2.19. Atomic Structure: Radioactivity

The atomic structure and radioactivity are central themes in the study of Chemistry and are frequently addressed in the ENEM test. To understand radioactivity, we must first understand atomic structure.

The atom is the smallest particle of an element that retains the properties of that element. It is made up of three types of subatomic particles: protons, neutrons, and electrons. Protons and neutrons are located in the nucleus of the atom, while electrons orbit the nucleus in layers of energy called electron shells.

Protons have a positive charge, neutrons have no charge (they are neutral), and electrons have a negative charge. The number of protons in an atom is what determines the chemical element. For example, all hydrogen atoms have one proton, while all oxygen atoms have eight protons.

Now, let's talk about radioactivity. Radioactivity is a natural phenomenon that occurs when an unstable atom emits particles or energy to become more stable. There are three main types of radiation: alpha, beta, and gamma.

Alpha radiation is made up of alpha particles, which are essentially nuclei of helium atoms. They are made up of two protons and two neutrons. Alpha radiation is the least penetrating of the three, but it can still be dangerous if ingested or inhaled.

Beta radiation is composed of beta particles, which are essentially high-energy electrons. These particles are emitted when a neutron in the nucleus of an atom breaks down into a proton and an electron. Beta radiation is more penetrating than alpha radiation, but less penetrating than gamma radiation.

Gamma radiation is high-energy electromagnetic waves, similar to X-rays. It is the most penetrating of the three and can easily pass through most materials. Gamma radiation is emitted when an atomic nucleus passes from a higher energy state to a lower energy state.

Radioactivity has many practical applications, including generating power in nuclear power plants, treating cancer, and dating archaeological artifacts. However, it can also be dangerous if not handled correctly. Exposure to high levels of radiation can cause illness and even death.

In summary, atomic structure and radioactivity are fundamental concepts in Chemistry that you need to understand in order to do well in the ENEM test. Remember that atomic structure refers to the composition of atoms, including protons, neutrons and electrons, while radioactivity refers to the emission of particles and energy by unstable atoms.

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22Atomic Structure: Half-life

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