Definition of natural disaster : a sudden and terrible event in nature (such as a hurricane, tornado, or flood) that usually results in serious damage and many deaths The earthquake was one of the worst natural disasters of this century.
Synthesis, Chemical. the planned production of complex compounds from simpler compounds based on a knowledge of the reactantsâ chemical structure and reactivity. Chemical synthesis usually implies a sequence of several chemical processes (steps). In the early period in the development of chemistry, chemical synthesis was carried out mainly for inorganic compounds and was fortuitous in nature.
Chem. a number representing the relative position of an element in the periodic table, in which the elements are arranged in the order of their nuclear charges; a number representing the positive charge or the number of protons in the nucleus of the atom of an element: isotopes have the same atomic number but different mass numbers. noun.