Atomic Structure Basics

Atomic Structure

• An atom consists of a nucleus (centre) containing protons (positively charged) and neutrons (neutral), surrounded by negatively charged electrons.
• The study of atomic structure provides insight into chemical reactions, bonds, and physical properties.

History of Atomic Structure

• Democritus first proposed that matter is composed of atoms.
• John Dalton proposed the first scientific theory of atomic structure in the 1800s.

Subatomic Particles

• The discovery of subatomic particles has led to many other discoveries and inventions.
• The atomic structure of an element is made up of protons, electrons, and neutrons.

Atomic Number and Ions

• The atomic number of an element describes the total number of protons in its nucleus.
• Neutral atoms have equal numbers of protons and electrons.
• Atoms may gain or lose electrons to form ions, increasing their stability.

Atomic Models

• Many scientists, including John Dalton, J.J. Thomson, Ernest Rutherford, and Niels Bohr, have contributed to the development of atomic models.
• Each model has its own merits and demerits.

Dalton's Atomic Theory

• John Dalton suggested that all matter is made up of atoms, which are indivisible and indestructible.
• Atoms of different elements differ in size and mass.
• Dalton's atomic theory explained the Laws of chemical reactions, including the Law of conservation of mass and the Law of constant properties.

Demerits of Dalton's Atomic Theory

• The discovery of particles inside atoms led to a better understanding of chemical species.

Thomson Atomic Model

• J.J. Thomson proposed a model describing the atomic structure in the early 1900s.
• His work is based on the cathode ray experiment, which led to the discovery of "electrons".

Learn about the fundamental structure of atoms, including the nucleus and subatomic particles, and how it relates to chemical reactions and physical properties. Explore the history of atomic structure theories.