2.20. Atomic Structure: Half-life

Atomic structure is one of the main concepts in chemistry and is essential for understanding many other topics in science. In this chapter of our e-book, we are going to explore a specific aspect of atomic structure - the half-life.

Half-life is the time required for half of the atoms in a sample of a radioactive isotope to decay. This is important because radioactivity is a random process, but the half-life of an isotope is constant. This means that we can use half-life to predict how much of a radioactive isotope will still be present after a certain period of time.

Let's start with the basics. An atom is composed of a nucleus of protons and neutrons, surrounded by a cloud of electrons. Isotopes are atoms of the same element that have different numbers of neutrons. Some isotopes are stable, meaning their nuclei don't change over time. Other isotopes are unstable or radioactive, meaning their nuclei decay over time, releasing radiation.

The rate of decay of a radioactive isotope is measured in terms of its half-life. For example, if an isotope has a half-life of 5 years, that means that after 5 years, half of the atoms in the sample will have decayed. After another 5 years, half of the remaining atoms will have decayed, and so on.

Half-life is an intrinsic property of each radioactive isotope and is not affected by external factors such as temperature or pressure. This makes it a useful tool for a variety of applications, from dating fossils to determining the age of a star.

Understanding half-life is also crucial for safe handling of radioactive materials. For example, nuclear waste from a nuclear power plant can remain radioactive for thousands of years. Therefore, it is important to know how long these materials will continue to be a potential source of radiation.

So how can we calculate the half-life of an isotope? The basic formula is:

Half-life = 0.693 / (Rate of disintegration)

The rate of disintegration is the number of atoms that disintegrate per unit of time. Therefore, if we know the decay rate of an isotope, we can calculate its half-life.

In summary, half-life is a fundamental property of radioactive isotopes and is a key concept in understanding radioactivity and atomic structure. Understanding half-life allows us to make predictions about the behavior of radioactive isotopes over time, which has a wide range of applications in science and engineering.

We hope this chapter has given you a solid understanding of half-life and how it relates to atomic structure. In the next chapter, we'll explore more aspects of chemistry that are essential for success on the ENEM exam.

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23Atomic Structure: Radioactive Decay

3 minutes