## The World of Atom (Part III)

Reference: Boorse 1966: The World of Atom

## Chapter 14: Atoms in Motion (John Herapath 1790 – 1868)

According to Herapath the relationship among temperature, pressure, and density applied to the supposed aethereal medium also. He basically came up with the kinetic theory of gases on his own. His particles moved by an intrinsic motion with perfect freedom. Herapath substituted Newton’s repulsive forces among the particles of gases by their intrinsic motion. He theorized that gas heats up on sudden compression and cools down on sudden expansion because of change in velocity of the particles.

## Chapter 15: “Active Molecules” – Brownian Motion (Robert Brown 1773 – 1858)

Brownian motion is an effect arising from the imbalance of molecular impacts on a free microscopic particle. In this sense, molecules have a primitive form of life as they have self-propelled motion. An inherent motion of the molecules underlies the Kinetic theory of gases.

## Chapter 16: The Tragedy of a Genius (John James Waterston 1811 – 1883)

Waterston was the first to introduce the conception that heat and temperature are to be measured by vis viva (kinetic energy). He showed that under equal pressure and volume, the root mean square velocity is inversely proportional to mass density. Waterston, thus, not only corrected the relationship of temperature to velocity but also gave the first statement of the law of equipartition of energy in a mixture at thermal equilibrium.

## Chapter 17: The Conservation of Energy–The Mechanical Equivalent of Heat (James Prescott Joule 1818 – 1889)

Joule firmly established the idea that mechanical energy could be transformed into internal energy and thus produce the same effect as “heating” a body, and that a fixed ratio existed between mechanical work and thermal units. Heat is properly defined as energy in transit due solely to a temperature difference.  Joule saw that chemical energy in battery is converted to electrical energy in the circuit and that this in turn is converted into heat. This ultimately established the Law of Conservation of Energy.

## Chapter 18: The Range of Molecular Speeds in a Gas (James Clerk Maxwell 1831 – 1879)

Maxwell brilliantly deduced the distribution of molecular speeds in a gas at equilibrium at any temperature. This great step forward in the understanding of the behavior of the elementary particles of gases represents one of the major advances in the progress of the atomic theory of matter. Besides, Maxwell provided a formula for the coefficient of viscosity of a gas which showed this quantity to be independent of pressure, a most unexpected and surprising result.

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MAIN POINTS

1. Atoms and molecules move by an intrinsic motion with perfect freedom.
2. The root mean square velocity is inversely proportional to mass density under equal pressure and volume.
3. The molecular speeds in a gas at any temperature has a certain distribution.
4. The imbalance of molecular impacts on a free microscopic particle makes it move randomly.
5. Particles have kinetic energy that depends on their velocity.
6. Temperature depends upon the velocity of such particles.
7. Heat and temperature are to be measured by kinetic energy.
8. Heat is energy in transit due solely to a temperature difference.
9. Kinetic heat energy of a gas is equally divided between linear and rotational energy.
10. Fixed ratio exists between mechanical work and thermal units produced.
11. Energy takes different forms but the total energy is conserved.

THEORY
The atomic and molecular particles have intrinsic motion. This is expressed as inherent kinetic energy. This energy manifests as momentum, heat, chemical activity, and electrical force. It gives rise to the properties of pressure, temperature, volume  and density of gases. The total momentum and energy are conserved.

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