Readings

2/7/12

Today we will learn about how our dice-rolling activity is connected to the decay of radioactive substances. Read the following paragraph about radioactive decay, using the hyperlinks to explore new or confusing terms (there are some big words) and answer the questions below.


 * Radioactive decay ** is the process by which an [|atomic nucleus] of an unstable atom loses energy by emitting ionizing particles ( [|ionizing radiation] ). The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom. Usually, radioactive decay happens due to a process confined to the nucleus of the unstable atom, but, on occasion (as with the different processes of [|electron capture] and [|internal conversion] ), an inner electron of the radioactive atom is also necessary to the process.

Radioactive decay is a [|stochastic] (i.e., random) process at the level of single atoms, in that, according to [|quantum theory], it is impossible to predict when a given atom will decay. However, the chance that a given atom will decay is constant over time. For a large number of identical atoms (of the same [|nuclide] ), the decay rate for the collection is predictable to the extent allowed by the [|law of large numbers], and is easily calculated from the measured [|decay constant] of the nuclide (or equivalently from the [|half-life] ) (Wikipedia).

1. In radioactive decay, what is playing the role of “dice?”

2. What sentence shows that radioactive decay is similar in a fundamental way to our dice rolling?

3. What two-word term refers to the idea that on average we removed about 17% of the dice on each roll?

4. What does “half-life” mean?

5. Why is the “Law of Large Numbers” used when talking about radioactive decay?