|
General |
Name, Symbol, Number | Sodium, Na, 11 |
Series | Alkali metal |
Group, Period, Block | 1 (IA), 3 , s |
Density, Hardness | 968 kg/m3, 0.5 |
Appearance | silvery white |
Atomic Properties |
Atomic weight | 22.989770 amu |
Atomic radius (calc.) | 180 (190)pm |
Covalent radius | 154 pm |
van der Waals radius | 227 pm |
Electron configuration | [Ne]3s1 |
e- 's per energy level | 2, 8, 1 |
Oxidation states (Oxide) | 1 (strong base) |
Crystal structure | Cubic body centered |
Physical Properties |
State of matter | solid (nonmagnetic) |
Melting point | 370.87 K (207.9 °F) |
Boiling point | 1156 K (1621 °F) |
Molar volume | 23.78 ×10-3 m3/mol |
Heat of vaporization | 96.96 kJ/mol |
Heat of fusion | 2.598 kJ/mol |
Vapor pressure | 1.43×10-5Pa at 1234 K |
Speed of sound | 3200 m/s at 293.15 K |
Miscellaneous |
Electronegativity | 0.93 (Pauling scale) |
Specific heat capacity | 1230 J/(kg*K) |
Electrical conductivity | 21 106/m ohm |
Thermal conductivity | 141 W/(m*K) |
1st ionization potential | 495.8 kJ/mol |
2nd ionization potential | 4562 kJ/mol |
3rd ionization potential | 6910.3 kJ/mol |
4th ionization potential | 9543 kJ/mol |
5th ionization potential | 13354 kJ/mol |
6th ionization potential | 16613 kJ/mol |
7th ionization potential | 20117 kJ/mol |
8th ionization potential | 25496 kJ/mol |
9th ionization potential | 28932 kJ/mol |
10th ionization potential | 141362 kJ/mol |
Most Stable Isotopes |
|
SI units & STP are used except where noted. |
Sodium is a
chemical element in the
periodic table that has the symbol Na and atom number 11.
Sodium is a soft, waxy, silvery reactive
metal belonging to the
alkali metals that is abundant in natural compounds (especially
salt water and
halite[?]).
It is highly reactive, burns with a yellow flame,
oxidizes in
air and reacts violently with
water, forcing it to be kept under
oil.
Like the other
alkali metals, sodium is a soft, light-weight, silvery white, reactive element that is never found unbound in nature. Sodium floats in
water and decomposes it releasing
hydrogen and forming
hydroxide. If ground to a fine enough power, sodium will ignite spontaneously in water. However, this metal does not normally ignite in
air below 388
Kelvin.
Sodium in its metallic form is an essential component in the making of
esters and in the manufacture of
organic compounds. This alkali metal is also a component of
sodium chloride (NaCl) which is vital to
life. Other uses:
- In certain alloys to improve their structure,
- In soap (in combination with fatty acids),
- To descale (make its surface smooth) metal, and
- To purify molten metals.
NaK, an alloy of sodium and potassium, is an important heat transfer material.
Sodium (
English, soda) has long been recognized in compounds, but was not isolated until
1807 by Sir
Humphry Davy through the
electrolysis of
caustic soda. In
Medieval Europe a compound of sodium with the Medieval
Latin name of sodanum was used as a
headache remedy. Sodium's symbol, Na, comes for the
neo-Latin name for a common sodium compound named
Natrium, which comes from the
Greek nítron, a kind of natural
salt.
Sodium is relatively abundant in
stars and the D
spectral lines of this element are among the most prominent in star light. Sodium makes up about 2.6% of the
Earth's crust making it the fourth most abundant element overall and the most abundant alkali metal. It is now produced commercially through the
electrolysis of completely dry fused
sodium chloride. This method is less expensive than the previous method of electrolyzing
sodium hydroxide. Metallic sodium cost about 15 to 20 US cents per
pound in
1997 but reagent grade (ACS) sodium cost about US$35 per pound in
1990. It is the cheapest of all metals by volume.
Isolation (* follow):
Sodium chloride, better known as common salt, is the most common compound of sodium, but sodium occurs in many other
minerals, such as
amphibole,
cryolite,
halite[?],
soda niter[?],
zeolite, etc. Sodium compounds are important to the chemical,
glass, metal,
paper,
petroleum,
soap, and
textile industries. Soap is generally a sodium
salt of certain fatty acids.
The sodium compounds that are the most important to industry 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).
There are thirteen
isotopes of sodium that have been recognized. The only stable isotope is Na-23. Sodium has two
radioactive cosmogenic isotopes (Na-22,
half-life = 2.605 years; Na-24,
half-life = ~ 15 hours).
In its powdered form sodium is explosive in water and a poison combined and uncombined with many other elements.
This metal should be handled carefully at all times. Sodium cannot be maintained in an inert
atmosphere and contact with water and other substances that sodium reacts with should be avoided.