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 What are rare earth elements?

What are rare earth metals used for?

What is borax?

Structure of Borax

Electrolytes are the substance in electrochemistry which dissolved in water and dissociate cations and anions during the electrolysis. Acids, bases, and salts in the state of solution or fused state conduct electricity by the transfer of electrons are called electrolytes. The decomposition of electrolytes due to the passage of electricity is called electrolysis. The current usually enter or leaves the electrolytes through some rods or strips of metal is called an electrode.

Strong electrolyte examples

The extent or degree of dissociation of different electrolytes is different. Strong electrolytes dissociate completely and render the solution in water highly conducting are called strong electrolytes. All salts, mineral acids like sulfuric acid (H₂SO₄), nitric acid (HNO₃), hydrochloric acid (HCl), and bases like sodium hydroxide (NaOH) and potassium hydroxide (KOH) dissociate practically in water solution are called strong electrolytes. The conductance of such acids and bases is very high and called strong acids and bases.

Weak Electrolytes Examples

On other hand, there are many substances that dissociate only to a small extent in water solution. The solution of such electrolytes has very low conductance properties or power. Such substances are called weak electrolytes. The carboxylic acids, phenols, alcohols, and some inorganic acids like hydrocyanic acid (HCN), boric acid (H₃BO₃), and bases like ammonia (NH₃), amines are examples of weak electrolytes.

Electrical conductivity of solvents

This idea about strong and weak electrolytes is quantitative only. There are some electrolytes, such as trichloroacetic acid solution are exhibiting intermediate behavior. In deciding the nature of strong and weak electrolytes, we consider water solution as a solvent. It must be remembered that the nature of solvent plays an important role in the degree of dissociation of dissolved substances. Generally, the higher the dielectric constant of the solvent, the greater is the chance of dissociation. Besides the dielectric constant of the solvent, there are other factors like hydrogen bonding that play an important role to describe electrolytes.

Group-14 elements (IVB) in the periodic table include carbon (C), silicon (Si), germanium, tin (Sn), and lead (Pb) with the atomic number 6, 14, 32, 50, 82. The first two elements in the carbon family occupy a special position in our life. Carbon is the key chemical element of all living organisms forms a large number of organic and inorganic compounds. Silicon is the second most abundant element after oxygen in the earth's crust. Silicon compounds like stones, sands, and clays are the principal building materials in our civilization.

Properties of Group-14 Elements

The chemistry of the group 14 elements follows from their electronic configuration although the references in properties between carbon and silicon are rather wide.

The metallic character of group 14 elements increasing with the increasing atomic number. Therefore, carbon and silicon are typically nonmetals but the metallic properties increasing from germanium to lead. The sum of four ionization energy is exorbitantly high and cannot form an M⁺⁴ cation. Therefore, in most cases, the elements attaining noble gas configuration by forming four single covalent bonding with sp³ hybridization. The formation of multiple chemical bonding decreases from carbon to silicon atom.

The group-14 elements, carbon has several types of allotropic forms, only diamond and graphite are common among them. The four other rare and poorly understood forms are beta-graphite, Lonsdsdaleite, or hexagonal diamond, chaoite, and carbon-VI. Silicon and germanium diamonds type cubic crystal lattice with Si-Si bond distance 235 pm. Tin has two allotropic forms like alpha-tin and beta-tin but lead exists only in a cubic closed paced metallic crystal lattice with a density of 11.34 g cm^-3.

Group-16 elements or Group-VIB contains chemical elements like oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium with the atomic number 8, 16, 34, 52, 84. Oxygen is the most abundant element and makes up to 47 percent of the earth's crust in the form of oxides and oxoacids. It supports the respiration of the animal body and essential for human life. Sulfur occurs in the native state and metal sulfides like pyrites (FeS₂), galena (PbS), zinc blended (ZnS), and metal sulfate like gypsum (CaSO₄, 2H₂O). It makes up to 0.04 to 0.03 percent of the earth's crust. Selenium and tellurium contain fewer quantities in sulfide ores. Polonium was discovered by scientist Curies from the radioactive materials pitchblende in 1898. It also from the radioactive decay of radium.

Properties of Group-16 Elements

The elements of group 16 are collectively called chalcogen from their natural association with copper (chalcos). Oxygen has two allotopic forms like dioxygen (O₂) and ozone (O₃). Ozone is formed in the upper atmosphere by the action of solar UV radiation on oxygen. The ozone layers protect the earth from harmful electromagnetic radiation coming from the sun. Nitrogen oxide and chlorofluorocarbons destroy the ozone layers. The element sulfur forms a large number of allotropes containing puckered rings with 6 to 20 atoms or chains. Common rhombic and liquid sulfur contains an S₈ ring with a melting point of 115°C. The trend in various properties among the group members parallels those observed in previous groups. The first member of Group-16 like the oxygen has a strong tendency to form a chemical bond or pi-bond with p-p orbitals and a strong hydrogen bonding.

Nitrogen in Periodic Table Elements

Nitrogen atomic number 7 and symbol N is the chemical element of Group 15 of the periodic table occurs as the diatomic gas dinitrogen N₂ with no allotropic forms. The elements of this group like nitrogen, phosphorus, arsenic, antimony, and bismuth are collectively called pnictogen or pnicogen from the greek word choking. The element nitrogen and phosphorus are essential constituents of the living system used mainly for the manufacturing of fertilizer. The heavier member of the group, particularly arsenic is extremely toxic and causes water pollution.

Chemistry of Nitrogen

The chemistry of the element is very interesting. The remarkable tendency of catenation is observed in carbon and practically disappears in nitrogen. The importance of p-p pi-bonding increases with the increasing electronegativity of the atom. The electronic configuration of nitrogen is 3s² 3p³ with two paired electrons in the s-orbital and one unpaired electron in three p-orbitals. The electronic configuration suggests that nitrogen is closer to the next noble gas neon than the presiding noble gas helium. If we assuming the +5 cationic configuration by losing all the five outer electrons is just impossible. A huge amount of energy is required for this purpose. The sum of five ionization energy cannot be compensated by the gain of lattice energy by ionic bonding. Therefore nitrogen formed chemical compounds in +5 oxidation states are covalent compounds. The first ionization energy fall from nitrogen to bismuth is slow but metallic character along with the group steadily increases.

Nitrogen halides are restricted up to only the trihalides but phosphorus has pentahalides in addition to the trihalides due to the presence of vacant d-orbital in phosphorus atom. The d-orbitals of phosphorus can utilize to form pentavalent trigonal bipyramidal PCl₅ with sp³d hybridization.

Uses

Nitrogen is the essential chemical constituent of plants and animals used widely to provide an inert atmosphere in metallurgy and in various chemical industries like the iron and steel industry or petrochemical industry. Liquid nitrogen is used as a refrigerant in low-temperature matching and grinding rubber or rubber-like substance, preservation of biological specimens.

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