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Minerals in Detail
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
SODIUM
Sodium - chemical details
| Symbol | Na |
| Atomic number | 11 |
| Atomic mass | 22.98977 g.mol-1 |
| Electronegativity | 0.93 (according to Pauling) |
| Density | 0.97 g.cm-3 at 20 °C |
| Melting point | 97.5 °C |
| Boiling point | 883 °C |
| Vanderwaals radius | 0.196 nm |
| Ionic radius | 0.095 (+1) nm |
| Isotopes | 3 |
| Electronic configuration | [Ne] 3s1 |
| Energy of first ionisation | 495.7 kJ.mol-1 |
| Energy of second ionisation | 4562 kJ·mol-1 |
| Energy of third ionisation | 6910.3 kJ·mol-1 |
| Standard potential | - 2.71 V |
| Discovered | 1807 - Sir Humphrey Davy |
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Sodium - Description
Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" (formerly known as ‘group IA’). It has only
one stable isotope, 23Na. Sodium quickly oxidizes in air and is violently reactive with water, so it must be stored in an inert medium, such as kerosene.
At room temperature, sodium metal is so soft that it can be easily cut with a knife. In air, the bright silvery luster of freshly exposed sodium will
rapidly tarnish. The density of alkali metals generally increases with increasing atomic number, but sodium is denser than potassium.
Compared with other alkali metals, sodium is generally less reactive than potassium and more reactive than lithium1, in accordance with "periodic law".
Sodium reacts exothermically with water: small pea-sized pieces will bounce across the surface of the water until they are consumed by it, whereas large
pieces will explode. While sodium reacts with water at room temperature, the sodium piece melts with the heat of the reaction to form a sphere, if the
reacting sodium piece is large enough.
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Sodium - Industrial applications
Sodium is used in the manufacture of ethers and organic compounds, soap, purified metals and other applications. For details on
industrial applications and impact on the environment see www.lenntech.com/Periodic-chart-elements/Na-en.htm
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Sodium - In natural form
Sodium is present in great quantities in the earth's oceans as sodium chloride (common salt). It is also a component of many minerals, and it is an
essential element for animal life. As such, it is classified as a “dietary inorganic macro-mineral.”
Sodium is the sixth most abundant element in The Earth’s crust, which contains 2,83% of sodium in all its forms. Sodium is, after chloride, the second most
abundant element dissolved in seawater. The most important sodium salts found in nature are sodium chloride (halite or rock salt), sodium carbonate (trona
or soda), sodium borate (borax), sodium nitrate and sodium sulfate. Sodium salts are found in seawater (1.05%), salty lakes, alkaline lakes and mineral
spring water.
The production of salt is around 200 million tonnes per year; this huge amount is mainly extracted from salt deposits by pumping water down bore holes to
dissolve it and pumping up brine.The sun and many other stars shine with visible light in which the yellow component dominates and this is given out by
sodium atoms in a high-energy state.
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Sodium - Impact on health
Sodium ions (often referred to as just "sodium") are necessary for regulation of blood and body fluids, transmission of nerve impulses, heart activity, and
certain metabolic functions. Interestingly, although sodium is needed by animals, which maintain high concentrations in their blood and extracellular fluids,
the ion is not needed by plants, and is generally phytotoxic. A completely plant-based diet, therefore, will be very low in sodium. This requires some
herbivores to obtain their sodium from salt licks and other mineral sources. The animal need for sodium is probably the reason for the highly-conserved
ability to taste the sodium ion as "salty." Receptors for the pure salty taste respond best to sodium, otherwise only to a few other small monovalent
cations (Li+, NH4+, and somewhat to K+). Calcium ion (Ca2+) also tastes salty and sometimes bitter to some people but like potassium, can trigger other
tastes.
Sodium ions play a diverse and important role in many physiological processes. Excitable animal cells, for example, rely on the entry of Na+ to cause a
depolarization. An example of this is signal transduction in the human central nervous system, which depends on sodium ion motion across the nerve cell
membrane, in all nerves.
Sodium is the primary cation (positive ion) in extracellular fluids in animals and humans. These fluids, such as blood plasma and extracellular fluids in
other tissues, bathe cells and carry out transport functions for nutrients and wastes. Sodium is also the principal cation in seawater, although the
concentration there is about 3.8 times what it is normally in extracellular body fluids.
Although the system for maintaining optimal salt and water balance in the body is a complex one, one of the primary ways in which the human body keeps track
of loss of body water is that osmoreceptors in the hypothalamus sense a balance of sodium and water concentration in extracellular fluids. Relative loss of
body water will cause sodium concentration to rise higher than normal, a condition known as hypernatremia. This ordinarily results in thirst. Conversely, an
excess of body water caused by drinking will result in too little sodium in the blood (hyponatremia), a condition which is again sensed by the hypothalamus,
causing a decrease in vasopressin hormone secretion from the posterior pituitary, and a consequent loss of water in the urine, which acts to restore blood
sodium concentrations to normal.
Severely dehydrated persons, such as people rescued from ocean or desert survival situations, usually have very high blood sodium concentrations. These must
be very carefully and slowly returned to normal, since too-rapid correction of hypernatremia may result in brain damage from cellular swelling, as water
moves suddenly into cells with high osmolar content.
Sodium is essential, but controversy surrounds the amount required. Too much sodium can damage our kidneys and increases the chances of high blood pressure.
Despite the aforementioned controversy, it is generally agreed that a typical "Western" diet contains excessive amounts of sodium.
Reference:
- Prof. N. De Leon. Reactivity of Alkali Metals. Indiana University Northwest. Retrieved 24 Sep 2008.
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