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1
THE SOLID STATE
PROPERTY OF SOLID=it has definite shape size and
volume
...
Intermolecular force of attraction is very strong
...
Constituent particle are tightly bound
4
...
TYPES OF SOLID=there are two types of solid
...
Crystalline solid
2
...
crystalline solid= the solid in which long range
order of constituent particle
...
(2)
...
Amorphous solid = it has no form its shape is irregular
...
short range order of arrangement of constituent
particle and a regular repeating pattern is observed
over short distance
...
Anisotropic nature=this is due to different
arrangement of particle in different direction so it
change physical property such as electrical resistance,
refractive index etc
...
isotropic nature-arrangement of particle is same but
irregular in all direction this is due to no long range
order of arrangement so physical property are same in
all direction
...
molecular solid
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metallic solid
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These are further divided into three
categories
...
Non polar molecules-the molecules which have no
opposite pole it either be positive or negative
...
These molecules
are held by weak dispersion force or London force
...
These are generally liquid and sold at room
temperature
...
These molecules are held by strong dipole-dipole intraction
...
Melting point is higher than that of non polar molecule
...
HYDROGEN BONDED MOLECULAR SOLID-the molecules of such solid
contain polar covalent bond between H and F
...
2
...
These are
formed 3D arrangement of anion and captions bound by strong
electrostatic force (columbic force)
...
These do not conduct electricity in solid state
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3
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Metallic solid are held by metallic bond
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Malleable and ductile in nature
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Covalent solid-atoms are the constituent particle of covalent solid
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Non conductors of electricity
...
5
CRYSTAL LATTICE AND UNIT CELL:
Crystal lattice- 3d arrangement of constituent particle
in space
...
Feature of crystal lattice-
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1
...
2
...
3
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Unit cell- it is a smallest portion of crystal lattice
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Its dimension along three edge a, b and c
...
2
...
Unit cell broadly divided into two categories1
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Cent red unit cell
Primitive unit cell-when constituent particle parent only
corner position of unit cell, it is called primitive unit
cell
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Cent red unit cell are of three types1
...
2
...
7
3
...
Numbers of atom in unit cell1
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B C C U C-2atom
3
...
In this type of arrangement one sphere in contact with its two
neighbors
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Coordination number-2 in one dimension
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closed packing in two dimensions-this can be done in two
different ways
...
The second row may be place exactly above the first row
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2
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when atom are join they form hexagonal closed packed
structure
...
Arrangement in 3d
3d arrangement of constituent particle is take place in two way one
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1
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Hexagonal closed packed
1
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it is formed by by placing squre closed packed structure one over the
above
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horigental and vertical line aligen each other
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its lattice is AAA type
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its form simple cubic unit cell
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it form primitive unit cell
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three dimension hexagonal closed packed structure1
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As in cubic close packing, each sphere is surrounded by 12 other spheres
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Connecting the centers of the external 12 spheres gives Johnson solid
known
as the triangular orthobicupola (Steinhaus 1999, pp
...
237)
...
To verify this, construct a three-dimensional diagram containing a
hexagonal unit cell with three layers (Steinhaus 1999, pp
...
Both the top and the bottom contain six
spheres and one hemisphere
...
However, symmetry requires
that the piece of the sphere which is cut off is exactly balanced by an extra piece on the other side
...
The unit cell
(3)
The height is the same as that of two tetrahedra length
on a side, so
(4)
giving
11
(5)
(Conway and Sloane 1993, pp
...
Now that the Kepler conjecture has been established, hexagonal close
packing and cubic close packing, both of which have the same packing density of
known to be the densest possible packings of equal spheres
...
In
particular, if the spheres of cubic close packing are expanded until they fill up the gaps, they form a solid rhombic
dodecahedron(left figure above), and if the spheres of hexagonal close packing are expanded, they form a second
irregular dodecahedron consisting of six rhombi and six trapezoids (right figure above; Steinhaus 1999, p
...
The
latter can be obtained from the former by slicing in half and rotating the two halves
with respect to each other
...
Both the rhombic dodecahedron and squashed dodecahedron are space-filling polyhedra
...
hcp and ccp1
Lenhth of each edge=a and diagonal AC=b
In triangle ABC
AC2=b2=BC2+AB2=a2+a2=2a2
b =2a
if r is the radius of sphere than b = 4r=2a
a=2
...
To find the packing
efficiency we consider a cube with edge length a, face diagonal length b and cube diagonal as c
...
Metals
like
iron
and
chromium
fall
under
bcc
category
...
From the given figure
we can see that the particles are in touch only at the edges
...
4%
Examples falling under this category include metals like lithium and calcium
...
The occurrence of defects takes place when crystallization (the process of formation of
crystals) occurs at a very fast or at an intermediate rate
...
Basically, defects fall out in two forms:
Point Defect
Line Defect
16
Point Defect
Point Defect occurs when an atom is missing or is irregularly arranged in a crystal lattice
...
Image 1: Point Defect
Types of Point Defects
Point Defects are classified into two defects, namely:
Stoichiometric Defects
Nonstoichiometric Defects
Stoichiometric Defects
17
The defects due to which the stoichiometry of solids remains undisturbed are called stoichiometric
Defects
...
They are
also known as intrinsic or thermodynamic defects
...
This defect generally occurs
when we heat a solid
...
Interstitial Defect
Image 4: Interstitial Defect
When some extra constituent particles (atoms, molecules or ions) are acquainted in the interstitial
sites, the solid lattice is said to have an interstitial defect
...
Both vacancy and interstitial defects are depicted by non-ionic solids whereas in ionic solids these
defects occur in form of Schottky and Frenkel Defect
...
Schottky Defect
If in an ionic lattice equal number of cations and anions are missing from the lattice site, the lattice is
said to have Schottky defect
...
The compounds in which the size of cation and anion are nearly
equal tend to show this type of defect
...
Image 5: Schottky Defect
Frenkel Defect
Just like Schottky defect Frenkel defect is also observed in ionic solids
...
This dislocation of ion creates vacancy defect at its original site and interstitial defect at its new
20
position
...
Ionic solids in which there
are vast size differences between cation and ion tend to depict Frenkel Defect
...
They are of two types, namely:
Metal Excess Defect
Metal Deficiency Defect
Metal Excess Defect
Metal Excess Defect occurs in two ways:
Due to anionic vacancies
Due to presence of extra cations at interstitial sites
Due to anionic vacancies
Metal Excess Defect can be seen in alkali halides like NaCl and KCl
...
For
Example, when a NaCl crystal is heated in presence of sodium vapor, the sodium atoms are
deposited on the surface of the metal
...
To make this happen sodium loses electrons to become Na + and the
released electrons occupy the anionic vacancies
...
The anionic sites or vacancies which are filled by unpaired electrons are called F-centers and are
responsible for imparting a yellow color to the flame of NaCl
...
Due to presence of extra cations at interstitial sites
In this type of defect, extra positive ions and electrons occupy interstitial sites and maintain electrical
neutrality
...
For Example, in white zinc oxide on heating, it leaves
oxygen and becomes yellow
...
Metal Deficiency Defect
This defect occurs in metals containing less number of cations than anions
...
Due to unequal number of cations and anions the
metals obtained are non-stoichiometric
...
95O, Fe0
...
Image 6: Metal Deficiency Defect
Electrical propertyIntroduction to Electrical Properties
Apart from general physical characteristics like density and rigidity, solids depict another important
property called Conductivity
...
The values of conductivity are diverged and vary from 10-20 to 107
...
Types of Solids
22
Image 1: Types of Solids
On the basis of conductivity solids are classified into three types, namely:
Conductors
Insulators
Semiconductors
Conductors
The solids which allow current to flow through them very easily are called Conductors
...
Metals are generally good conductors of
electricity as their conductivity is generally near to 10 7 ohm -1 m -1
...
The conductivity
of insulators is majorly low with the range of 10 -20 to 10-10 ohm -1 m -1
...
23
Image 2: Common examples of conductors and insulators
Semiconductors
The solids in which the value of conductivity lies between to that of conductors and insulators are
known as Semiconductors
...
The value of conductivity lies between 10 -6 to 104 ohm 1
m -1
...
In solids conduction can be seen
in two ways:
Conduction in Metals
Conduction
Conduction in Metals
in
Semiconductors
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A conductor can conduct current in two ways either by the flow of electrons or by the flow of ions
...
Metals have the potential to conduct electricity in solid and molten phase
...
The atomic orbitals of metal atoms
are responsible for forming molecular orbitals
...
When the band is half-filled or partially filled the electrons can flow easily from one
band to another, thereby making the electron to flow under an applied electric field
...
Summarizing the points, the drawn conclusions are:
When the gap is high, electrons don’t jump from one band to another thereby the substance is
said to have low conductivity
When the gap is low, electrons can easily move from one band to another thereby the substance
is said to have high conductivity
Image 3: Energy Band Gap
Conduction in Semiconductors
25
Taking the case of semiconductors, the gap between valence band and conduction band is small
...
Electrical conductivity is directly proportional to temperature as
the electrons get more energy to move from one band to another
...
Some common examples of intrinsic semiconductors are silicon and germanium
...
To make
intrinsic semiconductor applicable we increase its conductivity with the help of doping
...
Doping is done in two ways, namely:
By adding electron rich impurities
By adding electron deficient impurities
By adding electron rich impurities
Silicon and germanium are present in group 14 of the periodic table with four valence electrons
each
...
When we dope silicon and
germanium with electron rich impurities like Phosphorus P the five electrons present in P form bonds
with Si and Ge
...
The semiconductors from this type of doping are also
called n-type semiconductors as the conductivity is enhanced due to the addition of negatively
26
charged
species
...
Out of four electrons present in silicon, three are used to form
covalent bonds with Boron and 1 electron is left unshared
...
An electron from nearby atoms
comes and fulfills the vacancy
...
Some are as follows:
Combinations of p-type and n-type semiconductors are used in manufacturing of electronic
components
Diode which is a general combination is utilized as a rectifier
27
Transistors which are used in detecting and amplifying sound signals are made by placing one
layer of semiconductor in between two similar semiconductor layers
Photo diode is widely utilized in converting light energy into electrical energy
Magnetic propertyMagnetic Properties of Materials
Magnetic Field: The magnetic field is an imaginary line of force around a magnet which enables
other ferromagnetic materials to get repelled or attracted towards it
...
Fig: Field Lines around a bar magnet
Properties of Magnetic field Lines
The Magnetic field lines by convention enter through the south pole and comes out of the north
pole
...
There is no chance of magnetic field lines intersecting with other
...
Magnetic Field Strength
Let us consider that a current carrying coil has produced a magnetic field H as shown in the diagram
below:
28
Then the value of H is given by,
H = nI/L(A/m)
Where n is the number of turns in solenoid and l is the length of the cylinder
...
It is given by
B = μ X H (Tesla or weber /m2)
Where μ is called the Permeability and is defined as the degree to which a substance gets
magnetized
...
Basically two types of
motions are associated with the electrons:
Motion of electrons in an orbit within the nucleus
...
The rotational force experienced by a magnet when placed in a magnetic field perpendicular to its
magnetic axis is defined as the Magnetic Moment of a Magnet
...
The net magnetic moment is zero in diamagnetic substancebecause when an
external field is applied to a diamagnetic substance then the magnetic moment of electrons is
aligned to the opposite direction of the applied field
...
30
Fig: Alignment of electrons opposite to magnetic field (H)
Paramagnetic Substance
In Paramagnetic material, there exists a little magnetic moment since the net magnetic moment is
not cancelled outcompletely
...
Example of paramagnetic materials
include Al, Cr, Mo,Ti,Zr
...
This phenomenon is also known as
Hysteresis and the plot between variations of magnetism with magnetic field is called Hysteresis
Loop
...
This temperature or point is known as Curie point or Curie Temperature
...
While in case of ferromagnetic material all the magnetic domains point
inthe same direction
...
MnO is
an
example
of
anti-ferromagnetism
Classification of elements in periodic table based
on Magnetic Properties
Frequently Asked Questions (FAQs)
33
Q1
...
A magnetic material is a material which under the influence of its magnetic field can attract or
repel other substances
...
Q2
...
The properties of magnet are:
The north pole of one magnet is always attracted to the south pole of other magnet and viceversa
...
Q3
...
A paramagnetic material is a substance which has little magnetic susceptibility
...
Example of paramagnetic materials include Al, Cr, Mo, Ti, Zr
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2