МАГНИЙ

Введение

атомный номер: 12
группа: 2 or II A
Атомный вес: 24.305
период: 3
Количество CAS: 7439-95-4

классификация

халькогеном
галоген
Благородный газ
лантаноидное
актиноидов
Редкоземельный элемент
Металлов платиновой группы
трансурановый элемент
Нет стабильных изотопов
твердое тело
жидкость
газ
твердое тело (предсказанный)

Описание • Использование / функции

Compounds of magnesium have long been known. Black recognized magnesium as an element in 1755. It was isolated by Davy in 1808, and prepared in coherent form by Bussy in 1831. Magnesium is the eighth most abundant element in the earth’s crust. It does not occur uncombined, but is found in large deposits in the form of magnesite, dolomite, and other minerals. The metal is now principally obtained in the U.S. by electrolysis of fused magnesium chloride derived from brines, wells, and sea water. Magnesium is a light, silvery-white, and fairly tough metal. It tarnishes slightly in air, and finely divided magnesium readily ignites upon heating in air and burns with a dazzling white flame. It is used in flashlight photography, flares, and pyrotechnics, including incendiary bombs. It is one third lighter than aluminium, and in alloys is essential for airplane and missile contruction. The metal improves the mechanical, fabrication, and welding characteristics of aluminum when used as an alloying agent. Magnesium is used in producing nodular graphite in cast iron,and is used as an additive to conventional propellants. It is also used as a reducing agent in the production of pure uranium and other metals from their salts. The hydroxide (milk of magnesia), chloride, sulfate (Epsom salts), and citrate are used in medicine. Dead-burned magnesite is employed for refractory purposes such as brick and liners in furnaces and converters. Organic magnesium compounds (Grignard’s reagents) are important. Magnesium is an important element in both plant and animal life. Chlorophylls are magnesium-centered porphyrins. The adult daily requirement of magnesium is about 300 mg/day, but this is affected by various factors. Great care should be taken in handling magnesium metal, especially in the finely divided state, as serious fires can occur. Water should not be used on burning magnesium or on magnesium fires. Natural magnesium contains three isotopes. Twelve other isotopes are recognized. Magnesium metal costs about $170/kg (99.99%). 1

• "(as the Mg2+ ion) plays a vital role in metabolism and muscle functions" 2
• "commonly used to produce the bright light for photographic flash units" 3
• "is a useful structural material, especially if alloyed with aluminum" 4
• "alloys having more magnesium than aluminum are used when a high strength-to-weight ratio is needed and when corrosion resistance is important, such as in aircraft and automotive parts and in lightweight tools" 5
• "It has been suggested that magnesium, an essential component in chlorophyll, is removed from pine needles by the combined effects of ozone and acids...Another harmful effect of acid rain may be that it leaches essential metal ions such as Ca2+ and Mg2+ from soil as soluble salts." 6
• "The tires on the Hummer vehicles used in the Gulf War were made blowout-proof by strong, lightweight magnesium inserts....used in photographic flash accessories and fireworks. It is very lightweight and is currently used in many alloys for building materials." 7
• "used in lightweight alloys...Mg compounds find applications in the pharmaceutical and chemical process industries." 8

Физические свойства

Температура плавления:9*  650 °C = 923.15 K = 1202 °F
Точка кипения:9* 1090 °C = 1363.15 K = 1994 °F
возгонки:9 
тройная точка:9 
Критическая точка:9 
плотность:10  1.74 g/cm3

* - at 1 atm

Электронная конфигурация

Электронная конфигурация: [Ne] 3s2
блок: s
Самый высокий уровень энергии Занято: 3
валентных электронов: 2

Квантовые числа:

n = 3
ℓ = 0
m = 0
ms = -½

Связующие

Электроотрицательность (Полинг шкала):11 1.31
Electropositivity (Полинг шкала): 2.69
сродства к электрону:12 not stable eV
Окисление Штаты: +2
Рабочая функция:13 3.66 eV = 5.86332E-19 J

ионизационный потенциал   eV 14  kJ/mol  
1 7.64624    737.7
2 15.03528    1450.7
3 80.1437    7732.7
4 109.2655    10542.5
ионизационный потенциал   eV 14  kJ/mol  
5 141.27    13630.5
6 186.76    18019.6
7 225.02    21711.1
8 265.96    25661.2
ионизационный потенциал   eV 14  kJ/mol  
9 328.06    31653.0
10 367.5    35458.4
11 1761.805    169988.3
12 1962.665    189368.3

термохимия

Удельная теплоемкость: 1.023 J/g°C 15 = 24.864 J/mol°C = 0.245 cal/g°C = 5.943 cal/mol°C
Теплопроводность: 156 (W/m)/K, 27°C 16
Теплота плавления: 8.954 kJ/mol 17 = 368.4 J/g
Теплота парообразования: 127.4 kJ/mol 18 = 5241.7 J/g
Состояние материи Энтальпия образования (ΔHf°)19 Энтропия (S°)19 Свободная энергия Гиббса (ΔGf°)19
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 7.814 32.693776 0 0
(ℓ) 2.16 9.03744 10.16 42.50944 1.46 6.10864
(g) 35.28 147.61152 35.50 148.532 27.03 113.09352

Изотопы

нуклид масса 20 Период полураспада 20 Ядерный Спин 20 энергия связи
19Mg 19.03547(27) 1/2-# 111.36 MeV
20Mg 20.018863(29) 90.8(24) ms 0+ 135.27 MeV
21Mg 21.011713(18) 122(2) ms (5/2,3/2)+ 149.86 MeV
22Mg 21.9995738(14) 3.8755(12) s 0+ 169.11 MeV
23Mg 22.9941237(14) 11.317(11) s 3/2+ 181.84 MeV
24Mg 23.985041700(14) СТАБИЛЬНЫЙ 0+ 198.30 MeV
25Mg 24.98583692(3) СТАБИЛЬНЫЙ 5/2+ 206.37 MeV
26Mg 25.982592929(30) СТАБИЛЬНЫЙ 0+ 217.23 MeV
27Mg 26.98434059(5) 9.458(12) min 1/2+ 223.44 MeV
28Mg 27.9838768(22) 20.915(9) h 0+ 232.44 MeV
29Mg 28.988600(15) 1.30(12) s 3/2+ 235.86 MeV
30Mg 29.990434(9) 335(17) ms 0+ 242.07 MeV
31Mg 30.996546(13) 230(20) ms 3/2+ 244.55 MeV
32Mg 31.998975(19) 86(5) ms 0+ 250.76 MeV
33Mg 33.005254(21) 90.5(16) ms 7/2-# 252.31 MeV
34Mg 34.00946(25) 20(10) ms 0+ 256.65 MeV
35Mg 35.01734(43)# 70(40) ms (7/2-)# 257.27 MeV
36Mg 36.02300(54)# 3.9(13) ms 0+ 259.75 MeV
37Mg 37.03140(97)# 40# ms [>260 ns] 7/2-# 260.37 MeV
38Mg 38.03757(54)# 1# ms [>260 ns] 0+ 262.86 MeV
39Mg 39.04677(55)# <260 ns 7/2-# 262.54 MeV
40Mg 40.05393(97)# 1# ms 0+ 264.10 MeV
Значения, отмеченные # не чисто получены из экспериментальных данных, но, по крайней мере, частично от систематических тенденций. Спины с аргументами слабые присваивания заключены в круглые скобки. 20

Реакции

изобилие

Земля - Исходные соединения: carbonates/sulfates 26
Земля - морская вода: 1290 mg/L 27
Земля -  корка:  23300 mg/kg = 2.33% 27
Земля -  накидка:  16.6% 28
Земля -  литосфера:  2.76% 29
Земля -  гидросфера:  0.13% 29
Земля -  Всего:  13.90% 30
Планета Меркурий) -  Всего:  6.50% 30
Венера -  Всего:  14.54% 30
вселенная -  Всего:  0.06% 28
Хондриты - Всего: 9.4×105 (relative to 106 atoms of Si) 31
Тело человека - Всего: 0.027% 32

соединений

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Внешние ссылки:

источники

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