Lecture 3 Flashcards
How is an isotope written?
N = chemical symbol
A = number of nucleons (protons and neutrons)
Z = atomic number
What is the equation for the total weight of the constituent parts of an atom?
W = total weight
Z = atomic number
A = number of nucleons (protons + neutrons)
mₑ = electron mass
mₚ = proton mass
mₙ = neutron mass
Define mass deficit
The difference between the sum of the parts of an atom (W) and the actual mass (M). This can be given by the equation W - M.
Define binding energy
The energy ascribed to the missing mass (mass deficit) in amu.
What is the equation for binding energy?
BE = binding energy
W = total weight
M = actual mass
Define binding energy per nucleon
The binding energy divided by the number of nucleons.
What is the equation for binding energy per nucleon?
E = binding energy per nucleon
W = total weight
M = actual mass
A = number of nucleons
Describe the shape of a plot of binding energy per nucleon against the number of nucleons
What is a Segre chart?
A diagram in which the number of protons in a nucleus is plotted against the number of neutrons.
The general trend of the Segre chart shows that _______ elements are alpha emitters.
Heavier
Where are beta emitters found on the Segre chart?
Above and below the band of stability (before the heavy alpha emitters). Beta+ is found above the band and beta- is found below the band.
Define alpha radiation
Ionising radiation that consists of alpha particles, emitted by some substances undergoing radioactive decay.
What is emitted in alpha decay?
A helium nucleus
What energy does an alpha particle have?
Energy in the order of 5 MeV
What are alpha particles stopped by?
Skin
What happens to an element when it undergoes alpha decay?
2 protons (and 2 electrons) are lost from the atom so the element is transmuted and changes into a different one.
What happens to an element when it undergoes beta decay?
The atomic number increases but the mass number decreases.
