Air is liquefied and fractionally distilled: O2 collects at the bottom of the column at 90 K.
Research Elements O · atomic number 8 Reactive nonmetal · period 2, group 16 [He] 2s2 2p4 Shells: 2, 6 Valence electrons: 6 in the outer shell (2s2 2p4) Green dots are the outer shell's s and p electrons. Softer green dots are the d electrons of transition metals, and the d and f electrons of lanthanides and actinides: they often take part in bonding, but not always. Grey dots are the core. Ground-state configuration from the NIST Atomic Spectra Database (A. Kramida, Yu. Ralchenko, J. Reader and the NIST ASD Team). Abundance is the mole fraction of the element found as that isotope on Earth; digits in parentheses are the uncertainty in the last digits. Masses and abundances from NIST, Atomic Weights and Isotopic Compositions (J. S. Coursey, D. J. Schwab, J. J. Tsai and R. A. Dragoset, National Institute of Standards and Technology).Oxygen
Electrons
How it's obtained
Natural isotopes
Isotope Relative atomic mass Abundance How this isotope is separated 16O 15.99491461957(17) 0.99757(16) 17O 16.99913175650(69) 0.00038(1) Cryogenic distillation of liquid water in tall columns: H2¹⁷O boils about 0.3 K higher than H2¹⁶O, so ¹⁷O enriches at the bottom. 18O 17.99915961286(76) 0.00205(14) Cryogenic distillation of liquid water at reduced pressure: H2¹⁸O boils about 0.6 K higher than H2¹⁶O, so ¹⁸O enriches at the bottom of very tall columns. Enriched water is bombarded with protons in a cyclotron to make ¹⁸F for PET scans. Molecules
Compounds