Sodium

General:

Name:Sodium Symbol:Na
Type:Alkali Metal Atomic weight:22.98977
Density @ 293 K: 0.971 g/cm3 Atomic volume:23.7 cm3/mol
Discovered:

In 1806 Sir Humphry Davy had discovered that chemical bonding was electrical in nature and that he could use electricity to split substances into their constituent elements. In 1807 he isolated sodium for the first time by electrolysis of molten sodium hydroxide.

The chemical symbol for sodium (Na) comes from the Latin word 'natrium' meaning hydrated sodium carbonate.

States

State (s, l, g):solid
Melting point:370.87 K (97.72 °C) Boiling point:1156 K (883 °C)

Energies

Specific heat capacity: 1.23 J g-1 K-1 Heat of atomization:107 kJ mol-1
Heat of fusion:2.598 kJ mol-1 Heat of vaporization :96.960 kJ mol-1
1st ionization energy: 495.8 kJ mol-1 2nd ionization energy:4562.4 kJ mol-1
3rd ionization energy:6912.2 kJ mol-1 Electron affinity:52.868 kJ mol-1

Oxidation & Electrons

Shells:2,8,1 Electron configuration: [Ne] 3s1
Minimum oxidation number:-1 Maximum oxidation number: 1
Min. common oxidation no.:0 Max. common oxidation no.: 1
Electronegativity (Pauling Scale): 0.93 Polarizability volume: 23.6 Å3

Appearance & Characteristics

Structure:bcc: body-centered cubic Color:silvery-white
Hardness:0.5 mohs
Harmful effects:

Sodium is considered to be non-toxic. Contact with the skin may, however, cause irritation and burns.

Characteristics:

Sodium is a soft, silvery-white metal. It is soft enough to cut with the edge of a coin.

Freshly cut surfaces oxidize rapidly in air to form a dull, oxide coating.

Sodium burns in air with a brilliant yellow flame.

Sodium floats on water, because its density is lower than water's. It also reacts vigorously with water - violently if more than a small amount of sodium meets water (see video on left) - to produce sodium hydroxide and hydrogen gas. Sodium reacts with water more vigorously than lithium and less vigorously than potassium. Explosions occur when the heat generated by the sodium-water reaction ignites the resulting hydrogen gas.


Uses:

Metallic sodium is used in the manufacture of sodamide and esters, and in the preparation of organic compounds. The metal also may be used to modify alloys such as aluminum-silicon by improving their mechanical properties and fluidity. Sodium is used to descale (smooth the surface of) metals and to purify molten metals.

Sodium vapor lamps are highly efficient in producing light from electricity and are often used for street lighting in cities.

Sodium is used as a heat transfer agent; for example, liquid sodium is used to cool nuclear reactors.

Sodium chloride (table salt, NaCl) is vital for good nutrition. Sodium ions facilitate transmission of electrical signals in the nervous system and regulate the water balance between body cells and body fluids.

Reactions

Reaction with air:vigorous, ⇒ Na2O2 Reaction with 6 M HCl:vigorous, ⇒ H2, NaCl
Reaction with 15 M HNO3:vigorous, ⇒ NaNO3, NOx Reaction with 6 M NaOH:vigorous, ⇒ H2, NaOH

Compounds

Oxide(s):Na2O Chloride(s):NaCl
Hydride(s):NaH

Radius

Atomic radius:186 pm Ionic radius (1+ ion):116 pm
Ionic radius (2+ ion):pm Ionic radius (3+ ion):pm
Ionic radius (2- ion):pm Ionic radius (1- ion):pm

Conductivity

Thermal conductivity:142 W m-1 K-1 Electrical conductivity:0.21 x 106 S cm-1

Abundance & Isotopes

Abundance earth's crust:2.4 % by weight, 2.1 % by moles
Abundance solar system:40 parts per million by weight, 2 parts per million by moles
Cost, pure: $25 per 100g
Cost, bulk:$ per 100g
Source:

Due to its high reactivity, sodium is found in nature only as a compound and never as the free element. Sodium is our planet's sixth most abundant element and it is the most abundant alkali metal. Sodium is obtained commercially by electrolysis of molten sodium chloride.

Isotopes:

Sodium has 16 isotopes whose half-lives are known, with mass numbers 20 to 35. Of these, only one is stable: 23Na.

Other

Other:

 

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