·
Photon: A quantum of energy hu where h is called Planck's
constant and u is the frequency of the radiation.
·
Quantum: A "packet" of energy.
·
Principal Quantum Number: An integral number
which designates a particular quantised orbit.
·
Binding Energy (of an Electron): The minimum energy
that must be given to an electron to remove it from its orbit and take it to
infinity.
·
Lyman Series: The spectral series of the hydrogen
spectrum which lies in the ultraviolet region.
·
Balmer Series: The spectral series
of the hydrogen atom which lies in the visible region.
·
Paschen Series/ Brackett
Series/ Pfund Series: Spectral series of
the hydrogen atom which occur in the infra red region.
·
Ground State: The lowest energy state.
·
Ionisation Potential Energy: The energy required
to remove the electron from its ground state to infinity.
·
Atomic Number (Z): The number representing the number of
protons (or electrons) in an element.
·
Mass Number (A): The number representing the number of
nucleons (neutrons and protons) in an element.
·
Isotopes: Elements having the same atomic number but
different mass numbers.
·
Radioactivity: The nuclear phenomenon in which extremely
penetrating radiations are spontaneously emitted by elements of mass numbers
greater than 206.
·
Alpha (a) Particles: They are helium
nuclei (_{2}He^{4}).
·
bparticles: Electrons emitted by the nucleus during
radioactive decay.
·
g rays: Extremely penetrating electromagnetic
radiations emitted by the nucleus during radioactive disintegration.
·
Decay Constant (l): It is the ratio of the rate at which
the number of radioactive atoms disintegrate to the
number of atoms present at that instant.
·
HalfLife: The time required for a given number of
radioactive atoms to reduce to half of their initial value.
