NEET UG » NEET UG Study Material » Chemistry » Key Notes On Atomic Theory

Key Notes On Atomic Theory

Atoms are indivisible. Specific elements have only one type of atom in them. Each atom has its own constant mass that varies from element to element. Atoms undergo rearrangement during a chemical reaction.

Atomic structure refers to the physical structure of an atom, which is made up of a nucleus (the centre) and protons (positively charged) and neutrons (neutral). The electrons, which are negatively charged particles, surround the nucleus’s attraction centre.

Democritus was the first to suggest that matter is made up of atoms in his theory of matter, and the history of atomic structure and quantum mechanics may be traced back to him. By analysing the structure of the atom, it is possible to get useful insight into the entire class of chemical processes, bonds, and physical properties. The first scientific idea of atomic structure was proposed by John Dalton in the 1800s, and it was accepted by the scientific world.

The Definition of Atomic Structure

When we talk about an element’s atomic structure, we’re talking about the nucleus’ composition as well as the electron arrangement around it. The building components of matter are protons, electrons, and neutrons, which make up the atomic structure of matter.

It is made up of protons and neutrons that make up the atom’s nucleus, which is surrounded by electrons that are also part of the atom. The atomic number of an element represents the total number of protons in its nucleus.

The number of protons and electrons in neutral atoms is the same as the number of electrons. Atoms, on the other hand, can gain or lose electrons to improve their stability, and the resulting charged substance is called an ion in this context.

The atomic structures of different elements differ due to the variable quantities of protons and electrons in each element. Individual elements have various characteristics as a result of this.

Models of Atoms

During the 18th and 19th centuries, a large number of scientists attempted to describe the structure of the atom using atomic models as a starting point. Each of these models had its own set of advantages and disadvantages, and they all played a role in the creation of the present atomic model. A number of renowned scientists, including John Dalton, James J. Thomson, Ernest Rutherford, and Niels B. Bohr, have made significant contributions to the area. These authors’ theories about the structure of the atom are examined in greater detail in the following section.

The Atomic Theory of Dalton

All substance, according to British chemist John Dalton, is made up of atoms, which are considered to be indestructible, indivisible, and unbreakable. According to him, the same element has exactly the same number of atoms, but the atoms of various elements differ in size and mass.

According to Dalton’s atomic theory, chemical reactions are characterised by the rearrangement of atoms that results in the formation of products. In accordance with the postulates established by Dalton, the atomic structure was made up of atoms, which were the smallest particles responsible for the occurrence of chemical reactions.

Dalton’s Theoretical Framework Is Based on The Following Postulates

  • Atoms are the fundamental constituents of all substances
  • Atoms are indestructible and undivided
  • Only one type of atom exists in each element, and it is unique to it
  • Each atom has a fixed mass that varies per element but remains constant for all
  • During a chemical reaction, the atoms’ arrangement changes
  • Atoms cannot be created or destroyed, but they can be transformed from one state to another using the transformation process

Dalton’s Atomic Theory Has a Number of Flaws

  • The existence of isotopes could not be explained by the theory
  • There was no appropriate explanation for the structure of the atom
  • Scientists later identified particles within the atom, demonstrating that atoms may be separated

Atomism

Fundamental indivisible components known as atoms, according to atomism, are the building blocks of the physical cosmos, according to a natural philosophy.

At least two intellectual traditions, ancient Greek and ancient Indian, made reference to the concept of atomism and the atoms that make up its constituent parts. The ancient Greek atomists argued that nature is made up of two fundamental principles: the atom and the void (or nothingness). Clusters of varied shapes, configurations, and placements are responsible for the formation of the numerous macroscopic substances found throughout the universe.

The particles of chemical matter for which chemists and other natural philosophers of the early nineteenth century discovered experimental evidence were thought to be indivisible, and as a result, John Dalton gave them the name “atom,” which has been used ever since by the atomist philosophy of the nineteenth century. Despite the fact that the connection between elementary particles and historical atomism is at best shaky, elementary particles have emerged as a modern equivalent of philosophical atoms.

Atomic Physics Is the Study Of Atoms

Atomic physics is the scientific study of the structure of the atom, its energy levels, and its interactions with other particles as well as with electric and magnetic fields, according to the American Physical Society. It has proven to be an extraordinarily successful application of quantum mechanics, which is considered one of the foundations of modern physics. Atomic physics is one of the most successful applications of quantum mechanics to date.

Conclusion

Thomson described the atomic structure as a positively charged sphere with negatively charged electrons buried within it based on his cathode ray experiments.

It’s known as the “plum pudding model” because it can be visualised as a plum pudding plate with the pudding representing the positively charged atom and the plum pieces representing the electrons.

Atoms are electrically neutral, according to Thomson’s atomic structure, which means that the positive and negative charges on an atom have equal magnitudes.

faq

Frequently asked questions

Get answers to the most common queries related to the NEET UG Examination Preparation.

What are subatomic particles, exactly, and what are their functions?

Answer. Subatomic particles are the particles that make up an atom. In general, this term refers to protons, electro...Read full

How do isotopes' atomic structures differ?

Answer. They differ in terms of the total amount of neutrons in the atom’s nucleus, as shown by their nucleon ...Read full

What are some of the flaws in Bohr's atomic model?

Answer. The structure of an atom, according to this atomic model, provides poor spectrum predictions for larger atom...Read full

How can the total number of neutrons in an isotope's nucleus be determined?

Answer. The total number of protons and neutrons in an isotope is used to calculate its mass number. The total numbe...Read full

What are the atomic theory's main concepts?

Answer. All matter is made up of indivisible atoms, according to the first component of his theory. The theory’...Read full