High School Chemistry : Help with Radioactive Decay
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Example Question #11 : Help With Radioactive Decay
A radioactive isotope has an exponential decay as pictured in the above plot of sample amount vs time. From the graph, estimate the half-life of the isotope.
15 days
2.5 days
5 days
10 days
5 days
To estimate the half-life we just see how long it takes for the sample to be cut in half. The green lines indicate when there is half the initial sample (
Check: Will the sample be cut in half again after another 
Example Question #11 : Help With Radioactive Decay
What is the relationship between neutrons and protons of nuclides with respect to zone of stability?
As the number of protons decreases, the number of neutrons increases.
As the number of protons decreases, the number of neutrons decreases.
As the number of protons increases, the number of neutrons increases.
As the number of protons increase, the number of neutrons decreases.
As the number of protons increases, the number of neutrons stagnates.
As the number of protons increases, the number of neutrons increases.
First of all, it's important to understand terminology used in this kind of a concept question. A nuclide refers to a particular atom or nucleus with neutrons and protons. As we know, neutrons refer to the neutrally charged particles within a nucleus, while protons refer to those that are positively charged.
The zone of stability is a roughly linear pattern that follows a positive correlation with number of protons and neutrons. As the number of protons increases in the nucleus, so does the number of neutrons to allow for stability.
When a nuclide falls above or below the zone of stability, it creates a beta or alpha positron, respectively. These nuclides would not be considered stable, as they show degradation over time.
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