atomic structure Flashcards
charge of an electron
1.6 x 10^-19 C
mass of an electron
9.1 x 10^-31 kg
Avagadro no.
6.023 x 10^23
mass of proton
1.672 x 10^-27 kg
mass of neutron
1.675 x 10^-27 kg
no. of protons =
atomic no.
no. of neutrons =
mass no. - atomic no.
mass no. =
no. of protons+no. of neutrons
what is a black body?
an ideal body that emits and absorbs radiations of all
frequencies.
what is an atomic orbital?
it is defined as three-dimensional space around the
nucleus, where the probability of finding electrons is
maximum.
what is the Zeeman effect?
the splitting of one spectral line in external magnetic
field into several fine lines.
what is the stark effect?
the splitting of one spectral line in external electric
field into several fine lines.
explain Pauli’s exclusion principle
no 2 electrons in an atom can have the same set of
all 4 quantum numbers.
OR
an orbital can accommodate a maximum of 2 electrons
only with the opposite spin.
what is the Aufbau principle?
in the ground state of atoms, the orbitals are filled with
electrons in the order of their increasing energies.
what is Hund’s rule?
in the degenerate orbitals pairing of electrons take place, when each orbital is filled with one electron.
OR
in the degenerate orbital, first, the orbitals are half-filled
and later paired up.
explain Heisenberg’s uncertainty principle?
it is impossible to determine the exact position and momentum of a fast-moving particle like an electron simultaneously and accurately.
how is an orbital possible?
an orbital is possible if the azimuthal quantum no.
is less than principal quantum no.
explain the particle nature of electromagnetic radiation
particle nature of electromagnetic radiation can be explained with the help of black body radiation. the atoms and molecules could emit and absorb radiation only in discrete quantities called quantum and not in a continuous manner.
what series of lines are absorbed in hydrogen spectra
Lyman - ultraviolet Balmer - visible Paschen - near-infrared Brackett - infrared Pfund - far-infrared
what are the main features of the quantum mechanical model of an atom?
- energy of electron in atoms is quantised.
- the existence of quantised energy levels is a direct result of the wave properties of electrons.
- the path of an electron in an atom can never be determined or known accurately. therefore the probability of finding an electron arises.
- an atomic orbital wave function represents the state of an electron in an atom.
- the region around the nucleus where the probability of finding an electron is max is known as an orbital.
velocity of electron=
1.6 x 10^6 m/s
planck’s constant (h)=
6.625 x 10^-34
wavelength of the electron(lambda)=
4.55 x 10^-10 m
lambda=
h/mv