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原子番号: 5
グループ: 13 or III A
原子量: 10.811
期間: 2
CAS番号: 7440-42-8

分類

カルコゲン
ハロゲン
希ガス
ランタノイド元素
アクチノイド元素
希土類元素
プラチナグループメタル
超ウラン
いいえ安定同位体ません
固体
液体
ガス
固体 (予測)

説明 • 用途/機能

Boron compounds have been known for thousands of years, but the element was not discovered until 1808 by Sir Humphry Davy and by Gay-Lussac and Thenard. The element is not found free in nature, but occurs as orthoboric acid usually in certain volcanic spring waters and as borates in borax and colemanite. Ulexite, another boron mineral, is interesting as it is nature’s own version of “fiber optics.” Important sources of boron are the ores rasorite (kernite) and tincal (borax ore). Both of these ores are found in the Mojave Desert. Tincal is the most important source of boron from the Mojave. Extensive borax deposits are also found in Turkey. Boron exists naturally as 19.9% 10B isotope and 80.1% 11B isotope. Eleven isotopes of boron are known. High-purity crystalline boron may be prepared by the vapor phase reduction of boron trichloride or tribromide with hydrogen on electrically heated filaments. The impure, or amorphous, boron, a brownish-black powder, can be obtained by heating the trioxide with magnesium powder. Boron of 99.9999% purity has been produced and is available commercially. Elemental boron has an energy band gap of 1.50 to 1.56 eV, which is higher than that of either silicon or germanium. It has interesting optical characteristics, transmitting portions of the infrared, and is a poor conductor of electricity at room temperature, but a good conductor at high temperature. Amorphous boron is used in pyrotechnic flares to provide a distinctive green color, and in rockets as an igniter. By far the most commercially important boron compound in terms of dollar sales is Na2B4O7 · 5H2O. This pentahydrate is used in very large quantities in the manufacture of insulation fiberglass and sodium perborate bleach. Boric acid is also an important boron compound with major markets in textile fiberglass and in cellulose insulation as a flame retardant. Next in order of importance is borax (Na2B4O7 · 10H2O) which is used principally in laundry products. Use of borax as a mild antiseptic is minor in terms of dollars and tons. Boron compounds are also extensively used in the manufacture of borosilicate glasses. Other boron compounds show promise in treating arthritis. The isotope boron-10 is used as a control for nuclear reactors, as a shield for nuclear radiation, and in instruments used for detecting neutrons. Boron nitride has remarkable properties and can be used to make a material as hard as diamond. The nitride also behaves like an electrical insulator but conducts heat like a metal. It also has lubricating properties similar to graphite. The hydrides are easily oxidized with considerable energy liberation, and have been studied for use as rocket fuels. Demand is increasing for boron filaments, a high-strength, lightweight material chiefly employed for advanced aerospace structures. Boron is similar to carbon in that it has a capacity to form stable covalently bonded molecular networks. Carboranes, metalloboranes, phosphacarboranes, and other families comprise thousands of compounds. Crystalline boron (99%) costs about $8/g. Amorphous boron costs about $4/g. Elemental boron and the borates are not considered to be toxic, and they do not require special care in handling. However, some of the more exotic boron hydrogen compounds are definitely toxic and do require care. 1

• "metabolism of calcium, magnesium, hormones" 2
• "By doping silicon with an element having three valence electrons, the conductivity is also very much enhanced. Consider what happens when silicon is doped with boron. Some of the silicon atoms in the solid are replaced by boron atoms; but because each boron atom has only three valence electrons, one of the four bonds to each boron atom has only one electron in it. We can think if this as a vacancy or "hole" in the bonding orbital. An electron from a neighboring atomcan move in to occupy this hole. Then a hole would exist on the neighboring atom, and an electron from another atom can move into it. As a result of this movement, boron-doped silicon is an electrical conductor. Because a hole is an absence of an electron, it is essentially a positive charge. Boron-doped silicon is called a p-type semiconductor, because the charge is carried by positive holes. The semiconductor behavior of doped silicon also can be explained in molecular orbital terms." 3

物理的特性

融点:4*  2075 °C = 2348.15 K = 3767 °F
沸点:4* 4000 °C = 4273.15 K = 7232 °F
昇華点:4 
三重点:4 
臨界点:4 
密度:5  2.34 g/cm3

* - at 1 atm

電子構成

電子構成: [He] 2s2 2p1
ブロック: p
最高占有エネルギーレベル: 2
ヴァランス電子: 3

量子数:

n = 2
ℓ = 1
m = -1
ms = +½

ボンディング

電気陰性度 (ポーリングスケール):6 2.04
Electropositivity (ポーリングスケール): 1.96
電子親和力:7 0.279723 eV
酸化状態: +3
仕事関数:8 4.75 eV = 7.6095E-19 J

イオン化ポテンシャル   eV 9  kJ/mol  
1 8.29803    800.6
イオン化ポテンシャル   eV 9  kJ/mol  
2 25.15484    2427.1
3 37.93064    3659.7
イオン化ポテンシャル   eV 9  kJ/mol  
4 259.37521    25025.9
5 340.2258    32826.8

熱化学

比熱: 1.026 J/g°C 10 = 11.092 J/mol°C = 0.245 cal/g°C = 2.651 cal/mol°C
熱伝導率: 27 (W/m)/K, 27°C 11
融解熱: 50.2 kJ/mol 12 = 4643.4 J/g
気化熱: 489.7 kJ/mol 13 = 45296.5 J/g
物質の状態 生成エンタルピー (ΔHf°)14 エントロピ (S°)14 ギブズ自由エネルギー (ΔGf°)14
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 1.40 5.8576 0 0
(g) 134.5 562.748 36.65 153.3436 124.0 518.816

同位体

核種 質量 15 人生の半分 15 核スピン 15 結合エネルギー
10B 10.0129370(4) STABLE 3+ 65.62 MeV
11B 11.0093054(4) STABLE 3/2- 76.49 MeV
12B 12.0143521(15) 20.20(2) ms 1+ 79.90 MeV
13B 13.0177802(12) 17.33(17) ms 3/2- 85.18 MeV
14B 14.025404(23) 12.5(5) ms 2- 85.80 MeV
15B 15.031103(24) 9.87(7) ms 3/2- 88.28 MeV
16B 16.03981(6) <190E-12 s [<0.1 MeV] 0- 88.90 MeV
17B 17.04699(18) 5.08(5) ms (3/2-) 90.45 MeV
18B 18.05617(86)# <26 ns (4-)# 89.21 MeV
19B 19.06373(43)# 2.92(13) ms (3/2-)# 90.76 MeV
6B 6.04681(75)# 0.92 MeV
7B 7.02992(8) 350(50)E-24 s [1.4(2) MeV] (3/2-) 24.74 MeV
8B 8.0246072(11) 770(3) ms 2+ 37.74 MeV
9B 9.0133288(11) 800(300)E-21 s [0.54(21) keV] 3/2- 56.34 MeV
値は、#は、純粋に実験データから派生しますが、少なくとも部分的に体系的な傾向からしていないとマーク。弱い代入引数は括弧で囲まれていてスピン。 15

反応

豊富

地球 - ソース化合物: oxides 17
地球 - 海水: 4.44 mg/L 18
地球 -  地殻:  10 mg/kg = 0.001% 18
地球 -  合計:  9.6 ppb 19
マーキュリー(惑星) -  合計:  0.11 ppb 19
金星 -  合計:  10.0 ppb 19
コンドライト - 合計: 6.2 (relative to 106 atoms of Si) 20
人体 - 合計: 0.00007% 21

化合物

安全情報


安全データシート - ACI Alloys, Inc.

詳細については

外部リンク:

ソース

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:6.
(2) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 926.
(3) - Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 394.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(6) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(8) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(13) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(14) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(15) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(16) - Atkins, Jones, and Laverman. Chemical Principles 6th ed.; W.H. Freeman and Company: New York, NY, 2013; p F94.
(17) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(18) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(19) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(20) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.
(21) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 7:17.