SODIO

introduzione

Numero atomico: 11
Gruppo: 1 or I A
Peso atomico: 22.98977
Periodo: 3
Numero CAS: 7440-23-5

Classificazione

Metallo
Metalloide
simile a metallo
metallo alcalino
Alkali terroso
Metallo di transizione
calcogeno
alogena
Gas nobile
Lanthanoid
Actinoid
Terre rare
Platinum Metal Group
transuranici
Non ci sono isotopi stabili
Solido
Liquido
Gas
Solido (previsto)

Descrizione • Usi / Funzione

Long recognized in compounds, sodium was first isolated by Davy in 1807 by electrolysis of caustic soda. Sodium is present in fair abundance in the sun and stars. The D lines of sodium are among the most prominent in the solar spectrum. Sodium is the sixth most abundant element on earth, comprising about 2.6% of the earth’s crust; it is the most abundant of the alkali group of metals of which it is a member. The most common compound is sodium chloride, but it occurs in many other minerals, such as soda niter, cryolite, amphibole, zeolite, sodalite,etc. It is a very reactive element and is never found free in nature. It is now obtained commercially by the electrolysis of absolutely dry fused sodium chloride. This method is much cheaper than that of electrolyzing sodium hydroxide, as was used several years ago. Sodium is a soft, bright, silvery metal which floats on water, decomposing it with the evolution of hydrogen and the formation of the hydroxide. It may or may not ignite spontaneously on water, depending on the amount of oxide and metal exposed to the water. It normally does not ignite in air at temperatures below 115°C. Sodium should be handled with respect, as it can be dangerous when improperly handled. Metallic sodium is vital in the manufacture of sodamide and esters, and in the preparation of organic compounds. The metal may be used to improve the structure of certain alloys, to descale metal, to purify molten metals, and as a heat transfer agent. An alloy of sodium with potassium, NaK, is also an important heat transfer agent. Sodium compounds are important to the paper, glass, soap, textile, petroleum, chemical, and metal industries. Soap is generally a sodium salt of certain fatty acids. The importance of common salt to animal nutrition has been recognized since prehistoric times. Among the many compounds that are of the greatest industrial importance are common salt (NaCl), soda ash (Na2CO3), baking soda (NaHCO3), caustic soda (NaOH), Chile saltpeter (NaNO3), di- and tri-sodium phosphates, sodium thiosulfate (hypo, Na2S2O3 · 5H2O), and borax (Na2B4O7 · 10H2O). Seventeen isotopes of sodium are recognized. Metallic sodium is priced at about $250/kg (99.95%). On a volume basis, it is the cheapest of all metals. Sodium metal should be handled with great care. It should be kept in an inert atmosphere and contact with water and other substances with which sodium reacts should be avoided. 1

• "is still important in the manufacture of many chemicals, including pharmaceuticals and dyes such as indigo." 2
• "Sodium is used in making sodium peroxide, sodium cyanide, and in the manufacture of many complex compounds used as drugs and dyes. Its activity makes it valuable for the study of typical chemical actions. The alloy of sodium with mercury (sodium amalgam) is an important reducing agent. A sodium-lead alloy is used in making ethyl gasoline. Another use for sodium is in sodium vapor lamps used to light our highways with the bright yellow light which is characteristic of sodium. The sodium is vaporized and heated to incandescence by the electric current." 3
• "The metal itself is used as a reducing agent in the manufacture of drugs and dyes and in the metallurgy of such metals as titanium and zirconium...Highway lamps often incorporate Na arcs, which produce a bright yellow glow." 4
• "Sodium chloride, from which sodium is extracted by electrolysis, can be obtained in a fairly pure form by the evaporation of seawater in large ponds." 5

Proprietà fisiche

Punto di fusione:6*  97.80 °C = 370.95 K = 208.04 °F
Punto di ebollizione:6* 883 °C = 1156.15 K = 1621.4 °F
sublimazione Point:6 
Triple Point:6 
Punto critico:6 2300 °C = 2573.15 K = 4172 °F 6
Densità:7  0.97 g/cm3

* - at 1 atm

configurazione elettronica

configurazione elettronica: [Ne] 3s1
Bloccare: s
Più alto livello di energia Occupato: 3
Elettroni di valenza: 1

numeri quantici:

n = 3
ℓ = 0
m = 0
ms = +½

bonding

elettronegatività (scala Pauling):8 0.93
Electropositivity (scala Pauling): 3.07
Affinità elettronica:9 0.547926 eV
ossidazione Uniti: +1
Funzione di lavoro:10 2.70 eV = 4.3254E-19 J

potenziale di ionizzazione   eV 11  kJ/mol  
1 5.13908    495.8
2 47.2864    4562.4
3 71.62    6910.3
potenziale di ionizzazione   eV 11  kJ/mol  
4 98.91    9543.4
5 138.4    13353.6
6 172.18    16612.8
7 208.5    20117.2
potenziale di ionizzazione   eV 11  kJ/mol  
8 264.25    25496.2
9 299.864    28932.5
10 1465.121    141362.7
11 1648.702    159075.5

Termochimica

Calore specifico: 1.228 J/g°C 12 = 28.231 J/mol°C = 0.293 cal/g°C = 6.747 cal/mol°C
Conduttività termica: 141 (W/m)/K, 27°C 13
Calore di fusione: 2.598 kJ/mol 14 = 113.0 J/g
Calore di vaporizzazione: 96.96 kJ/mol 15 = 4217.5 J/g
Stato della materia Entalpia di formazione (ΔHf°)16 entropia (S°)16 Energia libera di Gibbs (ΔGf°)16
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 12.30 51.4632 0 0
(ℓ) 0.575 2.4058 13.83 57.86472 0.119 0.497896
(g) 25.75 107.738 36.71 153.59464 18.48 77.32032

isotopi

nuclide Massa 17 Metà vita 17 spin nucleare 17 Energia di legame
18Na 18.02597(5) 1.3(4)E-21 s (1-)# 113.39 MeV
19Na 19.013877(13) <40 ns (5/2+)# 132.64 MeV
20Na 20.007351(7) 447.9(23) ms 2+ 146.30 MeV
21Na 20.9976552(8) 22.49(4) s 3/2+ 163.69 MeV
22Na 21.9944364(4) 2.6027(10) yr 3+ 174.55 MeV
23Na 22.9897692809(29) STABILE 3/2+ 187.28 MeV
24Na 23.99096278(8) 14.9590(12) h 4+ 194.42 MeV
25Na 24.9899540(13) 59.1(6) s 5/2+ 203.42 MeV
26Na 25.992633(6) 1.077(5) s 3+ 208.70 MeV
27Na 26.994077(4) 301(6) ms 5/2+ 214.91 MeV
28Na 27.998938(14) 30.5(4) ms 1+ 219.25 MeV
29Na 29.002861(14) 44.9(12) ms 3/2(+#) 223.60 MeV
30Na 30.008976(27) 48.4(17) ms 2+ 226.08 MeV
31Na 31.01359(23) 17.0(4) ms (3/2+) 229.50 MeV
32Na 32.02047(38) 12.9(7) ms (3-,4-) 231.05 MeV
33Na 33.02672(94) 8.2(2) ms 3/2+# 233.53 MeV
34Na 34.03517(96)# 5.5(10) ms 1+ 233.22 MeV
35Na 35.04249(102)# 1.5(5) ms 3/2+# 234.77 MeV
36Na 36.05148(102)# <260 ns 234.46 MeV
37Na 37.05934(103)# 1# ms [>1.5 μs] 3/2+# 235.07 MeV
I valori assegnati # non sono puramente derivati ​​da dati sperimentali, ma almeno parzialmente da tendenze sistematiche. Gira con argomenti di assegnazione deboli sono racchiusi tra parentesi. 17

reazioni

Abbondanza

Terra - composti di origine: halide salts or brines 23
Terra - L'acqua di mare: 10800 mg/L 24
Terra -  Crosta:  0.000236 mg/kg = 0.0000000236% 24
Terra -  Mantello:  0.8% 25
Terra -  Litosfera:  2.27% 26
Terra -  Idrosfera:  1.1% 26
Terra -  Totale:  1250 ppm 27
Pianeta Mercurio) -  Totale:  200 ppm 27
Venere -  Totale:  1390 ppm 27
condriti - Totale: 4.6×104 (relative to 106 atoms of Si) 28
Corpo umano - Totale: 0.14% 29

Composti

Informazioni sulla sicurezza


Scheda di sicurezza - ACI Alloys, Inc.

Per maggiori informazioni

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fonti

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(2) - Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 58.
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(4) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 924.
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