Beta decay Flashcards
What are the two types of beta decay?
one where an electron is emitted
one where a positron is emitted
beta minus decay β
more commonly used in tests - if the question does not specify assume it is β- decay
a neutron in the nucleus of an unstable atom decays to become a proton and an electron
the proton stays within the nucleus, but the electron is emitted from the nucleus at high speeds (the - part of the β decay)
formula for beta minus decay
n -> p + e[-]
e.g.
[14][6]C -> [14][7]N + [0][-1]e
beta plus decay β+
a proton in the nucleus decays to become a neutron and a positron
the neutron stays in the nucleus and the β+ particle is emitted at a very high speed, carrying a + charge
formula for beta plus decay
p -> n + e[+]
e.g.
[22][11]Na -> [22][10]Ne + [0][+1]β
uses of beta decay (carbon-14 and positrons)
carbon-14 is an unstable isotope of carbon and emits β- particles
it has a half life of over 5700 years
it can be used for (radio)carbon dating, which involves finding the ages of materials that are thousands of years old
positrons can be used in hospitals to form images be the use of PET scans
Complete each equation and state whether it is a β- or β+ decay:
a) [131][53]I -> [131][54]Xe + ?
b) 23][12]Mg -> [23][11]Na + ?[
a) add [0][-1]β β- decay
b) add [0][-1]β β+ decay
Describe the changes that take place in the nucleus when it undergoes:
a) β- decay [2]
b) β+ decay [2]
a) a neutron turns into a proton and an electron is emitted
b) a proton turns into a neutron and a positron is emitted
How is a β- particle different from an electron that is found in a stable atom? [2]
a beta particle is an electron that is emitted from an unstable nucleus and an electron in a stable atom is found in shells orbiting the nucleus
Write a balanced equation for nickel-66 which undergoes β- decay [3]
[66][28]Ni -> [66][29]Cu + [0][-1]e
when an isotope is written out in the form element-x, what does x represent?
the mass number
total number of neutrons and protons
