# Boron

Boron, 5B| boron (β-rhombohedral) |
| Boron |
| Bigkas |  /ˈbɔːrɒn/ ​(*BOR-on*) |
| Allotropes | α-, β-rhombohedral, β-tetragonal (at marami pa) |
| Appearance | black-brown |
|  |
| Standard atomic weight *A*r°(B) |
|  | * [10.806, 10.821]
* 10.81±0.02 (pinaikli)
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|  |
| Boron sa talahanayang peryodiko |
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|  |  |  |
| --- | --- | --- |
| Hydrogen |  | Helium |
| Lithium | Beryllium |  | Boron | Carbon | Nitrogen | Oxygen | Fluorine | Neon |
| Sodium | Magnesium |  | Aluminium | Silicon | Phosphorus | Sulfur | Chlorine | Argon |
| Potassium | Calcium |  | Scandium | Titanium | Vanadium | Chromium | Manganese | Iron | Cobalt | Nickel | Copper | Zinc | Gallium | Germanium | Arsenic | Selenium | Bromine | Krypton |
| Rubidium | Strontium |  |  | Yttrium | Zirconium | Niobium | Molybdenum | Technetium | Ruthenium | Rhodium | Palladium | Silver | Cadmium | Indium | Tin | Antimony | Tellurium | Iodine | Xenon |
| Caesium | Barium | Lanthanum | Cerium | Praseodymium | Neodymium | Promethium | Samarium | Europium | Gadolinium | Terbium | Dysprosium | Holmium | Erbium | Thulium | Ytterbium | Lutetium | Hafnium | Tantalum | Tungsten | Rhenium | Osmium | Iridium | Platinum | Gold | Mercury (element) | Thallium | Lead | Bismuth | Polonium | Astatine | Radon |
| Francium | Radium | Actinium | Thorium | Protactinium | Uranium | Neptunium | Plutonium | Americium | Curium | Berkelium | Californium | Einsteinium | Fermium | Mendelevium | Nobelium | Lawrencium | Rutherfordium | Dubnium | Seaborgium | Bohrium | Hassium | Meitnerium | Darmstadtium | Roentgenium | Copernicium | Nihonium | Flerovium | Moscovium | Livermorium | Tennessine | Oganesson |

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

 |

 |
| Atomikong bilang (*Z*) | 5 |
| Group | 13 |
| Period | 2 |
| Block |   p-block |
| Electron configuration | [He] 2s2 2p1 |
| Electrons per shell | 2, 3 |
| Physical properties |
| Phase at STP | solido |
| Melting point | 2349 K ​(2076 °C, ​3769 °F)  |
| Boiling point | 4200 K ​(3927 °C, ​7101 °F)  |
| Density when liquid (at m.p.) | 2.08 g/cm3  |
| Heat of fusion | 50.2 kJ/mol  |
| Heat of vaporization | 508 kJ/mol  |
| Molar heat capacity | 11.087 J/(mol·K)  |
| **Vapor pressure**

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

 |
| Atomic properties |
| Oxidation states | −5, −1, 0, +1, +2, **+3** (isang katamtamang asidikong oksido) |
| Electronegativity | Pauling scale: 2.04  |
| Ionization energies | * 1st: 800.6 kJ/mol
* 2nd: 2427.1 kJ/mol
* 3rd: 3659.7 kJ/mol
* (more)
 |
| Atomic radius | empirical: 90 pm  |
| Covalent radius | 84±3 pm  |
| Van der Waals radius | 192 pm  |
| **Mga linyang espektral ng boron** |
| Other properties |
| Natural occurrence | primordiyal |
| Crystal structure |  ​*rhombohedral* |
| Thermal expansion | β form: 5–7 µm/(m⋅K) (at 25 °C)  |
| Thermal conductivity | 27.4 W/(m⋅K)  |
| Electrical resistivity | ~106 Ω⋅m (at 20 °C)  |
| Magnetic ordering | diamagnetic  |
| Molar magnetic susceptibility | −6.7×10−6 cm3/mol |
| Speed of sound  thin rod | 16,200 m/s (at 20 °C)  |
| Mohs hardness | ~9.5  |
| CAS Number | 7440-42-8  |
| History |
| Discovery | Joseph Louis Gay-Lussac and Louis Jacques Thénard (30 June 1808) |
| First isolation | Humphry Davy (9 July 1808) |
| Isotopes of boron* t
* b
 |
|  |
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| Main isotopes | Decay |
| --- | --- |
|  | abun­dance | half-life (*t*1/2) | mode | pro­duct |
| 8B | synth | 771.9 ms | β+ | 8Be |
| 10B | 19.6% | stable |
| 11B | 80.3% | stable |

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Ang **boro** (Ingles: *boron*) ay isang elementong kimikal sa talahanayang peryodiko na sinasagisag ng simbolong **B** at nagtataglay ng atomikong bilang **5**.

May atomikong bigat na 10.118, punto ng pagkatunaw na 2,300oC, nagkakaroon ng sublimasyon sa 2,550oC, may espesipikong grabidad na 2.34 (anyong kristalina), at balensiyang 3) ay isang hindi metalikong elemento na malambot at kakulay ng kape, at nasa anyong amorpus o kristalina. Nakukuha ang mga ito mula sa kerito at boraks. Naihiwalay ito nina Humphry Davy, Joseph Louis Gay-Lussac at Louis Jacques Thénard noong 1808 sa pamamagitan ng reaksiyon ng asidong boriko at ng potasyo. Tinawag ito ni Davy bilang *boracium*. Nagagamit ang elementong ito para sa paggawa ng mga pampasibad na kemikal, sa mga pampailaw, panggasgas, at maging para sa aloy na matitigas.

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