atom is considered to be fundamental particles of the substance and is composed of a thick central portion (nucleus) with a positive electric charge surrounded by a cloud of electrons with a negative charge. Nucleus is in turn made up of protons and neutrons. Electrons in an atom are linked to the core by the electromagnetic force. Atoms can exist in the free state and to connect among themselves through chemical bond in a molecule or crystal lattice.
Hard water is water that has high mineral content (in contrast with “soft water”).
Hard drinking water is generally not harmful to one’s health, but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling towers, and other equipment that handles water. In domestic settings, hard water is often indicated by a lack of suds formation when soap is agitated in water. Wherever water hardness is a concern, water softening is commonly used to reduce hard water’s adverse effects.
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid (water or gas), which runs through turbines that power either ship’s propellers or generators. Some produce isotopes for medical and industrial use, and some are run only for research.