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  2. Selenium - Wikipedia

    en.wikipedia.org/wiki/Selenium

    Electron configuration 3d 10 4s 2 4p 4: ... 75 Se synth 119.8 d: ε: 75 As: γ – ... Selenium is a chemical element; it has the symbol Se and atomic number 34. It ...

  3. Isotopes of selenium - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_selenium

    The isotope selenium-75 has radiopharmaceutical uses. For example, it is used in high-dose-rate endorectal brachytherapy, as an alternative to iridium-192. [8]In paleobiogeochemistry, the ratio in amount of selenium-82 to selenium-76 (i.e, the value of δ 82/76 Se) can be used to track down the redox conditions on Earth during the Neoproterozoic era in order to gain a deeper understanding of ...

  4. Electron configurations of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Electron_configurations_of...

    This page shows the electron configurations of the neutral gaseous atoms in their ground states. For each atom the subshells are given first in concise form, then with all subshells written out, followed by the number of electrons per shell. For phosphorus (element 15) as an example, the concise form is [Ne] 3s 2 3p 3.

  5. Properties of nonmetals (and metalloids) by group - Wikipedia

    en.wikipedia.org/wiki/Properties_of_nonmetals...

    Selenium has a hexagonal polyatomic (CN 2) crystalline structure. It is a semiconductor with a band gap of 1.7 eV, and a photoconductor meaning its electrical conductivity increases a million-fold when illuminated. Selenium has a moderate ionisation energy (941.0 kJ/mol), high electron affinity (195 kJ/mol), and high electronegativity (2.55).

  6. Electron configuration - Wikipedia

    en.wikipedia.org/wiki/Electron_configuration

    Electron configuration. In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. [1] For example, the electron configuration of the neon atom is 1s2 2s2 2p6, meaning that the 1s, 2s, and 2p subshells are occupied by ...

  7. Group 12 element - Wikipedia

    en.wikipedia.org/wiki/Group_12_element

    primordial element. synthetic element. Group 12, by modern IUPAC numbering, [1] is a group of chemical elements in the periodic table. It includes zinc (Zn), cadmium (Cd), mercury (Hg), [2][3][4] and copernicium (Cn). [5] Formerly this group was named IIB (pronounced as "group two B", as the "II" is a Roman numeral) by CAS and old IUPAC system ...

  8. Alkali metal - Wikipedia

    en.wikipedia.org/wiki/Alkali_metal

    Selenium: Bromine: Krypton: Rubidium: ... 75 The ns 1 configuration also results in the alkali metals having very large atomic ... The 1s 1 electron configuration of ...

  9. Periodic table (electron configurations) - Wikipedia

    en.wikipedia.org/wiki/Periodic_table_(electron...

    Grayed out electron numbers indicate subshells filled to their maximum. Bracketed noble gas symbols on the left represent inner configurations that are the same in each period. Written out, these are: He, 2, helium : 1s 2. Ne, 10, neon : 1s 2 2s 2 2p 6. Ar, 18, argon : 1s 2 2s 2 2p 6 3s 2 3p 6.