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Atomic Structure
Date: 03/04/2023
In 1810, English chemist Dalton proposed a model of the atom that was based on the
concept of particles that had a fixed mass and could not be broken down any further
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For example, the existence of
isotopes was challenged by Dalton's model, and no information was provided about the
internal structure of atoms
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First, he found that they should possess a negative charge
due to being deflected towards the anode
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Rutherford proposed the atomic model on the basis of the experiment with alpha
particles
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Rutherford's model suffered from some limitations,
the first of which was if electrons revolve around the nucleus they should experience
strong force of attraction towards the nucleus and since they are getting attractive force
towards a nucleus it means that the electrons should emit energy, emit light, and lose
the energy in the form of light
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Bohr suggested that
according to quantum mechanics at subatomic level energy is best thought of occurring
in discrete packets called photons
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Electrons are revolving around the nucleus but in fixed orbit it can not move
anywhere so the orbit has got a fixed radius
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According to the model of Niels Bohr, energy levels in atoms are discrete, with a fixed
energy gap between them
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Bohr's theory was based on the idea that
atoms are made up of small, hydrogen-like particles
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In these cases, the electron occupies both the lower energy level and the higher energy
level, and cannot make a transition between them
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It means that an electron is
jumping from higher energy level to a level n equal to 3
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The energies are or the wavelengths are of the order of 100
nanometers, and we can see that this complete series of lines is obtained as very
closely spaced lines and these are called as Lyman lines
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These are the
commonly observed series in the hydrogen spectrum
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In the early 19th century, Dalton proposed a model in which atoms were indivisible
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In the early 20th century, the model of quantum
mechanics was developed by Bohr and others
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However, borsari was the most successful of these theories, as it led to
new understanding of atomic structure and chemistry
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Psi square represents the probability of finding a particle in a particular distance
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However, psi square has got an important significance
that it represents the prognosis of finding a particle in a small volume
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Therefore, psi square is normalized by using a normalization condition
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The four quantum numbers which are important or which are necessary to
determine the position of the electron also specify the shape size and orientation of the
orbital in which the electron is moving
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Every value of n corresponds to a particular shell in the atom or the
main energy level
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They
carried out an experiment to prove the de broccoli concept so this is actually Davis and
German's experiment which could be used as a verification of the broccoli concept
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Davidson and German found if we consider the electron as
a wave then we can apply Bragg's equation 2 d sine theta is equal to n lambda where d
is the inter planar distance in the nickel crystal
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The intensity of the particle was
recorded by this detector goes on changing with increase in applied potential
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The wavelength of a material particle is inversely proportional to its linear momentum
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Planck's constant, h, is the constant that governs this
relationship
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Electrons behave as waves as well as particles and
have momentum and a wave with a wavelength
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Lambda is equal to lambda and lambda is equal to h upon m into v which is 6
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1 kg into 41
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Macroscopic particles do not have a de Broccoli concept because the uncertainty
principle states that it is not possible to measure simultaneously both the position and
momentum of a small moving particle with absolute accuracy or certainty
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2) There must be incident
radiation that gets reflected and enters the microscope
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4) If we
try to measure the velocity or momentum accurately, we will make a large error in the
position
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1 angstroms has the same uncertainty in its
position
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7) The same analogy is applied to a cricket ball; if its wave function
psi is a well behaved wave function, then it must meet four important conditions: first,
psi should be continuous in nature; second, its amplitude should continuously change in
a periodic manner; third, it should be a continuous function; and fourth, it should be
applicable to all particles of the same type
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If a
particle exists, it should exist in the entire space with single probability or the total
probability should be equal to 1
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In some cases
for certain functions, it is not possible to get such value of psi into psi star data
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In this case, we
can say that now the new wave function which is 1 by n into psi is a normalized wave
function
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The first quantum number among the four is the principal
quantum number which is not principle but it is principle there is the main quantum
number
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Every value of l corresponds to a sub shell like l is equal to 0 corresponds to subshell s
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sub shell
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If we place an atom in the
external magnetic fields, the angular momentum vector acquires 2 l plus 1 orientations
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For example, in s subshell l has a value of 0 so m will
have 12 plus 1 that is only one value which is equal to 0 which corresponds to 0
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The
azimuthal quantum number represents the subshell of an electron and the spin condom
number represents the direction of spinning of electrons that is clockwise plus 1 by 2
and minus 1 by two
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"Atomic Orbitals and their Effect on Chemical Reactions"
The region in space where there is more than 99 percent chance of locating the electron
is considered as an atomic orbital
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Orbital represents the movement of an electron around the nucleus in
three dimensional space
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orbits are either circular or elliptical in shape, which means electron is either revolving in
this fashion in a circular manner or in an elliptical manner that is called an orbit
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The size of an orbital is larger than the size of a node area on average
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There are three possible orientations of the p orbitals and we name them as p x p y and
p z
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If an
electron is present in p orbital it will be revolving around the nucleus in a dumbbell
fashion like an eight figure
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These five orbitals have dumbbell shape with two nodal planes and five possible
orientations
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This is about the shapes of
various orbitals coming to the Schrodinger wave equation for hydrogen atom
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So there are seven orbitals with different orientations
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If we take a projection of this over here x is
nothing but the distance between this point and the origin
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psi is a product of three
different wave functions, psi as a function of r theta and phi
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e is a constant
factor multiplied by the wave function psi so this is schrodinger wave equation
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As a result,
we should use a complete derivative and not the partial derivative because there is no
second variable available which has to be considered as a constant here there are three
variables and we are considering two variables as constants
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according to the bohr bury scheme the orbital with lower
value of n plus l has a lower energy
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the polys exclusion principle helps in constructing an atom by filling electrons in various
shells and subshells
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according to the bohr bury
scheme the orbital with lower value of n plus l has a lower energy
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The n plus l rule is over here
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For 3s sub shell, the value of n plus l is equal to 3 plus 0 so n plus 1 is
equal to n
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Filling of electrons
will follow this particular aspect: one's followed by when 1s is completely filled with two
electrons then it will go to 2p then 3s then 3p then 4s then 3d then 4 fe atomic number
26 electronic configuration is 1s to two s two two two p six three s two three p six four s
two and three d6
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That in degenerate orbitals
electrons are a field first singly and then the pairing takes place so that the multiplicity is
maximum
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The number of splittings, or multiplicity, is given by m = 2 into capital S plus 1
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This is the outcome of whom's rule of maximum multiplicity
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It says that degenerate orbitals will get field first singly and then pairing will
take place and according to extra stability principle half or completely fields options are
extra stable and so that configuration is preferred so d5 configuration will be more
stable as compared to d4 configuration
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The Balmer series is obtained when an electron
jumps from higher energy levels to second energy level
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If they are moving with
the same velocities, then we can calculate the wavelength of the Balmer line
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We can say n is the number of
the shell and the negative sign indicates that the energy is less by this particular factor
as compared to the energy of the free electron
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This is a negative sign for hydrogen atom
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So this is not a correct quantum number in this particular group
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There are three invalid sets of quantum numbers and there are two valid quantum
numbers
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If an electron is revolving in a p orbital which is having a dumbbell shape, what
is angular momentum? Let us see
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There is no minima in between two maximas coming to the 5 p y orbital
for phi u p by orbital we know that for 5 p subshell n equal to 5 and l equal to 1 and
hence n minus l minus 1 that is equal to number of planes comes out to be equal to phi
u minus 1 minus 1 equal to 3
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When an electron is placed in an orbital having l
equal to 2 then it can align in five different ways in one case there is no effect in second
case there will be plus half plus h cross plus twice h cross minus h cross and so on
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Li positive ion has

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the same energy as that of the fourth energy level of the atom so we are talking about
the fourth shell of the bohr
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When the electrons are removed in plus two oxidation state
the four s electrons are lost first and hence the electronic configuration will be fe2
positive with two less electrons as compared to this
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4 nanometers
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626 into 10
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This means that for every two waves of an electron that complete in a single
revolution around the third bore orbit, there are three waves that are equal to 2 pi r
divided by lambda
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Therefore, we can conclude that for
every three waves of an electron that complete in a single revolution around the third
bore orbit, there are only two waves that are equal to 2 pi r divided by lambda

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