Chemical element whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than 1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element. Chemists and nuclear scientists have different definitions of a "pure element". In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the
Tre- (place name element) Tre- (place name element) Tre- is a place name element of Celtic origin meaning "hamlet, farmstead, estate", etc. which survives mainly in Wales and in the Southwest of England (almost exclusively in Cornwall). The manor of Trefusis was thus originally held before the Norman Conquest of 1066 by an Anglo-Saxon named "Fusis" or similar, thus "Farmstead of Fusis". The Cornish place-name beginning "Tre-" may be compared to the Cornish place-name beginning "Bod-" and the place-name endings "-worthy" and "-cot" in Devon, and "-ham" and "-tun / -ton" throughout England. In a study by Oliver Padel of surviving place names in