Boron
Boron ek chemical element hae jiske chemical symbol B, aur atomic number 5 hae.
| Boron | |||||||||||||||
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| 5B | |||||||||||||||
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| Boron in the periodic table | |||||||||||||||
| Appearance | |||||||||||||||
black-brown Boron, shown here in the form of its β-rhombohedral phase (its most thermodynamically stable allotrope) | |||||||||||||||
| General properties | |||||||||||||||
| Name, symbol, number | boron, B, 5 | ||||||||||||||
| Pronunciation | /ˈbɔːrɒn/ | ||||||||||||||
| Element category | metalloid | ||||||||||||||
| Group, period, block | Template:Infobox element/group, 2, p | ||||||||||||||
| Standard atomic weight | 10.81(1) | ||||||||||||||
| Electron configuration | [He] 2s2 2p1 2, 3 | ||||||||||||||
| Physical properties | |||||||||||||||
| Phase | solid | ||||||||||||||
| Liquid density at m.p. | 2.08 g·cm−3 | ||||||||||||||
| Melting point | 2349 K, 2076 °C, 3769 °F | ||||||||||||||
| Boiling point | 4200 K, 3927 °C, 7101 °F | ||||||||||||||
| Heat of fusion | 50.2 kJ·mol−1 | ||||||||||||||
| [[Enthalpy of vaporization|Heat of Template:Engvar]] | 508 kJ·mol−1 | ||||||||||||||
| Molar heat capacity | 11.087 J·mol−1·K−1 | ||||||||||||||
| [[Vapor pressure|Template:Engvar pressure]] | |||||||||||||||
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| Atomic properties | |||||||||||||||
| Oxidation states | 3, 2, 1 (mildly acidic oxide) | ||||||||||||||
| Electronegativity | 2.04 (Pauling scale) | ||||||||||||||
| [[ionization energy|Template:Engvar energies]] (more) | 1st: 800.6 kJ·mol−1 | ||||||||||||||
| 2nd: 2427.1 kJ·mol−1 | |||||||||||||||
| 3rd: 3659.7 kJ·mol−1 | |||||||||||||||
| Atomic radius | 90 pm | ||||||||||||||
| Covalent radius | 84±3 pm | ||||||||||||||
| Van der Waals radius | 192 pm | ||||||||||||||
| Miscellanea | |||||||||||||||
| Crystal structure | Template:Infobox element/crystal structure wikilink | ||||||||||||||
| Magnetic ordering | diamagnetic | ||||||||||||||
| Electrical resistivity | (20 °C) ~106 Ω·m | ||||||||||||||
| Thermal conductivity | 27.4 W·m−1·K−1 | ||||||||||||||
| Thermal expansion | (25 °C) (β form) 5–7 µm·m−1·K−1 | ||||||||||||||
| Speed of sound (thin rod) | (20 °C) 16,200 m·s−1 | ||||||||||||||
| Mohs hardness | ~9.5 | ||||||||||||||
| CAS registry number | 7440-42-8 | ||||||||||||||
| History | |||||||||||||||
| Discovery | Joseph Louis Gay-Lussac and Louis Jacques Thénard (30 June 1808) | ||||||||||||||
| First isolation | Humphry Davy (9 July 1808) | ||||||||||||||
| Most stable isotopes | |||||||||||||||
| Main article: Isotopes of boron | |||||||||||||||
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Chhapa ke gallery
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Crystalline Boron -
Flame test -
Flame test -
Kyselina trihydrogenboritá - H3BO3
References
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