CBSE Class 11th Introduction to Structure of Atom

At the most fundamental level, everything in our environment is made of atoms. In actuality, every living thing is made out of atoms. Every non-living object in our environment, including tables, chairs, water, etc., is made of matter. But atoms are the fundamental units of matter. Atoms therefore make up everything, living or non-living. Let's examine atoms and their structures.

Atoms

The word "atom" is Greek for "indivisible." The Greeks held that substances could be divided into atoms, which are minuscule, invisible particles. John Dalton and other Greek thinkers, like Democritus, introduced the idea of the atom.

• The nature of matter was explained by Democritus. He suggested that all substances are composed of matter. In addition, he said that atoms move all the time. These are microscopic, invisible particles that vary in size, shape, and temperature. and that atoms cannot be destroyed.

• John Dalton put forth the atomic idea later in 1808. He gave an explanation of the chemical combination law. Many scientists have created and put forth a number of theories on the "atom.". Specifically, J.J. Thomson, Bohr, Rutherford, and Goldstein, among others.

• The smallest unit of matter is an atom. It is made up of a positively charged core known as the "nucleus." Moreover, the core nucleus is surrounded by negatively charged electrons. Despite being the smallest unit of matter, an atom still retains all of an element's chemical characteristics. For instance, a silver spoon is composed of silver atoms together with a few other elements. A silver atom's characteristics are determined by the minute subatomic particles that make up the atom.

• Molecules are bigger structures made up of additional arrangements and organization of atoms. Even when they are components of a living human body, atoms and molecules follow the general laws of physics and chemistry. To learn more about how atoms behave, respond, and interact, let's now examine their structure.

Structure of Atom

The structure of atom consists of two parts:

• an atomic nucleus
• extra nucleus part

An atom's center is its small atomic nucleus. It is made up of uncharged particles called "neutrons" and positively charged particles called "protons." Conversely, the area containing the additional nucleus is significantly larger. It is made up of one electron, which is a cloud of negatively charged particles. The nucleus is the center of an orbit for electrons. The attraction between protons and electrons maintains the integrity of the atomic structure.
These three subatomic particles make up the majority of all atoms, with the exception of hydrogen. Among all the atoms, hydrogen is unique in that it only has one proton, one electron, and no neutrons. The kind of element an atom has is determined by its proton count. On the other hand, an atom's electron count indicates the kinds of processes that will occur within it.
In an atom's structure, the atomic nucleus is made up of a set number of protons. Additionally, an atom becomes electrically neutral because the proton draws in an equal number of electrons. Ions are created when electrons are added to or taken away from an atom.

Discovery of an Electron:

A British physicist by the name of J.J. Thompson first suggested the theory that an atom is made up of at least one negatively charged particle in 1897. Initially called "corpuscles," it was subsequently dubbed "electron."
The letter "e" stands for an electron, which adds to an atom's negative charge. A negative charge of 1.6×10-19 coulombs is the absolute charge of an electron. An electron has a relative mass of 1/1836. Moreover, an electron has no mass.

Discovery of Proton:

Rutherford made the discovery of protons during the well-known gold foil experiment. Goldstein used a perforated cathode to experiment with a discharged tube and found the presence of positively charged rays in 1886. The beams were referred to as canal or anode rays. Protons were discovered through a series of tests. The particles that give an atom its positive charge are called protons.
"p" stands for proton. A proton's positive charge, measured in 1.6×10-19 coulombs, represents its absolute charge. A proton's mass is 1.6×10^-24 g, which is equivalent to one hydrogen atom's mass.

            
Discovery of Neutron:

The year 1932 marked the discovery of the neutron. The neutron was discovered by James Chadwick. He determined the mass of the neutral particle using scattered particles. The nucleus of an atom contains the subatomic particle known as a "neutron."n" stands for neutron. It's an unbiased particle. A neutron has a mass of 1.6 x 10^-24 g.The gram is not a suitable unit of measurement for these minuscule subatomic particles. However, the atomic mass unit, or dalton, is more appropriate. Moreover, the masses of protons and neutrons are almost equal to one amu.

FAQ: 

Q. What is the structure of an atom?

Ans. An atom consists of a central nucleus composed of protons and neutrons, surrounded by a cloud of electrons in various energy levels or orbitals.

Q. What are the three main subatomic particles and their roles in the atom?

Ans. Protons and neutrons are located in the nucleus, with protons carrying a positive charge and neutrons having no charge. Electrons orbit the nucleus and carry a negative charge.

Q. How do electrons, protons, and neutrons contribute to the overall structure of an atom?

Ans. Electrons determine the chemical properties of an atom by participating in chemical reactions. Protons and neutrons contribute to the atom's mass and stability.

Q. What is the Bohr model of the atom, and how does it explain atomic structure?

Ans. The Bohr model proposes that electrons orbit the nucleus at specific energy levels, or shells. It explains atomic emission spectra and the stability of certain electron configurations.

Q. What is electron configuration, and how does it relate to the structure of atoms?

Ans. Electron configuration describes the arrangement of electrons in an atom's orbitals. It helps predict an atom's chemical behavior and its position in the periodic table.

Q. How are the number of protons and electrons related in an atom?

Ans. In a neutral atom, the number of protons (positive charge) equals the number of electrons (negative charge), balancing each other out.

Q. What is the significance of the atomic nucleus in the structure of an atom?

Ans. The nucleus contains most of the atom's mass and determines its identity. It also governs nuclear reactions and radioactive decay.

Q. How does the concept of orbitals contribute to our understanding of atomic structure?

Ans. Orbitals describe regions around the nucleus where electrons are likely to be found. They help visualize electron distribution and predict chemical behavior.

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