John Dalton: Revival of Atomism - Report Example

John Dalton – Revival of Atomism John Dalton was a Chemist, Meteorologist, Physicist, Philosopher and father of the Atomic Theory which is the foundation of the modern day science. It is not that the concept of atoms or the particles which cannot be cut (a – no and tome – to cut) was not there before, in fact the concept can be found in many ancient philosophies, however, it was John Dalton, who gave the scientific basis to such a great concept and therefore, he can is rightly credited as father of the Atomic theory. John Dalton was born on September 6, 1766 in a weaver family at Eaglesfield in Cumbria. After helping his elder brother in running a school for a couple of years he wanted to pursue his studies in either law or medicine. However, this idea of his was not encouraged by his relatives. In 1793, he moved to Manchester. He was mentored by a blind philosopher John Gough in Mathematics, Philosophy and Science. Subsequently, he joined New College in Manchester as a teacher of Mathematics and Philosophy. He was with this college until 1800 and subsequently he left this job and started private tuitions in the same subjects namely Mathematics and Natural Philosophy. He was a member of “Manchester Literary and Philosophical Society” the Lit and Phil since 1794 and by 1800 he became secretary of this Society. He published and presented many papers through this Society and all these papers were of great scientific importance. His very first paper was related to color blindness, of which he himself was a victim and due to his pioneering contributions towards understanding color blindness this disease is named after him “Daltonism”. His great contributions to the field of natural science and philosophy are – Atomic Theory, Law of Multiple Proportions, Dalton’s Law of Partial Pressures and Daltonism – to name a few. On the account of his contribution – mainly the Atomic Theory, he can be termed a one of the father figures of modern science. He died on July 23, 1844. Important Contributions John Dalton made great contributions to the modern day science and natural philosophy. He was a great blend of an experimental scientist and a philosopher. His experiments were mainly in the field of chemical reactions involving gases and the properties of the gases and he synthesized his great theories from his experiments. He was said to be a crude experimentalist and not a sophisticated experimentalist but the fact that he could synthesize such great theories from his crude experiments speaks a lot about his intellect. In subsequent sections we will briefly discuss some of his important contributions. Atomic Theory: Whether the matter is a continuum or composed of discrete indivisible particles was a topic of philosophical importance for very long time. It was almost accepted that matter is made of indivisible particles very long ago in many ancient philosophies. But it was a matter of faith and belief and devoid of any scientific basis until a scientific basis was provided by John Dalton. John Dalton through his experimental observations of chemical reactions in gaseous systems and the findings of peer scientist working on properties of the gases synthesized and proposed the great Atomic Theory, which continues to be the foundation of the modern day sciences. The salient points of Dalton’s Atomic Theory are presented below: 1. All the elements are made of tiny indivisible particle called atoms. 2. All the atoms of an element are identical. 3. Atoms of different elements have different properties like relative weights. 4. Atoms of one element can combine with those of other elements to form compounds. In a given compound the number of different types of atoms remains the same. 5. Atoms cannot be created, destroyed or divided into smaller particles in a chemical reaction rather a chemical reaction simply changes the way atoms are combined with each other. This great theory of his remains most revered and undisputed even today despite all the progresses made in science. Today, an Atom is no more indivisible – it has internal structures and is composed of particles like electrons, protons and neutrons; but it remains the most fundamental particle exhibiting all the properties of an element. With discovery of isotopes even points 2 and 3 above are not purely correct, but despite this obvious limitation, the theory remains to be revered and forms the starting chapters in the natural sciences. Dalton not only postulated that atoms of different elements differ in diameter and weight he went ahead and made attempts to carry out measurement of these attributes as well (Rouvray 1995 ).There are many claims about how he came upto this theory but it is mostly agrees that he sythesized his Atomic Theory for explaining his laws of multiple proportions (J.S.H. 1926). Therefore, it is imperative to briefly discuss the law of multiple proportions. Law of Multiple Proportion: This law was proposed by Dalton in 1803. According to this law, if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in the ratio of small whole numbers. For example, hydrogen combines with oxygen to form two compounds, namely, water and hydrogen peroxide. Hydrogen + Oxygen = Water 2g 16g 18g Hydrogen + Oxygen = Hydrogen Peroxide 2g 32g 34g Here, the masses of oxygen (i.e. 16 g and 32 g) which combine with a fixed mass of hydrogen (2g) bear a simple ratio, i.e. 16:32 or 1: 2. This law when combined with the Law of Simple Proportions proposed by Joseph Proust leads to necessity of a physical concept of an indivisible particle which Dalton termed “Atoms”. The Law of Definite Proportion is presented below: The law states that a given compound always contains exactly the same proportion of elements by weight. Proust worked with two samples of cupric carbonate — one of which was of natural origin and the other was synthetic one. He found that the composition of elements present in it was same for both the samples as shown below : % of % of % of copper oxygen carbon Natural Sample 51.35 9.74 38.91 Synthetic Sample 51.35 9.74 38.91 Thus, irrespective of the source, a given compound always contains same elements in the same proportion. The validity of this law has been confirmed by various experiments. It is sometimes also referred to as Law of definite composition. Besides his contributions in the area of the Laws of Chemical Combination and Atomic Theory; Dalton gave another very important Law of Partial Pressures. The law states that partial pressure of a gas is proportional to its mole fraction. This law is of great value in solving the problems in the gaseous systems. Another great contribution is his pioneering work in the area of Color Blindness. It is surprising that he could do such a detailed analytical work in this field despite himself being a color blind. This shows another great side of his personality. He took motivation from one of his own disability or deficiency to understand the mechanism of vision and to utilize this understanding in explaining such an important aspect of our vision. Mostly people get depressed with their own deficiency / disability but a scientific mind takes that as motivation as evident from this example of John Dalton. When he described his own vision in one of his lectures and papers he said what others said red was a mere shade or defect of light and orange, yellow and green were nothing but different shades of yellow for him. He postulated that shortage in color perception in some people were due to discoloration of the liquid medium of the eyeball. Though his postulates proved wrong in subsequent studies; his work was so systematic and forceful that this deficiency was recognized on official level for the first time. His eye balls were preserved and have been studied recently in 1995. These studies have confirmed that he indeed had a less common type of colorblindness in which central colors are not distinguished by eye. Due to his pioneering contributions in this area color blindness was named as Daltonism (Mackenzie 1902). Summary: John Dalton’s life and work has been briefly discussed in this paper. It can be said that he was a personality with great intellectual abilities and scientific attitude and he made innumerable contributions to the area of scientific philosophy. Reference Rouvray D. H., Endeavour, Volume 19, Issue 2, 1995, Pages 52-57 J.S.H. Journal of the Franklin Institute, Volume 202, Issue 1, July 1926, Page 125 Mackenzie A. Journal of the Franklin Institute, Volume 153, Issue 6, June 1902, Pages 451-468 Read More