What is The Structure of an Atom?

            According to the ancient philosophers, every substance was believed to comprise very small particles, but due to lack of scientific knowledge they could not prove it. John Dalton was the first scientist who propounded the ‘Atomic Theory’ in 1801. According to this theory, every element is made up of very small particles called atoms. Atom is a Greek word, which means, ‘that cannot be cut’ (A means not ad tom mean cut).

The Structure of an Atom

            Atom can neither be created nor be destroyed. Atoms of the same element are similar but atoms of different elements differ. Dalton has been proved wrong by modern researchers. It has now been established, that an atom is not the smallest particle of element. In fact, it is made up of still smaller particles.

            The structure of the atom can be compared to our solar system. Like the planets revolving around the sun, the negatively charged electrons revolve around the positively charged nucleus in different orbits. Almost the entire mass of the atom is concentrated in the nucleus. The nucleus is made up of two types of particles called ‘protons’ and neutrons.

            Protons are positively charged particles, while neutrons are neutral particles. Protons and neutrons are held together in the nucleus by short range attractive nuclear force.

            Electrons revolve around the nucleus in different circular or elliptical orbits. The number of electrons, which ca go in the first orbit is two; in the second, eight; in the third, eighteen; in the fourth, thirty two ad so on. The electrons in the outermost orbit are called valence electrons. The properties of any element depend upon the number of valence electrons. When energy is given to an atom, the electrons in the outermost orbit absorb it and are excited to the higher orbits. When they fall back to their original orbit, emission or radiations takes place.

            Today, it is possible to split the atom. The atom bomb is the result of this new discovery. Splitting of atom is called nuclear fission, and this process is used for generating electric power in atomic power plants.

Can Matter be converted into Energy?

            In 1995 Albert Einstein established a relationship between mass and energy which is known as the mass-energy relation formula. According to this formula if a mass m is converted into energy, then e=mc2 where E is the energy released and C is the velocity of light. According to this formula the energy available by the conversion of half a pound of matter will be equal to that produced by exploding 7 million tones of dynamite.

Atom Bomb converts Matter into Energy

            Scientists realized the real importance of the mass energy relationship in 1945, when the first atom bomb converting uranium into energy was exploded by U.S.A. on 6 august 1945, the uranium atom bomb was dropped on Hiroshima in Japanese. There days later a plutonium atom bomb killed millions of Nagasaki. These bombs killed millions of people. Scientists realized the true potential of unclear energy. Subsequently on the basis of this formula, more powerful hydrogen bombs were developed.

             After seeing the great destruction in Hiroshima and Nagasaki scientists thought of tapping this energy for peaceful purposes. Nuclear power plants have been developed to generate electricity on the basis of this formula. Heat energy produced in reactors by the fission of uranium is used for converting water into steam to run turbines which in turn run generators. These generators produce millions of megawatts of electric power. Einstein mass energy relationship and its subsequent practical applications have proved to be a great boon to mankind. About 1% energy needs of the world are now met by nuclear energy.

What is an Atom Bomb?

You must have heard of an Atom Bomb. But do you know how it works?

            An atom bomb is a nuclear weapon, which triggers a huge explosion powerful enough to destroy a city. The reactions in an atom bomb are based on uncontrolled fission chain reaction. When a neutron bombards the nucleus of a heavy element like uranium, it breaks into two large fragments and two or three fresh neutrons are produced. These neutrons further collide with other uranium nuclei causing more fission to take place. In this process, large amounts of energy are released. If the chain reaction continues, a tremendous, devastating explosion takes place. This is what is known as an atomic explosion.

Robert OPPenheimer, the father of Atom Bomb

When critical mass of uranium-235 or plutonium-239 undergoes fission chain reaction with the help of stray neutrons, a tremendous amount of energy is released. This is how an atom bomb is made.

Reactions in an Atom Bomb

            Based on fission chain reaction, the first atomic bomb was developed during the Second World War by a team of American scientists. J. Robert Oppenheimer was the head of this team. The first atom bomb made of uranium-235, was tested on July 16, 1945 under his supervision at Alamogordo, New Mexico. Another bomb was dropped three days later on august 9, the second bomb based on plutonium was dropped on Nagasaki—both cities in Japan. These were history of mankind. Destruction caused by these bombs led to japans surrenders, and ended the Second World War. After this incident, Russia, Britain, china and France also tested their atom bombs. The French atomic bomb tested on Mururoa Atoll in the South Pacific is suspected to have caused cancer of the larynx in the people of Polynesia.