a lattice is comparable to the amount of close squeezed particles. The amount of tetrahedral voids is double the amount of octahedral voids.

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For instance:

If the aggregate sum of close squeezed particles = n

All out Number of particles present in octahedral voids = n

At that point, the amount of particles present in tetrahedral voids = 2n

Squeezing profitability: It is the level of all out space required by constituent particles (iotas, atoms, or particles).

Squeezing efficiency for face-centered unit cell =74%

Squeezing efficiency for body-centered cubic unit cell =68%

Squeezing efficiency for the cubic unit cell =52.4%

Range proportion in an octahedral void: For a particle to have an octahedral void, its span ought to be 0.414 occasions more than the sweep of the circle

Span proportion for tetrahedral void: For an iota to have a tetrahedral void, its range must be 0.225 occasions the sweep of the circle.

The thickness of a unit cell is equivalent to the thickness of the substance. Connection between span of constituent particle(r) and edge length(a):

Basic cubic unit cell: a=2r

Face centered unit cell: a=

Body centered unit cell: a=

Volume of a unit cell=(edge length)3=

Basic cubic unit cell: Volume=

Face centered unit cell: Volume=

Body centered unit cell: Volume=

Number of particles in a unit cell(z):

Basic cubic unit cell: z = 1

Face centered unit cell: z = 4

Body centered unit cell: z = 2

Thickness of unit cell =

Precious stone imperfections are fundamentally anomalies in the game plan of constituent particles.

Kinds of imperfections:

Point deserts Point surrenders are the inconsistencies or deviations from perfect course of action around a point or an iota in a translucent substance.

Line deserts Line surrenders are the inconsistencies or deviations from the perfect association in whole lines of lattice focuses. 

Various kinds of point surrenders: 

• Various sorts of stoichiometric deformities for non-ionic solids: 
• Interstitial deformity: A gem is said to have an interstitial mistake when some constituent particles (iotas or atoms) include an interstitial site. This imperfection brings about an expansion in the thickness of the substance.
• Various kinds of stoichiometric imperfections for ionic solids:
• Frenkel or disengagement deformity: In this imperfection, the littler molecule (normally cation) is disjoined from its run of the mill site to an interstitial site. It makes an opportunity to desert a novel site and an interstitial deformity at another area. It doesn’t change the thickness of the strong. Frenkel deformity is appeared by the ionic substance wherein there is a huge differentiation in the size of particles. It incorporates ZnS,AgCl,AgBrand AgI. 
• Various kinds of non-stoichiometric deformities: 
• Metal inadequacy: This deformity emerges as a result of the nonattendance of metal particles from its lattice locales. The electrical lack of bias is kept up by a neighboring molecule having a higher positive charge.
• Purposes behind the reason for metal abundance deformity: 

 a) Anionic opportunities: A compound may have an additional metal molecule if the negative molecule is missing from its lattice site. This vacant lattice site is known as an opening. To keep up electrical impartiality, this site is included by an electron. The gap required by a particle is called f-focus or Farbenz enter focus. The F-focus is answerable for the shade of the compound.

 b) Presence of extractions: A compound is said to have additional cations if a cation is present in the interstitial site. An electron is present in the interstitial site to keep up electrical impartiality.

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Order of solids dependent on their electrical conductivities:

a) Conductors: The solids with conductivities going between to are called conductors.

b) Insulators: These are the solids with uncommonly low conductivities stretching out between to. to.

 c) Semi-conductors: These are the solids with high conductivities in the middle range. to.

b) In separators, the electrons can’t energize the conduction band.

c) For the situation of semiconductors, the distinction in groups is little. Accordingly, a few particles may jump to the conduction band and give some conductivity. The electrical conductivity of semiconductors increments with the ascent in temperature. 

Sorts of semiconductors:

 a) Intrinsic semiconductors: These are those semiconductors wherein the no-no opening is little. Simply a few electrons may bounce to the conduction band and give some conductivity. They have low electrical conductivity. Model: Silicon, germanium.

 b) Extrinsic semiconductors: When a suitable contamination is added to an inborn semiconductor, it is called outside semiconductors. Their electrical conductivity is high.

Doping: The way toward including a fitting measure of appropriate polluting influence to build the conductivity of semiconductors is known as doping.

a) The n-type semiconductors: They are confined when silicon is doped with electron-rich debasement like social occasion 15 components. The expansion in conductivity is a result of the contrarily charged electrons.

 b) The p-type semiconductors are encircled when silicon is doped with an electron-insufficient polluting influence, such as social affair 13 components. The expansion in conductivity is a result of the decidedly charged gaps.

Sorts of extraneous semiconductors:

Doping: The way toward including a fitting measure of reasonable debasement to expand the conductivity of semiconductors is known as doping.

a) The n-type semiconductors: They are confined when silicon is doped with electron-rich polluting influence like get-together 15 components. The expansion in conductivity is a result of the adversely charged electrons.

b) The p-type semiconductors are confined when silicon is doped with an electron-lacking contamination, such as social event 13 components. The expansion in conductivity is a result of the decidedly charged openings.

Diode: It is a mix of n-type and p-type semiconductors and is utilized as a rectifier.

Semiconductors are built by sandwiching a layer of one sort of semiconductor between two layers of the other semiconductor. The npn and pnp sort of semiconductors are utilized to escalate radio or sound signs.

The 12-16 exacerbates: These mixes are formed by the mix of social event 12 and get-together 16 mixes. They have an ordinary valency of 4.Examples – ZnS, CdS, CdSe, and HgTe.

The 13-15 exacerbates: These mixes are formed by the blend of social affair 13 and get-together 15 mixes. They have a typical valency of 4.Examples – InSb, AlP, and GaAs.

Every substance has some attractive properties related with it. The origin of these properties lies in the electrons.

Each electron in a particle carries on like a magnet. Its attractive second starts from two kinds of movements:

(I) its orbital movement around the core and

(ii) it’s turn around its hub.

Grouping of substances dependent on their attractive properties:

Paramagnetic substances: These are those substances which are sadly pulled in by the attractive field. It is a direct result of the nearness of at any rate one unpaired electron.

Diamagnetic substances: An attractive field weakly repulses diamagnetic components. Diamagnetism is appeared by those substances where all the electrons are matched, and there are no unpaired electrons.

Ferromagnetic substances: These are substances that are pulled in each effectively by an attractive field.

Hostile to ferromagnetic substances have a proportional number of equal and antiparallel attractive dipoles bringing about a zero net dipole second.

Ferromagnetic substances: They have a conflicting number of equal and antiparallel attractive dipoles bringing about an at dipole second.

Questions

Q: A compound formed by components An and B takes shape in the cubic structure where An iotas are at the edges of a strong shape, and B particles are at the face habitats. The formula of the compound is

AB3

Stomach muscle

A3B

A3B3

Sol: The right answer is “A.” The count will be as per the following.

Number of An iotas = 1/8 × 8 = 1

Number of B iotas = 1/2 × 6 = 3

(The Solid State: Class 12)