half lives and the random nature of radioactive decay.

Question 1

what does the random nature of radioactive decay do?

Answer 1

makes it impossible to predict which nucleus will decay next.

Question 2

with a large enough number of nuclei what is it possible to do?

Answer 2

predict how many will decay in a certain time period.

Question 3

what is the half life of a radioactive isotope?

Answer 3

average time it takes for half of the nuclei to decay.
time it takes for the count rate or activity of a sample containing the isotope to fall to 50% of its original value.

Question 4

if a count rate takes 25 minutes to fall from 80 to 40 what is its half life?

Answer 4

25 minutes.

Question 5

what doesn’t the half life of a particular radioactive isotope do?

Answer 5

doesn’t change.

Question 6

how can the half life of different isotopes vary?

Answer 6

less than a second to millions of years.

Question 7

what are the characteristics of isotopes with a short half life?

Answer 7

very unstable and emit radiation very quickly so exposure can be very hazardous.
do not remain radioactive for very long.

Question 8

what are the characteristics of an isotope with a long half life?

Answer 8

more stable and remain radioactive for a very long time.
emit radiation slowly so exposure is less hazardous.