The beginning of atomic power

Daily we see a great variety of things in nature– the sun, moon, and stars, mountains and seas, forests and animals– but we cannot answer the question who was the first person to think about atoms, or later on nuclear theory. Men and women who had studied the nature in depth, concluded long ago that everything is made of small particles. At the same time, perhaps the first simplifications were provided by the chemists who were able, by processes of destruction and analysis, to recognise certain specific substances which are the basic building materials of our world.

These are called elements. An element is defined as a substance which cannot be further split-up or refined by chemical analysis. It is equally wonderful that all the many hundred thousand different kinds of matter that man has found in this world, have turned out to consist of just over 90 substances or elements. In the chemical method, all matter on the earth is divided into two main groups: chemical compounds and elements, However, before this knowledge of chemistry man had been speculating on the nature of matter for hundreds of years on how the various kinds of matter are built up. In common, they had found it quite probable that each kind of matter was built up from its own absolutely identical particles, which could be further split up. For these particles, the old Greek philosophers used the name atoms.

Further, the atomic theories assumed more closely defined forms, a distinction being made between the smallest particles, of the chemical compounds, which were given the name of molecules and the smallest particles of the elements for which the name atoms was reserved. It also showed that even the smallest parts of a chemical compound must contain all those elements that make-up the compound. Like this, the fundamental fact was derived that the atoms of any given element have all exactly the same weight. This fact helped in finding the relation between the weights of the different atoms, and also of determining the precise number of atoms making up the molecules of a given compound.

While working she found that a uranium ore called pitchblende contained even stronger radiation than thorium and uranium. She called the element causing this radium. Isolating it was a major scientific achievement, for which Madame Curie was awarded a Nobel Prize in Chemistry, to go with her earlier one in Physics. It proved to be extremely useful both in research, for the study of the nature of atoms, and in medicine for the treatment of cancers also.

Historically, ancient Greece is the birthplace of the word ‘atom’, made up of the Greek word atomos, which means ‘indivisible’. Among the philosophers was took up the idea, Democritus, who belonged to ancient Greece some 2400 years ago, said that everything was made of tiny particles, or corpuscles, so small that no one could see them. The particles themselves could never change and they could not be broken down into smaller particles. He was of the view that atoms were the smallest particles that could exist. ‘Let us look at a substance like water. We may take a very small amount of it, a single drop, and with some care we may divide this drop into two tiny droplets. If it were possible to get the proper tools and equipment, we might be able to go on making tinier and tinier droplets, but could we go on forever?’ Democritus, like other philosophers believed that at a certain point, we would obtain a droplet that could not be cut into smaller parts. The smallest parts into which water could be cut were the atoms. After him, for centuries people hardly believed that atoms really existed and more people thought it as the fruit of Democritus’s imagination till the early 17^th century when the Italian scientist Galileo and the English chemist Robert Boyle indicated some further scientific facts. While Galileo said that he could explain odours and tastes by supposing that some substances dissolve into small corpuscles and these corpuscles might hit sensitive spots in our tongues and nostrils, and create the familiar sensation, Robert Boyle (1627-1691), held that air, and all other gases behaved as if they were made of corpuscles. Gradually, more and more facts were being explained by admitting that atoms existed. Although Robert Boyle primarily studied the expansion and compression of air, with chemistry students still studying his Law on gas behavior, with him atomism entered a new phase, from mere reasoning to experimental observations.

The atom-related facts were further developed by John Dalton who first expressed a scientific atomic theory. Before his birth, chemists had come to recognise the fact that while they could separate some substances into simpler substances, there were others they could never separate. It divided the substance into chemical elements and chemical compounds. Such substances as water, salt and sugar which are made of more than one element, were called chemical compounds, while the simple substances, such as hydrogen, oxygen, carbon, chlorine, and sodium were given the name chemical elements.

In chemistry, Dalton had observed that compound substances like water were made up of simple substances in proportions which remained invariable. No matter how small a quantity of a compound was considered, the components were always present in the same fixed proportion by weight. Dalton assumed that finally the fundamental components, in spite of their being imperceptible, must retain their characteristics in relative proportions. He called the basic units ‘atoms’ and made the further assumption that atoms of one element are all identical in mass, while different elements have atoms of different mass. The determination of the proportions of the weight of the different elements in every possible chemical compound gave the chemist a means of finding the relation between the weights of the different atoms and also of determining the precise number of atoms making up the molecules of a given compound.

Dalton’s atomic theory was really a hypothesis, but it proved very useful in summarising a large number of quantitative data which had been obtained as the result of chemical experiments. Although Dalton’s theory was correct on the whole, yet like Democritus he continued to say that atoms are the smallest particles into which matter divides– that atoms are indivisible. A little later the work of several physicists proved that atoms can break down into smaller pieces.

In the sphere of atoms a breakthrough came in early 1896 in Paris, when the French physicist Henri Becquerel in course of testing a number of phosphorescent substances found by accident, that when a phosphorescent uranium salt is glowing, it gives off not only light but also another radiation. A few days later he discovered that the uranium salt could give off the more penetrating radiation even if it is not exposed to sunlight. The experiment encouraged the scientist to test many other substances containing uranium. Then he concluded that uranium was the element that gave off radiation spontaneously.

The further work on radiation was done by Poland-born French lady scientist Madame Marie Curie, who discovered other elements that behaved like uranium. Madame Curie did her hard work on radiation and searched several other elements —thorium, polonium and ultimately radium, that gave off spontaneous radiation. While working she found that a uranium ore called pitchblende contained even stronger radiation than thorium and uranium. She called the element causing this radium. Isolating it was a major scientific achievement, for which Madame Curie was awarded a Nobel Prize in Chemistry, to go with her earlier one in Physics. It proved to be extremely useful both in research, for the study of the nature of atoms, and in medicine for the treatment of cancers also.