2.9. Atomic Structure: Periodic Table

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The atomic structure and the periodic table are two integral parts of the study of chemistry, especially when it comes to preparing for the ENEM test. Understanding these concepts is critical to solving questions related to chemistry on the test.

Atomic Structure

An atom is the smallest unit of a substance that retains all the chemical properties of that substance. Atomic structure refers to the arrangement of protons, neutrons, and electrons that make up a single atom.

The protons and neutrons are located in the nucleus of the atom, while the electrons orbit the nucleus in paths known as orbitals. Protons have a positive charge, neutrons have no charge, and electrons have a negative charge. The number of protons in an atom is known as the atomic number and determines the element to which the atom belongs in the periodic table.

Electrons occupy different energy levels around the nucleus, known as electron shells. The distribution of these electrons is crucial to understanding how atoms interact with each other to form chemical compounds.

Periodic Table

The periodic table is a visual representation of chemical elements organized based on their atomic properties. Dmitri Mendeleev is credited with creating the first version of the modern periodic table. He arranged the elements in order of increasing atomic number, a strategy that revealed a periodicity in the properties of elements.

The modern periodic table is organized into seven periods (horizontal lines) and 18 groups (vertical columns). Elements in a group have the same number of electrons in the valence shell, which is the outermost shell of electrons. This results in elements from the same group having similar chemical properties.

Elements in the periodic table are also categorized as metals, non-metals, or metalloids. Metals are found on the left and center of the table, while non-metals are on the right. Metalloids, which have properties of both metals and non-metals, form a diagonal line between metals and non-metals.

Understanding the periodic table and atomic structure is crucial to the study of chemistry. These concepts form the basis for understanding how atoms interact to form compounds and how chemical reactions occur. Furthermore, they are frequently tested on the ENEM exam, making their understanding even more vital for students.

In our e-book course, we will go deeper into these concepts, providing detailed explanations, practical examples and practice questions to help you prepare for the ENEM exam. With a strong understanding of atomic structure and the periodic table, you will be well prepared to tackle any chemistry question that may come up on the exam.

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122.10. Atomic Structure: Periodic Properties