How are the parts of the atom arranged?
The classical picture is not totally correct but is helpful in understanding the atomic structure: The atom consists of a central nucleus, which has almost all the mass of the atom in it and is made up of protons and neutrons. Protons are positively charged and neutrons are electrically neutral. Their masses are almost equal. The nucleus is surrounded by a cloud of electrons, which are of neglgible mass but have equal and opposite charge (negative) to the proton’s charge. Since the number of electrons are equal to the number of neutrons, the atom is electrically neutral. The outer electrons are relatively loosely bound to the nucleus and under the right conditions come out and take part in chemical reactions. The nuclei of heavy elements like Uranium, Thorium etc. are unstable and attain stability by a process called radioactivity, emission of particulate and electromagnetic radiation. When bombarded by neutrons, some of the heavy nuclei undergo a fission reaction (breaking into 2 frag
