DeuteriumHydrogen isotope with a nucleus containing a neutron and a p... oxide, D2O; water containing two deuteriumHydrogen isotope with a nucleus containing a neutron and a p... atoms instead of the two light hydrogen atoms. Natural water contains one deuteriumHydrogen isotope with a nucleus containing a neutron and a p... atomSmallest particle of an element which cannot be chemically d... per 6,500 molecules H2O. D2O has a low neutronUncharged elementary particle with a mass of 1.67492716 ·10... absorption cross-section. It is therefore applicable as a moderatorMaterial used to "decelerate" fast neutrons to low energies,... in natural-uranium-fuelled reactors.