Atomic Theory is a scientific concept that explains the nature of matter and its behavior. It is the foundation of modern physics and chemistry.
Over the years, several models have been proposed to explain the structure of atoms and their behavior. Today, the accepted model of Atomic Theory is the Quantum Mechanical Model.
The Early Models
The earliest model of Atomic Theory was proposed by John Dalton in the early 19th century. He suggested that atoms were indivisible and indestructible particles that could combine to form compounds. However, this model was later disproved by J.J Thomson’s discovery of the electron in 1897.
Thomson’s “plum pudding” model proposed that atoms were made up of a positively charged substance with negatively charged electrons embedded within it. This model was further refined by Ernest Rutherford’s gold foil experiment in which he discovered the positively charged nucleus at the center of an atom.
The Quantum Mechanical Model
The Quantum Mechanical Model, also known as the Wave Mechanical Model, is today’s accepted model of Atomic Theory. It was developed in the 1920s by Erwin Schrödinger, Werner Heisenberg, and others.
This model suggests that electrons do not orbit around a nucleus as previously believed but instead exist in an electron cloud around it. The cloud represents all possible locations where an electron may be found at any given time.
The behavior of electrons can be described using mathematical equations known as wave functions or orbitals. These equations predict both the probability distribution and energy levels of electrons within an atom.
The Quantum Mechanical Model also recognizes three subatomic particles within an atom: protons, neutrons, and electrons.
Protons are positively charged particles found in the nucleus while neutrons are neutral particles also found in the nucleus. Electrons are negatively charged particles found outside the nucleus in the electron cloud.
The Periodic Table
The Quantum Mechanical Model has also led to a better understanding of the periodic table. The rows, or periods, of the periodic table are based on the number of electron shells in an atom while the columns, or groups, are based on the number of valence electrons.
In conclusion, the Quantum Mechanical Model is today’s accepted model of Atomic Theory. It has provided a better understanding of matter and its behavior, including subatomic particles and the periodic table. By understanding Atomic Theory, we can gain insight into many areas of science and technology.