Introduction to the Atom

Relevance of the Topic

Studying the atom is one of the cornerstones of modern Chemistry and Physics, with direct applications in various fields of knowledge, including Engineering, Medicine, Geology, and Astronomy. Understanding the structure and characteristics of the atom is essential to comprehend how matter is formed and how different substances interact with each other, leading to a multitude of phenomena and chemical reactions.

Contextualization

The atom is the fundamental unit of matter. It is so small and basic that for a long time, scientists believed it was the smallest existing particle. However, with the advancement of technology and the improvement of research instruments, we discovered that the atom is composed of even smaller particles, such as protons, neutrons, and electrons. These particles have specific characteristics and properties that determine the behavior of matter. Therefore, by studying the atom, we delve into the deepest structure of the material universe.

The study of the atom is directly linked to Atomic Theory, which is an essential part of the basic Science curriculum. Understanding the atom provides us with the necessary tools to comprehend concepts such as mass, density, chemical reactivity, energy, and many other important topics. Furthermore, the atom is an active and constantly evolving field of study, with new discoveries being made regularly. Therefore, this is a topic that deserves attention, as it will not only provide a solid foundation for the study of sciences but also a fascinating insight into the world around us and beyond.

Theoretical Development

Components of the Atom:

• Protons: Particles found in the nucleus of the atom, with a positive electric charge. The number of protons defines the chemical element. For example, hydrogen has 1 proton, helium has 2, carbon has 6, and so on.

• Neutrons: Also located in the atom's nucleus, neutrons have no electric charge, giving the atom its mass. The number of neutrons can vary for the same chemical element, forming isotopes.

• Electrons: Found in orbit around the nucleus, electrons have a negative electric charge, which is balanced by the positive charge of protons. The number of electrons is equal to the number of protons in a neutral atom.

Atom Characteristics:

• Atomic Number (Z): It is the number of protons in an atom, defining the chemical element. In the periodic table, elements are arranged in increasing order of atomic number.

• Mass Number (A): It is the sum of the number of protons and the number of neutrons. Generally, various forms of the same element have different mass numbers, these are isotopes.

• Electron Energies: Electrons can occupy different energy levels around the nucleus. The energy levels are represented by layers, with the first one being the closest to the nucleus. The distribution of these electrons follows the Octet Rule, which determines that atoms tend to gain, lose, or share electrons so that their outermost layer has 8 electrons, equal to the configuration of the nearest noble gas in the periodic table.

Key Terms:

• Atomic Theory: It is a theory that describes the fundamental nature of matter and how it behaves. It was first proposed in Ancient Greece and has since undergone many revisions and updates.

• Isotopes: Isotopes are atoms of the same chemical element, meaning they have the same number of protons but a different number of neutrons. Thus, the mass number (A) is different.

• Electronic Configuration: It is the arrangement of electrons in an atom. It determines many of an atom's properties, including its chemical behavior.

Detailed Summary

Relevant Points:

• Atom: It is the fundamental unit of matter, composed of protons and neutrons in the nucleus, and electrons orbiting around the nucleus. Its study allows the understanding of substance formation and interaction.

• Protons: Particles with a positive electric charge located in the atom's nucleus. The number of protons determines the chemical element.

• Neutrons: Particles without an electric charge located in the atom's nucleus. The number of neutrons can vary for the same element, forming isotopes.

• Electrons: Particles with a negative electric charge that orbit around the atom's nucleus. The number of electrons is equal to the number of protons in a neutral atom.

• Atomic Number (Z): Represents the number of protons in an atom and is responsible for defining the chemical element in the periodic table.

• Mass Number (A): Sum of the number of protons and neutrons in an atom. Various forms of the same element can have different mass numbers (isotopes).

• Atomic Theory: It is the theory that describes the nature of matter and its structure. It has evolved over time with advances in science.

• Isotopes and Electronic Configuration: Isotopes have the same number of protons but different numbers of neutrons. Electronic configuration is how electrons are arranged around the nucleus and influences chemical properties.

Conclusions:

• The atom's structure is composed of protons, neutrons, and electrons. Protons and neutrons form a nucleus at the center of the atom, while electrons orbit around this nucleus.

• The electric charge of protons is positive, that of electrons is negative, and neutrons have no charge. The atom is electrically neutral when the quantity of protons is equal to that of electrons.

• Theoretically, electrons can occupy infinite energy levels around the nucleus. However, they tend to occupy the lowest available energy levels, following the Octet Rule.

• The concept of isotopes is important because atoms of the same chemical element can have different masses due to variations in the number of neutrons.

Solved Exercises:

1. Exercise 1: The hydrogen atom has one proton and one electron. If the electron's charge is -1, what is the total charge of the hydrogen atom?

Solution: The total charge of the atom is the sum of the charges of the protons and electrons. Since the proton has a charge of +1 and the electron -1, we have +1 + (-1) = 0. Therefore, the hydrogen atom is electrically neutral.

2. Exercise 2: The most common isotope of carbon is carbon-12, which has 6 protons and 6 neutrons. How many electrons does this isotope have?

Solution: The number of electrons in a neutral atom (without charge) is equal to the number of protons. Therefore, the carbon-12 isotope has 6 electrons.

3. Exercise 3: What is the atomic number of an element that has 26 electrons and 26 neutrons?

Solution: The atomic number is equal to the number of protons. If the element has 26 electrons, which is equal to the number of protons in a neutral atom, then the atomic number is 26.