The World of Atom (Part VII)



Chapter 37: The “Thomson” Atom (J. J. Thomson 1856 – 1940)

[From Wikipedia] The plum pudding model is one of several historical scientific models of the atom. First proposed by J. J. Thomson in 1904 soon after the discovery of the electron, but before the discovery of the atomic nucleus, the model tried to explain two properties of atoms then known: that electrons are negatively charged particles and that atoms have no net electric charge. The plum pudding model has electrons surrounded by a volume of positive charge, like negatively charged “plums” embedded in a positively charged “pudding”.

From the very beginning we have associated electrons with unit charges and point configurations within the atom. This gives the impression that electrons are particles, but we know that they do not have point mass. They simply have thick consistency and distributed inertia. The quantum numbers associated with electrons come from their whirlpool-like motion in the atom. The charge exists at the interface between the mass of the nucleus and the distributed inertia of surrounding electrons. The charge does not neutralize because it is part of a stable whirlpool-like configuration. Any attraction or repulsion exists because charges want to re-establish that whirlpool-like configuration.

Chapter 38: The Determination of Avogadro’s Number (Jean Perrin 1870 – 1942)

The Avogadro constant is the proportionality factor that relates the number of constituent particles (usually molecules, atoms or ions) in a sample with the amount of substance in that sample. The numeric value of the Avogadro constant expressed in reciprocal mole, a dimensionless number, is called the Avogadro number, sometimes denoted N or N0, which is thus the number of particles that are contained in one mole, exactly 6.02214076×1023.

The experimental setup works because there is incessant motion of the molecules that generates Brownian motion. This motion in the solution helps maintain a certain distribution of suspended particles according to their height. The incessant motion arises because of the difference in consistencies of the nucleus and the electrons. 

Chapter 39: The α-Particle and Helium (Ernest Rutherford 1871 – 1937)

Radioactivity of Uranium was discovered in 1896 by Henri Becquerel. In 1899, Ernest Rutherford discovered α and β rays from radioactive emissions. In 1900, Paul Villard discovered γ rays as a natural emission from radium. α rays were defined by Rutherford as those having the lowest penetration of ordinary objects. Rutherford’s work also included measurements of the ratio of an alpha particle’s mass to its charge, which led him to the hypothesis that alpha particles were doubly charged helium ions. In 1907, Ernest Rutherford and his student, Thomas Royds, finally proved using a simple and elegant experiment that alpha particles were indeed helium ions.

Alpha rays, indeed, consist of mass particles. They are bare helium nuclei; so they are called particles correctly.

Chapter 40: Atoms of Electricity (Robert Andrews Millikan 1868 – 1953)

Thomson’s experiments in 1897 measured the ratio of charge to mass, e/m, of the cathode ray particles. The necessity of determining the value of e was immediately clear to Thomson. In 1909, Millikan showed unambiguously that nature supplies electric charge only in one fixed size, that all charges, no matter where they may occur, are only multiples of this charge, and that electric charges of any other magnitude do not exist.

The unit charge is part of the atomic configuration. It does not exist outside this configuration. It is the minimum amount of charge that appears in an atomic interaction. Therefore, it relates to the consistency of the cathode rays.



  1. The number of particles that are contained in one mole, is exactly 6.02214076×1023.
  2. The atom as a whole is neutral, so it must have positive charge too.
  3. There are negative and positive ions.
  4. The unit charge appears on ions and does not exist otherwise.
  5. The charge carried on by an ion in gases is the same as the charge on the beta or cathode-ray particle.
  6. The α-particles with positive charges are indeed ionized helium atoms.
  7. The charge to mass ratio of electron is 2000 times greater than hydrogen ions.
  8. The speed of electron is many thousand times higher than the speed of hydrogen ions.
  9. The number of electrons in an atom is between half and whole of atomic weight units.
  10. The electron arrangements may cause periodic properties of chemical elements.

A neutral atom consists of both positive and negative charges in equal amounts. The charges in atom do not neutralize because they are part of a stable whirlpool-like configuration. A unit charge at the level of atom may be determined just like the unit mass. The electronic charge may be added or removed to produce negative and positive ions respectively.


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