Use the following decay curve for iodine-131 to answer problems a to c: (5.4) b. Complete the number of days on the horizontal axis.

Verified step by step guidance

1. Identify the half-life of iodine-131 from the graph by observing the time it takes for the amount of substance to reduce to half its initial value.
2. Note the initial amount of iodine-131 at day 0, which is 200 mg, and find the point where it reduces to 100 mg to determine the half-life.
3. Observe the graph to see that the amount reduces to 100 mg at approximately 8 days, indicating the half-life of iodine-131 is 8 days.
4. Use the half-life to calculate the number of days for subsequent reductions in the amount of iodine-131, such as when it reduces to 50 mg, 25 mg, etc.
5. Complete the horizontal axis by marking the days at which each half-life occurs, using the pattern observed from the graph.

Key Concepts

Radioactive Decay

Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation. This decay occurs at a predictable rate, characterized by the half-life, which is the time required for half of the radioactive substance to decay. Understanding this concept is crucial for interpreting decay curves, as they visually represent the decrease in quantity of a radioactive isotope over time.

Half-Life

Half-life is a specific measure of time that indicates how long it takes for half of a given quantity of a radioactive substance to decay. For iodine-131, the half-life is approximately 8 days. This concept is essential for calculating the remaining amount of a substance at any given time and is fundamental in fields such as nuclear medicine and radiometric dating.

Decay Curve

A decay curve is a graphical representation that shows the decrease in quantity of a radioactive substance over time. The x-axis typically represents time (in days, for example), while the y-axis shows the remaining amount of the substance. Analyzing the decay curve allows one to determine the rate of decay and predict the amount of substance remaining at specific intervals, which is vital for solving problems related to radioactive materials.