From copper-refinery anode slime: roasted with soda ash to sodium selenite, leached, acidified, and precipitated as red amorphous Se by SO2 reduction.
Research Elements Se · atomic number 34 Reactive nonmetal · period 4, group 16 [Ar] 3d10 4s2 4p4 Shells: 2, 8, 18, 6 Valence electrons: 6 in the outer shell (4s2 4p4) 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).Selenium
Electrons
How it's obtained
Natural isotopes
Isotope Relative atomic mass Abundance 74Se 73.922475934(15) 0.0089(4) 76Se 75.919213704(17) 0.0937(29) 77Se 76.919914154(67) 0.0763(16) 78Se 77.91730928(20) 0.2377(28) 80Se 79.9165218(13) 0.4961(41) 82Se 81.9166995(15) 0.0873(22)