Atom the truth part 1

The TRUTH BEHIND  ATOM……

              Probably the word atom is used widely in science and it is the term which is known to everyone engaged with science. This term has been very complicated to understand it that what is atom? How it exists? How it looks like? And many more questions which are annoying us and totally the world of science. It is small in size having a diameter of 0.2nm but still I am right to say that we actually don’t know much about it. The mystery of atom is tried to be solved by many scientists through their models but unfortunately there are many things to be understood.

                        What is Atom:

           Our ideas about atom has been changing with time to time, at first it was thought to be indivisible from which its name was taken as Atomos (which means indivisible) from which the word atom was derived. This idea about atom was given at the time of Democritus (460-370 B.C.) After the famous experiments of sir William Crook from England and sir Gold Stein from Germany on cathode ray tube which gave a way for the discovery of the subatomic particles i.e. electron and proton. Our perspective about atom was changed. Now we know that the ancient idea about the atom was wrong now we know that atom is divisible and it can be divided into subatomic particles i.e. electron, proton. In 1930 James Chadwick discovered another fundamental particle, the neutron. For his work he was awarded Nobel prize in 1935.

                     Today we know that matter is composed of atoms which has more than 100 particles in it like hypron, neutrino, antineutrino, etc. Out of which electron carrying negative charge proton carrying positive charge and neutron having no charge are the fundamental particles.

         Atom is defined as the smallest particle of an element which has all the properties of the element or which can show the properties of the entire element within a chemical reaction.

           A typical atom has two parts nucleated and extra nucleated part. The nucleated part contains the nucleus which contains the neutron and proton while the extra nucleated part contains the orbits or shell in which electrons revolve around the nucleus. The force which compels the electron to move in a circular path is the electrostatic force of attraction which exists between electrons in the orbits and the protons in the nucleus. A particular atom belonging to a particular element contain particular number of the subatomic particles this is why atoms are differentiated from each other. For example the number of proton, electron and neutron in Hydrogen atom is different to that of Helium but every atom has same number of electron and proton that’s why an atom is electrically neutral. An atom has a number which is used for its identification. its suitable analogy is like every student in a class has a roll number through which the particular student is identified. These number is called atomic number which is the total number of proton in its nucleus and it is denoted by Z. we don’t take electron or neutron because we know that electrons can be given or taken during bond formation and as well as the number of neutron is different in different atoms of the same element as the phenomena of isotopy. As an atom is the part of matter therefore it should have mass also so the mass of an atom is called atomic mass which is denoted by A which is the sum of the total number of neutron and proton. The mass of an atom is in its nucleus because the heavier particles are in nucleus. In orbits the electrons move which has negligible mass therefore while defining atomic mass we don’t talk about electron. In literature we use amu (atomic mass unit) in which we say the mass of an atom relative to others.

           Every atom is denoted by a capital letter sometimes two or more from its name in order to represent it these letters are called symbols. Like hydrogen in denoted by H, calcium is denoted by Ca, boron as B, bromine as Br, cobalt as Co, etc. Sometimes letter for symbol is taken from their latin or greek names as Sodium is denoted by Na (natrium) lead as Pb (plumbum), etc.

                     This was a short introduction on atom we will take about the related models in next column.