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11 Na 22.98976928(2)

Sodium

Alkali metal
Symbol Na
Atomic Number 11
Atomic Weight 22.98976928(2)
CAS Registry ID 7440-23-5
Group Name Alkali metal
Period Number 3
Block s-block
State at STP Solid

Description

Sample of Sodium ⌕ Enlarge Image

Sodium is an alkali metal which is in the form of a silvery white solid in its natural state. Sodium is highly reactive and so it is only found in nature as a compound in other substances. Sodium has an atomic weight of 22.9897628, a melting point of 207.9 °F, and a boiling point of 1621 °F. Common uses of sodium include: in the form of sodium compounds as a table salt, baking soda, and sodium carbonate, as an ingredient in paper, soap, and paper, and as a metal used to prepare titanium.

Isolation

There are a few methods that can be used to isolate sodium. The type of isolation procedure used depends on which compounds the sodium is recovered from.

Sodium ⌕ Enlarge Image

Large amounts of pure sodium are available on a commercial basis, and so sodium is not usually isolated in a small laboratory setting. High concentrations of sodium are easily isolated from sodium chloride deposits through the simple process of evaporation; these deposits are found in large underground reserves in the form of salt mines, and in sea water.

Another sodium isolation process uses electrolysis. Electrolysis isolation of sodium is carried out using a 40% mixture of sodium chloride and a 60% mixture of calcium chloride. The mixture of sodium compounds lowers the melting point and reduces the energy needed to carry out the electrolysis step. The electrolysis of step in this process is carried out in a Downs Cell. The Downs Cell is an apparatus that was created specifically for the commercial production of metallic sodium; very small amounts of chlorine are produced as a by product of this reaction.

General

NameSodium
SymbolNa
Number11
Chemical seriesAlkali metal
Group1
Period3
Blocks
Appearancesilvery white
Standard atomic weight22.98976928(2) g·mol⁻¹
Electron configuration[Ne] 3s1
Electrons per shell2, 8, 1

Atomic Properties

Crystal structurecubic body centered
Oxidation states1 (strongly basic oxide)
Electronegativity0.93 (Pauling scale)
Ionization energies1st: 495.8 kJ·mol−1
2nd: 4562 kJ·mol−1
3rd: 6910.3 kJ·mol−1
Atomic radius180 pm
Atomic radius (calc.)190 pm
Covalent radius154 pm
Van der Waals radius227 pm

Physical Properties

Phasesolid
Density (near r.t.)0.968 g·cm−3
Liquid density at m.p.0.927 g·cm−3
Melting point370.87 K (97.72 °C, 207.9 °F)
Boiling point1156 K (883 °C, 1621 °F)
Critical point(extrapolated) 2573 K, 35 MPa
Heat of fusion2.60 kJ·mol−1
Heat of vaporization97.42 kJ·mol−1
Heat capacity(25 °C) 28.230 J·mol−1·K−1

Miscellaneous

Magnetic orderingparamagnetic
Electrical resistivity(20 °C) 47.7 nΩ·m
Thermal conductivity(300 K) 142 W·m−1·K−1
Thermal expansion(25 °C) 71 µm·m−1·K−1
Speed of sound (thin rod)(20 °C) 3200 m/s
Young's modulus10 GPa
Shear modulus3.3 GPa
Bulk modulus6.3 GPa
Poisson ratio
Mohs hardness0.5
Vickers hardness
Brinell hardness0.69 MPa