Sodium

Sodium is a chemical element with an atomic number of 11. Its symbol is Na (from its Latin name natrium). It is an alkali metal. Although sodium has many isotopes, most decay in a short time. Because of this, all sodium in nature (mainly found in seawater) is of the isotope 11Na23. The atomic mass of sodium is 22.9898.

Properties 
Sodium is a light-weight, silver-colored metal. Sodium is soft, and because of that, someone could easily cut it with a knife. When someone cuts it, the exposed part will become white over time. It reacts with air to form sodium hydroxide and sodium carbonate. Sodium is a little less dense than water; when someone puts it in water, it floats and reacts instantly, producing hydrogen and sodium hydroxide. This reaction has a lot of heat, usually causing the hydrogen to light on fire. When this happens, sodium melts because of its low melting point. Sodium is highly reactive because it has one valence electron, which is easily removed.  

Compared with other alkali metals, sodium is less reactive than potassium and more reactive than lithium.

Chemical compounds 
These are chemical compounds that contain sodium ions. Sodium only exists in one oxidation state: +1.

Sodium aluminum fluoride, used to make aluminum
Sodium amide, very strong base
Sodium arsenite, colorless solid, very toxic
Sodium arsenate, oxidizing agent, very toxic
Sodium azide, used in airbags
Sodium bicarbonate, baking soda, used in cooking
Sodium bismuthate, oxidizing agent, used to test for manganese
Sodium bisulfate, acidic, used to lower pH
Sodium bromate, oxidizing agent, used to dye hair
Sodium bromide, rare, used in some medicine
Sodium carbonate, used to make glass
Sodium chlorate, used in some explosives
Sodium chlorite, used in disinfectants
Sodium chloride, table salt
Sodium chromate, yellow, oxidizing agent, toxic
Sodium dichromate, orange, oxidizing agent, toxic
Sodium fluoride, used in toothpaste, bitter, toxic in large doses
Sodium hydroxide, lye, used in soap, strong base
Sodium hypochlorite, bleach, disinfectant
Sodium hypophosphite, reducing agent, poisonous
Sodium iodate, oxidizing agent, prevents iodine deficiency
Sodium iodide, a weak reducing agent, prevents iodine deficiency
Sodium manganate, rare green solid
Sodium nitrate, used in blasting powder
Sodium nitrite, used in food preservation
Sodium periodate, oxidizing agent
Sodium permanganate, less common than potassium permanganate, oxidizing agent
Sodium phosphate, various uses
Sodium phosphide, catalyst, used to speed up chemical reactions
Sodium phosphite, toxic, reducing agent
Sodium selenate, strong oxidizing agent, other selenium compounds
Sodium selenide, strong reducing agent, reactive
Sodium selenite, weak oxidizing agent, vitamin supplement
Sodium sulfate, bitter, laxative
Sodium sulfite, a weak reducing agent, used to preserve dried food
Sodium tellurate, strong oxidizing agent
Sodium telluride, a strong reducing agent, reacts with air easily
Sodium tellurite, main tellurite compound

Discovery and name origins 
Sodium was discovered by Sir Humphrey Davy, an English scientist, in 1807. He created it by electrolyzing sodium hydroxide. Davy named the element after soda, a name for sodium hydroxide or sodium carbonate.

Use as element 
Scientists can use it in the creation of organic compounds. People also use it in orange streetlights and lamps that emit ultraviolet light.

Use in compounds 
Sodium compounds are used in soaps, toothpaste, baking, and antacids.

Occurrence and production 
Sodium does not occur as an element in nature, because it is not stable enough. It exists only in chemical compounds. Sodium ions are found in the ocean and in the Earth's crust. 

Sodium is normally made by electrolysis of sodium chloride, which is mined from the Earth's crust.

Use in organisms 
The human body needs sodium ions, taken in the form of sodium chloride, to live, but too much of it can cause health problems. Many organisms in the ocean depend on the concentration of sodium ions in water to survive.

Related pages
 List of common elements
 Hyponatremia (a medical problem caused by not having enough sodium in the body)

References 

Alkali metals