The melting (98 ☌) and boiling (883 ☌) points of sodium are lower than those of lithium but higher than those of the heavier alkali metals potassium, rubidium, and caesium, following periodic trends down the group. Due to having low atomic mass and large atomic radius, sodium is third-least dense of all elemental metals and is one of only three metals that can float on water, the other two being lithium and potassium. Mmass of sodium free#Sodium metal can be easily cut with a knife and is a good conductor of electricity and heat because it has only one electron in its valence shell, resulting in weak metallic bonding and free electrons, which carry energy. Sodium at standard temperature and pressure is a soft silvery metal that combines with oxygen in the air and forms grayish white sodium oxide unless immersed in oil or inert gas, which are the conditions it is usually stored in. In nerve cells, the electrical charge across the cell membrane enables transmission of the nerve impulse-an action potential-when the charge is dissipated sodium plays a key role in that activity.Įmission spectrum for sodium, showing the D line. Isotonic loss of water and sodium from the ECF compartment decreases the size of that compartment in a condition called ECF hypovolemia.īy means of the sodium-potassium pump, living human cells pump three sodium ions out of the cell in exchange for two potassium ions pumped in comparing ion concentrations across the cell membrane, inside to outside, potassium measures about 40:1, and sodium, about 1:10. Loss of water from the ECF compartment increases the sodium concentration, a condition called hypernatremia. Sodium ions are the major cation in the extracellular fluid (ECF) and as such are the major contributor to the ECF osmotic pressure and ECF compartment volume. Sodium is an essential element for all animals and some plants. Among many other useful sodium compounds, sodium hydroxide ( lye) is used in soap manufacture, and sodium chloride ( edible salt) is a de-icing agent and a nutrient for animals including humans. Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Many salts of sodium are highly water-soluble: sodium ions have been leached by the action of water from the Earth's minerals over eons, and thus sodium and chlorine are the most common dissolved elements by weight in the oceans. Sodium is the sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspars, sodalite, and halite (NaCl). The free metal does not occur in nature, and must be prepared from compounds. Sodium is an alkali metal, being in group 1 of the periodic table. It is a soft, silvery-white, highly reactive metal. Sodium is a chemical element with the symbol Na (from Latin natrium) and atomic number 11.
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