Tecken | B |
Atomnummer | 5 |
Grupp | 13 (Borgruppen) |
Period | 2 |
Block | p |
Ämnesklass | Halvmetall |
Utseende | Black-brown |
Färg | Svart |
Antal protoner | 5 p+ |
Antal neutroner | 6 n0 |
Antal elektroner | 5 e- |
Fas vid STP | Fast |
Densitet | 2.08 g/cm3 |
Relativ atommassa | 10.806 u |
Smältpunkt | 2349 K 2075.85 °C 3768.53 °F |
Kokpunkt | 4200 K 3926.85 °C 7100.33 °F |
Ångbildningsvärme | 507.8 kJ/mol |
Elektronegativitet (Paulingskalan) | 2.04 |
Elektronaffinitet | 26.989 kJ/mol |
Oxidationstal | −5, −1, 0, +1, +2, +3 (a mildly acidic oxide) |
Jonisationspotential |
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Upptäckt | Joseph Louis Gay-Lussac, Louis Jacques Thénard (1808) |
Första isolation | Humphry Davy (1808) |
Upptäckten av bor Boron was not recognized as an element until it was isolated by Sir Humphry Davy and by Joseph Louis Gay-Lussac and Louis Jacques Thénard. In 1808 Davy observed that electric current sent through a solution of borates produced a brown precipitate on one of the electrodes. In his subsequent experiments, he used potassium to reduce boric acid instead of electrolysis. He produced enough boron to confirm a new element and named it boracium. Gay-Lussac and Thénard used iron to reduce boric acid at high temperatures. By oxidizing boron with air, they showed that boric acid is its oxidation product. Jöns Jacob Berzelius identified it as an element in 1824. |