4.3 decay series
TRANSCRIPT
Alp
ha • Slow speed
• Relatively large • +2 charge• Can pick up loose
electrons to become a He atom
• Not much energy• Easy to stop• High ionising
ability• Low penetrating
ability
Bet
a • Faster than alpha• Small particle• -1 charge• Repelled by
electron cloud of other atoms
• More energy than alpha
• Do not ionise as readily as alpha
• More penetrating than alpha
Gam
ma • Moves at the
speed of light• No charge• Only interacts
when it directly hits a nucleus/electron, rare occurrence
• Low ionising ability
• High penetrating ability
Recap
Decay series Most radioactive isotopes do not decay directly to a
stable state, but rather undergo a series of decays until eventually a stable isotope is reached.
The daughter isotope may be stable or it may decay to form a daughter isotope of its own. The daughter of a daughter isotope is sometimes called a granddaughter isotope.
Parent isotope Daughter isotope Granddaughter isotope
Decay series Uranium-238, a naturally occurring isotope, is commonly
used to create fuel for nuclear reactors
Uranium-238 decays to stable Lead-206 after many radioactive decays
Gamma emissions aren’t represented in the following image
Decay series are important in planning for the management and disposal of radioactive materials and waste and for site cleanup
As radioactive decay progresses, the concentration of the original radioisotopes decreases, while the concentration of their decay products increases and then decreases as they undergo transformation
Decay series for Uranium-238From: http://commons.wikimedia.org/wiki/File:Decay_chain(4n%2B2,_Uranium_series).PNG
Story Time The importance of understanding decay chains is illustrated by the
creation of radon-222 during the decay of uranium-238 Radon is dangerous as it’s a gas, its decay emits alpha particles, and it has
a very short half-life (3.8 days) meaning it emits alpha particles at a high rate.
In the past scientists noticed a higher than expected level of lung disease in uranium miners. The miners worked long hours in enclosed spaces, surrounded by uranium ore and radon that seeped out of the rock.
It was expected to see problems related to the direct exposure to radiation. Instead, the predominant health problems were lung cancer and other lung diseases.
This led to regulations in two areas: improved ventilation in uranium mines and limits on the amount of radon ventilated from the mines to the ambient
air.
Thorium-232 decay series Create a series of nuclear equations showing the decay series
of Thorium-232 to Lead-208 using the following sequence of decays:
Alpha, beta, beta, alpha, alpha, alpha, alpha, beta, beta, alpha
Thorium-232 decay seriesAlpha, beta, beta, alpha, alpha, alpha, alpha, beta, beta, alpha
Thorium-232 decay seriesAlpha, beta, beta, alpha, alpha, alpha, alpha, beta, beta, alpha
Thorium-232 decay seriesAlpha, beta, beta, alpha, alpha, alpha, alpha, beta, beta, alpha
Thorium-232 decay seriesAlpha, beta, beta, alpha, alpha, alpha, alpha, beta, beta, alpha
