Sodium is defined as a chemical element of the alkali metal group (of Group 1 [Ia]) of the periodic table. The sodium element is a very soft and silvery-white metal. It is the most common alkali metal and the 6th most abundant element on Earth, comprising 2.8% of the crust of the Earth. It takes ace abundantly in nature in compounds, especially as common salt - the sodium chloride (NaCl), that forms the mineral halite and constitutes about 80% of the dissolved constituents of seawater.
The chemical formula of Sodium is given as Na and the Na chemical name is given as Sodium.
Properties of Sodium
The fastest reaction between the water and sodium is an example of intermolecular redox. Sodium reaction with air to form a sodium hydroxide film.
Principal Na Compounds
The sodium element is highly reactive and forms a wide range of compounds with nearly all organic and inorganic (negatively charged ions) anions. Its oxidation state is normally +1, and its single valence electron is colourless, yielding the colourless sodium cation (Na+). Compounds that are composed of sodium anion, Na−, have also been synthesized. The principal commercial sodium compounds are given as carbonate, sulfate, and chloride.
The most familiar and important sodium compound is common salt, or sodium chloride, NaCl. Most of the other sodium compounds are prepared either directly or indirectly from the sodium chloride, which takes place in natural brines, in seawater, and as rock salt. Excess quantities of sodium chloride are employed in other heavy (industrial) chemical production and being used directly for snow and ice removal as well, for water conditioning, and in food products.
Reactions of Sodium
Reaction with Air
Sodium is normally very reactive with air, and its reactivity is a result of the amount of water vapour in the air or the relative humidity. Also, the solid sodium’s corrosion by oxygen is accelerated by the presence of fewer amounts of impurities in the sodium. In ordinary air, though, the sodium metal reacts to create a sodium hydroxide coating, which can quickly absorb carbon dioxide from the air and form sodium bicarbonate. Since sodium metal does not react with nitrogen, it is normally held in a nitrogen setting (or in inert liquids such as naphtha or kerosene).
Significantly, it is more reactive in the air as a liquid than solid. And liquid can ignite at about 125 °C. Sodium metal softly burns in a relatively dry setting, emitting a thick white caustic smoke that can cause coughing and choking. The temperature of burning sodium rapidly increases to more than 800°C, and under such conditions, the fire is extremely difficult to extinguish. A special dry-powder fire extinguisher is required because sodium reacts with carbon dioxide, which is a common propellant in regular fire extinguishers.
Reaction with Nonmetals
In general, alkali metals react with the halogen gases, which is the degree of reactivity by decreasing with an increase in the atomic weight of the halogen. Sodium metal is no exception to this declaration. Under certain conditions of the reaction, halogen and sodium vapours react to form light (chemiluminescence). Halogen acids, like hydrochloric acid, vigorously react with sodium by yielding the sodium halides. These reactions are highly exothermic, with the reaction heats (energy is given off) of −76.2 and −71.8 kcal, respectively, for the reactions hydrochloric and hydrofluoric acids.
Sodium can be attacked by the other strong mineral acids to produce the corresponding salts. It also reacts with the nitric acid fumes at 15 °C to produce sodium nitrate and with sulfuric and acetic acids to produce sodium sulfate and sodium acetate. It reacts violently with molten sulfur to form polysulfides; it reacts with organic solutions of sulfur under more controlled conditions. Liquid tellurium and selenium both vigorously react with solid sodium to produce tellurides and selenides.
The organic reactions of sodium metal have been studied to a greater extent than those of any other alkali metals. Sodium metal reacts with anhydrous alcohols to produce respective alcoholates (or called alkoxides) as per the
Na + ROH → RONa + 1/2 H2,
where R is given as the alcohol’s organic portion (CH3CH2 for ethanol, R = CH3 for methanol, etc.). The reaction is the most vigorous one with methanol and decreases with increasing alcohol’s molecular weight. Sodium methoxide can be produced on an industrial scale by the reaction of sodium with excess methanol. Organic acids react with sodium metal to produce sodium salts.
Reaction with Metals
Sodium is completely miscible with the alkali metals down to it in the periodic table (rubidium, caesium, and potassium). A eutectic (which is an alloy that melts lower than its components) melting at a temperature of −10 °C is produced in the sodium-potassium system and is commercially known as NaK.
Its composition is around 78% of potassium, and it can be used as a heat-transfer fluid and as an organic reactant. The eutectics are produced in the sodium-caesium and the sodium-rubidium binary systems melt, at −30 °C and −4.5 °C, respectively. Sodium is a minor component with caesium and potassium of the ternary alloy NaKCs, melting at a temperature of −78 °C. This fluid is given as the lowest-melting liquid alloy yet to be isolated.