1) State Heinsenberg’s uncertainty principle.
This principle states that it is impossible to measure simultaneously the
position and momentum of a small particle with absolute accuracy or certainty.
If an attempt is made to measure any one of these two quantities with higher
accuracy, then the other becomes less accurate. The product of uncertainty in
the position and uncertainty in momentum is always constant and is equal to or
greater than h/4p i.e.
Δx. Δp = h/4π
Where,
h is the Planks constant
Δx is the uncertainty in position
Δp is the uncertainty in momentum
D block elements
interview questions and answers
Chemical
thermodynamics interview questions and answers
2) Explain quantum numbers and the different types of quantum numbers present.
Quantum numbers are defined as a set of four numbers with the help of which we
can get complete information about all the electrons in an atom. Thus with the
help of these numbers we can get the information about the energy, location,
type of orbital occupied, shape of that orbital etc. Mainly there are four
types of quantum numbers. They are:
a. Principal Quantum Number: It is denoted by n. It tells us about the energy
level or shell in which the electron is present. The value of n can be
1,2,3,4…….etc. but it cannot be zero. It gives us the information about the
average distance of electrons from the nucleus, determines the energy of
electron in hydrogen atom and hydrogen like atoms. It also gives us the
information about the maximum number of electrons that a shell can have by
using the formula 2n2.
b. Azimuthal Quantum Number: It is denoted by l. Through this quantum number we
get to know the number of sub-shells present in the main shell. It also gives
information about the shapes of various shells present within the same
principal shell and also about the relative energies associated with these
sub-shells.
c. Magnetic Quantum Number: It is denoted by m. This quantum number explains us
that when a source producing spectral lines are placed in a magnetic field,
then each spectral line splits up into number of lines. This is also known as
Zeeman Effect.
d. Spin Quantum Number: The electron not only spins around the nucleus but also
about its own axis. The direction of electron spin is clockwise or
anti-clockwise. This quantum number helps to explain the magnetic properties of
the substance.
3) State different rules used for filling of orbitals in atoms.
a. Aufbau Principle: According to this principle, In the ground state of an atom
the electrons are added one by one to the various orbitals in order of their
increasing energy starting with the orbitals of lowest energy. The order of
increasing energies of various orbitals can be calculated by the (n+1) rule.
However if the (n+1) value of two different orbitals are same then the orbitals
with lower value of n has lower energy.
b. Pauli Exclusion Principle: This principle states that an orbital can have
maximum two electrons and these must have opposite spins.
c. Hund’s rule of maximum multiplicity: Electron pairing in p, d and f orbitals
cannot occur until each orbital of a given subshell contains one electron or is
singly occupied. This happens because electrons being identical in charge repel
each other when present at the same orbital.
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