Sodium nitride is the
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
with the
chemical formula
In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
Na
3N. In contrast to
lithium nitride
Lithium nitride is a compound with the formula Li3N. It is the only stable alkali metal nitride. The solid has a reddish-pink color and high melting point.
Preparation and handling
Lithium nitride is prepared by direct combination of elemental li ...
and some other
nitride
In chemistry, a nitride is an inorganic compound of nitrogen. The "nitride" anion, N3- ion, is very elusive but compounds of nitride are numerous, although rarely naturally occuring. Some nitrides have a find applications, such as wear-resistant ...
s, sodium nitride is an extremely unstable
alkali metal
The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...
nitride
In chemistry, a nitride is an inorganic compound of nitrogen. The "nitride" anion, N3- ion, is very elusive but compounds of nitride are numerous, although rarely naturally occuring. Some nitrides have a find applications, such as wear-resistant ...
. It can be generated by combining atomic beams of
sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
and
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
deposited onto a low-temperature
sapphire
Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, vanadium, or magnesium. The name sapphire is derived via the Latin "sapphir ...
substrate.
[ ]
'Elusive Binary Compound Prepared'
''Chemical & Engineering News'' 80 No. 20 (20 May 2002)
It readily decomposes into its elements:
:
2 Na3N -> 6 Na + N2
Synthesis
Sodium nitride can be synthesized in two different ways: by the
thermal decomposition
Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is req ...
of
NaNH2 or by the direct reaction of the elements.
The most common way to successfully synthesize sodium nitride has been done by Dieter Fischer & Martin Jansen and Grigori Vajenine using the latter method. The first way is to introduce desired ratios of Na and N
2 in gas phase separately and depositing them in a vacuum chamber on a cooled substrate, which is then heated to room temperate (298 K) to crystallize.
[
The second method is to react elemental sodium with plasma activated nitrogen on a metal surface. This synthesis can be further facilitated by introducing liquid Na-K alloy to the compound with the excess liquid removed and washed with fresh alloy. The solid is then separated from the liquid using a centrifuge. However Vajenine’s method is very air-sensitive and can decompose and combust rapidly, unless exposed to a pure oxygen (O2) environment.]
Characteristics
Sodium nitride can be of reddish brown or dark blue color depending on the synthesis of the compound due to intrinsic properties.[ It shows no signs of decomposition after several weeks when at room temperature.][ The compound does not have a melting point as it decomposes back into its elemental forms as demonstrated using mass spectrometry around 360 K.][ The estimated enthalpy of formation for the compound is +64 kJ/mol.][
]
Structure
Sodium nitride seems to be about 90% ionic at room temperature, but has the band gap typical for a semiconductor.[ It adopts the anti-ReO3 structure with a simple lattice made up of NNa6 octahedra.][ This structure has been confirmed through X-ray diffraction and more recently neutron diffraction on powder and single crystals.][
]
References
{{DEFAULTSORT:Sodium Nitride
Sodium compounds
Nitrides