# Boron

| Boron |
| --- |
|  **5B** |
|

|  |  |  |  |
| --- | --- | --- | --- |
|

|  |  |
| --- | --- |
|  | - ↑ **B** ↓ Al |
| beryllium ← **boron** → carbon |

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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]] |
|

|  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
| P (Pa) | 1 | 10 | 100 | 1 k | 10 k | 100 k |
| at T (K) | 2348 | 2562 | 2822 | 3141 | 3545 | 4072 |

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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 |
|

| iso | NA | half-life | DM | DE (MeV) | DP
Template:Elementbox isotopes stable
Template:Elementbox isotopes stable |
| --- | --- | --- | --- | --- | --- |
| 10B content may be as low as 19.1% and as high as 20.3% in natural samples. 11B is the remainder in such cases. |

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Boron in a tube
Boron
**Boron** ek chemical element hae jiske chemical symbol **B**, aur atomic number 5 hae.

## Chhapa ke gallery

* Crystalline Boron
* Flame test
* Flame test
* Kyselina trihydrogenboritá - H3BO3

| v • d • ePeriodic table |
| --- |
| H |   | He |
| Li | Be |   | B | C | N | O | F | Ne |
| Na | Mg |   | Al | Si | P | S | Cl | Ar |
| K | Ca | Sc |   | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga | Ge | As | Se | Br | Kr |
| Rb | Sr | Y |   | Zr | Nb | Mo | Tc | Ru | Rh | Pd | Ag | Cd | In | Sn | Sb | Te | I | Xe |
| Cs | Ba | La | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu | Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg | Tl | Pb | Bi | Po | At | Rn |
| Fr | Ra | Ac | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og |
|

|  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Alkali metals | Alkaline earth metals | Lanthanide | Actinoids | Transition metals | Other metals | Metalloids | Other nonmetals | Halogens | Noble gases |

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