2.18. Atomic Structure: Isotones

To understand the concept of isotones, we must first revisit basic atomic structure. The atom is the basic unit of matter, composed of three subatomic particles: protons, neutrons and electrons. Protons and neutrons are located in the nucleus of the atom, while electrons orbit around the nucleus in regions called electron shells.

Protons are positively charged, electrons are negatively charged, and neutrons are neutral particles. The number of protons in an atom is known as the atomic number and is unique to each element in the periodic table. The mass number of an atom is the sum of the number of protons and neutrons in the nucleus of the atom.

Using this basis, we can define isotones. Isotones are atoms that have the same number of neutrons but different atomic numbers. For example, the isotopes of hydrogen (protium, deuterium and tritium) have 0, 1 and 2 neutrons respectively, but all have 1 proton. Therefore, they are isotone to each other.

Isotones are important in both chemistry and physics. In nuclear physics, isotones are used to study the structure of the atomic nucleus and radioactive decay processes. In chemistry, isotones are used to track chemical reactions and understand reaction mechanisms.

Isotones also have practical applications. For example, the isotone uranium-235 is used as a fuel in nuclear reactors and in nuclear weapons. Likewise, the carbon-14 isotone is used in radiocarbon dating to determine the age of ancient artifacts and fossils.

It is important to note that although isotones have the same number of neutrons, they can have very different chemical properties. This is because the chemical properties of an element are determined by the number of electrons in its outermost shell, known as the valence shell, rather than the number of neutrons in the nucleus.

Therefore, when studying chemistry for ENEM, it is important to understand the distinction between isotones, isobars (atoms with the same mass number but different atomic numbers) and isotopes (atoms of the same element with different numbers of neutrons). Each of these concepts provides a different view of atomic structure and has its own applications and implications.

In summary, atomic structure and the concept of isotones are fundamental to understanding chemistry. They are the foundation for understanding how atoms interact with each other to form molecules and compounds, and how these interactions determine the properties and behaviors of substances. Therefore, a good understanding of these concepts is essential for success in the ENEM and other chemistry exams.

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