WebElements Periodic Table of the Elements | Periodicity | Accurate mass of the the isotopes | periodicity

	accurate mass of the the isotopes Units None This gives the accurate masses of naturally occurring isotopes for each element. Notes The values in brackets are uncertainties in the values. Literature sources I. Mills, T. Cvitas, K. Homann, N. Kallay, and K. Kuchitsu in Quantities, Units and Symbols in Physical Chemistry, Blackwell Scientific Publications, Oxford, UK, 1988. WebElements Shop WebElements now has an online chemistry shop at which you can buy periodic table posters, mugs, T-shirts, games, molecular models, and more.
Periodicity		Search WebElements Search Chemistry Web Custom Search Essential data Essential data: name, symbol, atomic number, and atomic weight; block, period, group number, and group name in periodic table; description; standard state; registry number; and isolation History: meaning of name; discovery; and history of the element Find a property The elements round us Uses Geology: Abundance of elements in the universe; the sun; meteorites; Earth's crust; oceans; and streams Biology: abundance in humans; biological role; and health hazards Compounds Compounds: halides, oxides, sulfides, hydrides, and complexes; lattice energies; and reduction potentials Reactions of : reactions with air; water; halogens; acids; and bases Electronegativities: Pauling; Sanderson; Allred-Rochow; Mulliken-Jaffe; and Allen Bond enthalpies of diatomic species Lattice energies: oxides and halides Element properties Physics properties: boiling point; melting point; density; and molar volume; thermal conductivity; and electrical resistivity; bulk modulus; critical temperature; superconductivity temperature; hardness (mineralogical, Brinell, and Vickers); linear expansion coefficient; Poisson's ratio; reflectivity; refractive index; rigidity modulus; Young's modulus; and velocity of sound Images Allotropes Crystal structure Thermochemistry: enthalpies of atomisation, fusion, and vaporisation, thermodynamic properties Atom properties Electronic properties: electronic configuration; term symbol; electron affinity; ionisation energies; and atomic spectra Atom sizes: atomic radii; Shannon and Pauling Ionic radii; covalent radius; metallic radius; element bond length; and Van der Waals radius Electron shell properties: effective nuclear charge; electron binding energies; and valence orbital radii maxima Nuclear properties Isotopes: isotope abundances; radioactive isotopes; isotope masses; nuclear spins; and nuclear magnetic moments NMR properties: frequencies; NMR isotopes; magnetogyric ratios; quadrupole moments; receptivities; and relative sensitivities