CAS Number7440-21-3
PubChem CID5461123
Atomic Radius111
Atomic Volume12.1
Atomic Weight28.086
Boiling Point3,265
Bulk Modulus
Crystal StructureTetrahedral Packing
Covalent Radius111
Electrical Resistivity
Electron Configuration[Ne] 3s2 3p2
Electrons per shell2, 8, 4
Heat of Fusion50.2
Heat of Vaporization359
Ionization Potential8.152
Magnetic Ordering
Magnetic Susceptibility
Mass Number14
Melting Point1,414
Atomic Number28
Oxidation States-4, -3, -2, -1, 1, 2, 3, 4
Poisson Ratio
Shear Modulus
Specific Heat Capacity0.705
Thermal Conductivity1.48
Van der Waals radius
Young's Modulus
Abundance in Earth's crust27%
Abundance in Universe0.07%
Si Silicon 14 28.0855 14 3 p 14 1410.0 2355.0 [Ne] 3s2 3p2 2 8 4 2.33 27% Gray Cubic: Face centered 1.9 1.916 {"1":"786.5","2":"1577.1","3":"3231.6","4":"4355.5","5":"16091","6":"19805","7":"23780","8":"29287","9":"33878","10":"38726","11":"45962","12":"50502","13":"235196","14":"257923"} 780 133.6 111 ±4 1.32 12.1 50.2 359.0 0.7 148.0 0 Solid, Diamagnetic, Semiconductor, Stable, Natural, Metalloid SIL-i-ken Amorphous form is brown power; crystalline form has gray metallic appearance. Seventh most abundant element in the universe. Second most plentiful element in the earths crust. Used in glass as silicon dioxide (SiO2). Silicon carbide (SiC) is one of the hardest substances known and used in polishing. Also the crystalline form is used in semiconductors. Makes up major portion of clay, granite, quartz (SiO2), and sand. Commercial production depends on a reaction between sand (SiO2) and carbon at a temperature of around 2200 °C. a2aWO5cL410 Silicon
Roentgenium was first synthesized by an international team led by Sigurd Hofmann at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung) in Darmstadt, Germany in 1994.

The team bombarded a target of bismuth-209 with accelerated nuclei of nickel-64 and detected a single atom of the isotope roentgenium-272. Named after Wilhelm Conrad Röntgen, the German physicist 14 1824 Jöns Jacob Berzelius Sweden From the Latin word "silicis" meaning "flint"

Isotopes of Roentgenium

Standard Atomic Weight


Stable Isotopes

28Si 29Si 30Si

Unstable Isotopes

22Si 23Si 24Si 25Si 26Si 27Si 31Si 32Si 33Si 34Si 35Si 36Si 37Si 38Si 39Si 40Si 41Si 42Si 43Si 44Si

Roentgenium is harmful due to its radioactivity
Roentgenium has no stable or naturally-occurring isotopes
Roentgenium is used for scientific research purposes only.