What is Sodium?
Sodium, like lithium and potassium, belongs to the alkali metal family. The most famous claim to fame is that it is one of the two elements that make up table salt. As sodium binds with chlorine, we get sodium chloride (NaCl). It's also used in fertilizers as a salt. Sodium is the most significant of all alkaline metals from a commercial standpoint because it is a reactive, soft metal with a low melting point. Sodium hydroxide is formed when sodium reacts quickly with water, snow, or ice.
As metallic sodium is exposed to sunlight, it loses its silver appearance and forms an opaque grey color layer of sodium oxide as a coating.Except at extremely high temperatures, sodium does not react with nitrogen, but it does react with ammonia to form sodium amide.
Over 200°C, sodium reacts with hydrogen to form sodium hydride. It also forms sodium chloride and the metal as it reacts with different metallic halides. It has an atomic number of 11 and is represented in the Periodic table by the symbol Na.
Sodium boiling point- 882.940°C, 1621.292°F, 1156.090 K
In this article, will study physical properties of sodium and Chemical Properties Of Sodium Metal In detail.
Physical and Chemical Properties Sodium
Physical Property of Sodium Metal:
At normal temperature and pressure, sodium is a soft silvery metal that reacts with oxygen in the air to form greyish white sodium oxide unless it is contained in the oil or inert gas. Since it only has one electron in its valence layer, sodium metal is easily cut with a knife and is a strong conductor of electricity and heat. This results in poor metallic bonding and free electrons, which carry energy.
Sodium is the third least dense of all elemental metals, with a low atomic mass and a broad atomic radius, and is one of only three metals that can float on water, the other two being lithium and potassium. Sodium's melting (98 °C) and boiling (883) points are lower than lithium's but higher than the heavier alkali metals potassium, rubidium, and cesium, following periodic patterns down the group.
There are twenty different isotopes of sodium known, but only 23 Na is stable. By fusing two carbon atoms together in the carbon-burning process in stars, 23Na is produced; this requires temperatures above 600 mega-kelvins and a star with at least three solar masses.
Chemical Properties of Sodium Metal:
Sodium atoms have 11 electrons, one more than the noble gas neon's stable configuration. 495.8 kJ/mol and 4562 kJ/mol, respectively, are the first and second ionization energies. As a consequence, sodium is most commonly found in ionic compounds containing the Na+ cation.
1. Aqueous Solutions
Water-soluble sodium compounds contain halides, sulfates, nitrates, carboxylates, and carbonates. The aqua complexes [Na(H2O)n]+ are the most common aqueous species, with n = 4–8 and n = 6 shown by X-ray diffraction data and computer simulations.
Since sodium salts have a high affinity for water, direct precipitation of sodium salts from aqueous solutions is uncommon. Sodium bismuthate is an exception (NaBiO3). Sodium salts are normally separated as solids by evaporation or precipitation with an organic antisolvent, such as ethanol; for example, only 0.35 g/L of sodium chloride dissolves in ethanol.
2. Electrides and Sodides
Sodium, like the other alkali metals, dissolves in ammonia and some amines to form darkly colored solutions, which evaporate to leave a gleaming film of metallic sodium. The positive charge of the coordination complex (Na(NH3)6)+ is counterbalanced by electrons as anions in the solutions; cryptands allow the isolation of these complexes as crystalline solids. With crown ethers, cryptands, and other ligands, sodium forms complexes.
3. Intermetallic Compounds
Many metals, including potassium, calcium, iron, and the group 11 and 12 elements, form alloys with sodium. KNa2 and NaK are sodium and potassium compounds. At room temperature, NaK contains 40–90 percent potassium and is liquid. It functions well as a thermal and electrical conductor.
4. Salts and Oxides
Sodium compounds are extremely significant in the manufacturing of glass, paper, soap, and textiles, among other products.
The majority of soaps are fatty acid sodium salts. Sodium soaps have a higher melting temperature than potassium soaps (and seem "harder").
Sodium, like all alkali metals, reacts with water exothermically. Caustic soda (sodium hydroxide) and flammable hydrogen gas are produced in this reaction. As it is burned in the air, it produces mostly sodium peroxide and a small amount of sodium oxide.
Uses of Sodium
It's also used in soaps, molten metal purification, and sodium vapor lamps to improve the structure of some alloys.
Sodium is a part of sodium chloride, a vital compound in the living environment.
Sodium is essential for the production of organic compounds and the formation of esters.
Making glass necessitates the use of solid sodium carbonate.
Did You Know?
A strong connection exists between higher sodium intake and elevated blood pressure. According to studies, cutting sodium intake by 2 g a day lowers systolic blood pressure by two to four mm Hg. It is projected that lowering sodium intake by 9 to 17 percent will reduce hypertension cases by 9 to 17 percent. Every year, hypertension kills 7.6 million people prematurely around the world. (Salt contains about 39.3% sodium, with the remainder being chlorine and trace chemicals; hence, 2.3 g sodium equals about 5.9 g, or 5.3 ml, of salt—roughly one US teaspoon.)
FAQs on Sodium Properties
1. What are the key physical properties of sodium?
Sodium is a soft, silvery-white metal that can be easily cut with a knife. As a typical alkali metal, its key physical properties include:
- Low Density: It is lighter than water and will float on it.
- Lustrous: It has a bright, silvery lustre when freshly cut, but it tarnishes rapidly upon exposure to air.
- Malleability and Ductility: It can be hammered into sheets and drawn into wires.
- Conductivity: It is a good conductor of both heat and electricity.
- Low Melting Point: It has a low melting point (97.8°C) and boiling point (883°C) compared to most other metals.
2. What are the main chemical properties of sodium?
Sodium is defined by its high chemical reactivity. Its main chemical properties stem from its tendency to lose its single valence electron to form the Na⁺ ion. Important properties include:
- High Reactivity: It reacts vigorously with water, oxygen, and halogens.
- Strong Reducing Agent: It readily donates its outermost electron in chemical reactions.
- Formation of Basic Oxide: It burns in air to form sodium oxide (Na₂O) and sodium peroxide (Na₂O₂), which are basic in nature.
- Flame Test: Sodium and its compounds impart a characteristic golden-yellow colour to a Bunsen flame, an important test for its identification.
- Reaction with Water: It reacts with water to produce sodium hydroxide and hydrogen gas.
3. What are some important uses of sodium in daily life and industry?
Sodium and its compounds have several critical applications. Some important examples include:
- Sodium-Vapour Lamps: Used in street lighting due to their efficient, monochromatic yellow light.
- Nuclear Reactors: Liquid sodium is used as a coolant in fast breeder nuclear reactors because of its high thermal conductivity.
- Chemical Synthesis: It is a vital reagent in making compounds like sodium peroxide, sodium cyanide, and sodamide.
- Organic Chemistry: Used as a reducing agent in reactions like the Wurtz reaction for preparing hydrocarbons.
- Metallurgy: Used to extract less reactive metals like titanium from their chlorides.
4. Why is sodium metal so reactive and always stored under kerosene?
Sodium's high reactivity is a direct result of its atomic structure. It has a single electron in its outermost shell (valence electron) and a low ionisation enthalpy. This means very little energy is required to remove this electron, making it eager to react and form a stable positive ion (Na⁺). It reacts instantly and vigorously with air (oxygen and moisture) and explosively with water. To prevent these reactions, sodium is stored under an inert liquid like kerosene or paraffin oil, which protects it from contact with air and moisture.
5. What does sodium's position in the Periodic Table reveal about its properties?
Sodium is located in Group 1 and Period 3 of the Periodic Table. This position tells us a great deal about its behaviour:
- Group 1 (Alkali Metals): This signifies that it has one valence electron. This electron is easily lost, making sodium highly electropositive and reactive, with a fixed oxidation state of +1.
- Period 3: Being in the third period means it has three electron shells. Its large atomic size for its period contributes to its low ionisation energy, as the valence electron is far from the nucleus and weakly held.
Thus, its position predicts its metallic character, high reactivity, and tendency to form ionic compounds.
6. How does sodium react with water, and why is this reaction so vigorous?
When sodium metal is added to water, it reacts to form sodium hydroxide (NaOH), a strong base, and liberates hydrogen gas (H₂). The chemical equation is: 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g). The reaction is extremely vigorous because it is highly exothermic, meaning it releases a large amount of heat. This heat is often sufficient to melt the sodium metal (which darts across the water surface as a silvery ball) and can even ignite the hydrogen gas produced, resulting in a flame or a small explosion.
7. How do the properties of sodium differ from other alkali metals like lithium or potassium?
While sharing general group characteristics, sodium has distinct properties compared to its neighbours. When compared to lithium (above it), sodium is softer, has a lower melting point, and is more reactive. This is because sodium's larger atomic size means its valence electron is held less tightly. When compared to potassium (below it), sodium is harder, has a higher melting point, and is less reactive. Reactivity in alkali metals increases down the group. A key chemical difference is in its reaction with excess oxygen: sodium forms peroxide (Na₂O₂), whereas potassium forms superoxide (KO₂).
