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 Ar°(B)
	[10.806, 10.821] 10.81±0.02 (pinaikli)
Boron sa talahanayang peryodiko
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
Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 8B synth 771.9 ms β+ 8Be 10B 19.6% stable 11B 80.3% stable

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.