Radioactive Decay + Nuclear Energy

The decay of single atoms are random however as a whole, a pattern does appear. This is similar to a bubble bath: it’s impossible to predict which bubble will pop but you can start to see a pattern of decay over time.

The half-life is the time it takes for half an atom to decay.

Different isotopes have different half-lives! Look below to see an example of this:



Final Amount = Initial Amount * (1/2) time/half-life


AF = AI * (1/2) t/h

Furthermore, an experiment was conducted in class where a total of 49 skittles were provided at the start. A container with the total non-decayed skittles was shaken for a duration (this duration started at 5 seconds, and increased by 5 seconds every round). After the skittles were “randomized” the ones with the letter S facing upwards were considered decayed and thus were discarded. This was repeated until all the skittles were “decayed”. The skittles represented radioactive nuclei.

The graph and table below represent the findings of this lab. The graph clearly shows an exponential decay (when looking at the curve of best fit):


As can be seen in the table, it was impossible to predict exactly how many skittles would decay each round but it is possible to predict the pattern (exponential decay).

Nuclear Reactions:

A process in which atoms collide with other atoms. As a result, they lose some of their original mass. However, where did the mass go? Well this mass reappears as generated energy (which Einstein’s E = mc2 shows).


A typical fission reaction consists of an atom of uranium 235 that absorbs a neutron and splits into 2 lighter atoms. It also emits radiation and neutrons. However, the neutrons can then split more atoms (followed by of course, more splitting) which results in a fast chain reaction. Nuclear power plants use this method to create energy.


A typical fusion reaction consists of 2 light atomic nuclei that fuse to form a heavier nucleus. The mass change is what sources this method’s energy. In the sun, it’s 2 hydrogen atoms that fuse to create a helium atom.


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