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
Organisation for the Prohibition of Chemical Weapons Organisation for the Prohibition of Chemical Weapons The Organisation for the Prohibition of Chemical Weapons (OPCW) is an intergovernmental organisation and the implementing body for the Chemical Weapons Convention, which entered into force on 29 April 1997. The OPCW, with its 193 member states, has its seat in The Hague, Netherlands, and oversees the global endeavour for the permanent and verifiable elimination of chemical weapons. The organisation promotes and verifies the adherence to the Chemical Weapons Convention, which prohibits the use of chemical weapons and requires their destruction. Verification consists both of evaluation of declarations by member states and onsite