Radioactivity Flashcards
what are isotopes
forms of an element that have the same number of protons but different numbers of neutrons
how can we tell an atoms nucleus is stable
if it has a certain amount of neutrons for the amount of protons it has
as protons increase, what needs to happen to keep the nucleus stable
more neutrons are needed
what is decay
the process in which unstable atomic nuclei break apart or change, releasing radiation as they do so
what is radiation
energy carried by particles from a radioactive substance
when does an unstable nucleus emit an alpha particle
when it had too few neutrons
what is an alpha particle and what does it do to the element
a helium 4 nucleus, so it decreases the mass number by 4 and the atomic number my 2
when is a beta particle emitted
when the nucleus has too many neutrons
what is a beta particle and how does it change the element
– a high speed electron ejected from the nucleus as a neutron turns into a proton
and it increases the atomic number by 1
when are gamma rays emitted
after emitting an alpha or a beta particle, since the nucleus would be too hot
what are gamma rays
electromagnetic radiation from the nucleus
what is activity
the rate at which a source of unstable nuclei decay
what is activity measured in
Beqerels
Alpha penetrating power
stopped by skin or paper
beta penetrating power
stopped by 3mm aluminium foil
