p-Block Elements

Boron is a non metal belonging to the p block. Being a non metal it is a poor conductor of electricity at room temperature but a good conductor at high temperature. The element is not found free in nature, but occurs as orthoboric acid which is usually found in certain volcanic spring water and as borates in boron and colemantie.

An oxide that combines with water to give an acid is termed as an acidic oxide. Acidic oxides are the oxides of non-metals. Since boron is a non metal, it forms acidic oxide. Boron oxide(B₂O₃) is acidic and reacts with water to reform boric acid. When combined with water, acidic oxides produce acids. Acidic oxides are, therefore, known as acid anhydrides, e.g., sulphur dioxide is sulphurous anhydride; sulphur trioxide is sulphuric anhydride.

It is a member of group IV A. 

The valency of the elements is not a periodic property. It is  the combining power of an element. International Union of Pure and Applied Chemistry called it as: The maximum number of univalent atoms, that may combine with an atom of the element under consideration, or with a fragment, or for which an atom of this element can be substituted. So, valency of all the element is basically how many electrons an element can donate or an element can accept to form an ionic bond.

The noble gases, including helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn)  are considered  as inert .These elements are unreactive because they are very stable in their naturally occurring forms. Neon has eight electrons in its outermost level and is stable so it is chemically inert & does not form any compound.
 

The process of producing pure alumina from bauxite is known as Bayer's process - extraction, precipitation and calcination. The aluminium-bearing minerals in bauxite are selectively extracted from the insoluble components (mostly oxides) by dissolving them in a solution of sodium hydroxide (caustic soda).

A flashbulb is made up of a base, either metal or glass, a glass envelope usually coated on the interior and exterior with a plastic safety coating, primer paste, a tungsten igniter filament, a filling of shredded aluminum or other alloys with aluminum and oxygen. It fires when a voltage of 3-30V is applied to the ignition filament.

It is an alloy of aluminum that contains copper, manganese, magnesium, iron, and silicon and is resistant to corrosion by acids and sea water.Duralumin alloys are relatively soft, ductile, and workable in the normal state; they may be rolled, forged, extruded, or drawn into a variety of shapes and products. Their light weight and consequent high strength per unit weight compared to steel suit them for aircraft construction.

Diamond is the hardest substance found in nature, but few people realize that Diamond is four times harder than the next hardest natural mineral, corundum (sapphire and ruby). But even as hard as it is, it is not impervious. Diamond has four directions of cleavage, meaning that if it receives a sharp blow in one of these directions it will cleave, or split.Diamond conducts heat better than anything - five times better than the second best element, Silver.

Thermite  welding is process in which fusion is produced by heating with superheated liquid metal and slag resulting from a chemical reaction between a metal oxide and aluminum, with or without the application of pressure. Filler metal, when used, is obtained from the liquid metal.The Thermite Process or Goldschmidt Process is the method of obtaining liquid metal by reduction of the oxide with aluminium powder, when ignited with magnesium ribbon it reacts by producing iron and aluminium oxide at an intensely high temperature approaching 3000 degrees Celsius.It was developed for making welding repairs in situ, such as rail tracks. It was adopted by the army for use in incendiary bombs.

The Dutch process (or stack process) was formerly the principal method by which white lead was prepared. It consisted building a stack of earthenware pots containing acetic acid upon a thick layer of spent  tanor manure and placing strips or coils of metallic lead over the pots; boards were then laid to form a false floor over the whole and more stacks built on top. The structure was then sealed and over time the metallic lead converted into lead carbonate corrosion caused by the action of the acetic acid vapour in the presence of carbon dioxide.

The elements of  Group 7  are known as halogens. The term halogen means salt-former and compounds containing halogens are called salts. The halogens exist, at room temperature, in all three states of matter - Gases such as Fluorine & Chlorine, Solids such as Iodine and Astatine and Liquid as in Bromine. The Halogen elements on the Periodic Table are: Fluorine, Chlorine, Bromine, Iodine, Astatine.

The production of aluminium by Hall's process was one of the earliest applications of electrolysis on a large scale, and is still the major method for obtaining that very useful metal. The process was discovered in 1886 by Charles M. Hall. Aluminium  is very reactive and therefore difficult to reduce from its compounds by chemical means. On the other hand, electrolysis of a molten aluminium salt or oxide is difficult because the salts are hard to obtain in anhydrous (dry) form and the oxide, Al₂O₃, does not melt until 3,762°F (2,072°C). Hall discovered that Al₂O₃, in the form of the mineral bauxite, dissolves in another aluminium mineral called cryolite, Na₃AlF₆, and that the resulting mixture could be melted fairly easily. When an electric current is passed through this molten mixture, the aluminium ions migrate to the cathode, where they are reduced to metal. At the anode, oxide ions are oxidised to oxygen gas.

The existence of elements in two or more different forms is called allotropy & nthe different forms are called allotropes. In the case of oxygen, there are two forms: 'normal' dioxygen (O₂) and ozone, or trioxygen (O₃). These two allotropes have different molecular configurations. More commonly, allotropy occurs because of different crystal structures in the solid, and is particularly prevalent in groups 14, 15, and 16 of the periodic table. In some cases, the allotropes are stable over a temperature range, with a definite transition point at which one changes into the other. For instance, tin has two allotropes: white (metallic) tin stable above 13.2°C and grey (nonmetallic) tin stable below 13.2°C. This form of allotropy is called enantiotropy.Carbon also has two allotropes - diamond and graphite - although graphite is the stable form at all temperatures. This form of allotropy, in which there is no transition temperature at which the two are in equilibrium, is called monotropy.

In Ostwald's  process, Ammonia is converted to nitric acid in two stages. It is oxidized by heating with oxygen in the presence of a catalyst of platinum with 10% rhodium, to form nitric oxide and water. This step is stongly exothermic, making it a useful heat source once initiated (delta H = -950 kJ).

It is obtained by burning natural gas in the presence of limited supply of air and collecting the soot on the underside of a revolving disc which is scrapped off and packed. It is not an allotropic forms of coal.

Disinfectants sterilize surfaces, medical equipment and other man-made objects. Chlorine is  used to disinfect swimming pools, and is added in small quantities to  drinking water  to reduce waterborne diseases.

It is prepared by the destructive distillation of bones of animals. Bones obtained from slaughter houses, are first treated with certain bacteria to remove all the fleshy remnants. Then the bones are taken in a furnace and heated strongly in the absence of air. The solid matter obtained contains nearly 10% of carbon, and almost 90% of calcium phosphate. It is then treated with dilute hydrochloric acid, which dissolves the calcium phosphate, leaving behind bone charcoal. This can be separated by filtration.Bone charcoal is a black powder called as 'ivory black'. It is porous and can adsorb colouring matter. It is mostly used in sugar industry to decolourise sugar.

Graphite usually occurs in flakes in metamorphosed rocks rich in carbon, but it can also be found in veins and in pegmatites. Where large deposits are found it is mined and used as an industrial lubricant and for 'lead' in pencils. Graphite is a polymorph of the element carbon. , Graphite is a good conductor of electricity.,a very good lubricant,opaque, and  crystallizes in the hexagonal system.Somewhat of a surprise is that at surface temperatures and pressures, Graphite is the stable form of carbon. Graphite has a sheet -like structure where the atoms all lie in a plane and are only weakly bonded to the graphite sheets above and below. It may seem strange that one of the softest minerals and also a very slippery lubricant is the high-strength component in composites used to build automobiles, aircraft, and of course golf club shafts. It is also used as a moderator in nuclear reactor.

Aqua Regia is a highly corrosive fuming liquid which contains hydrochloric acid and nitric acid in the ratio of 3:1. It can dissolve even gold, platinum and other noble metas too.

Hydrogen sulfide is slightly heavier than air; a mixture of H₂S and air is explosive.Hydrogen sulfide acts as a reducing agent.Hydrogen sulfide is slightly soluble in water and acts as a weak acid, giving the hydrosulfide ion HS− and the sulphide ion S2−.A solution of hydrogen sulfide in water is initially clear but over time turns cloudy. This is due to the slow reaction of hydrogen sulfide with the oxygen dissolved in water, yielding elemental sulfur, which precipitates out.

Magnetite is a natural magnet, hence the name, giving it a very nice distinguishing characteristic.  Magnetite is a member of the spinel group which has the standard formula A(B)₂O₄. The A and B represent usually different metal ions that occupy specific sites in the crystal structure. In the case of magnetite, Fe₃O₄, the A metal is Fe ⁺² and the B metal is Fe ⁺³; two different metal ions in two specific sites. This arrangement causes a transfer of electrons between the different irons in a structured path or vector. This electric vector generates the magnetic field.It is an ore of iron & it does not contain aluminium.

Because of extremely small size of its atom and high electronegativity, boron differs in its properties from other elements of the group. On the other hand, it resembles silicon to some extent due to diagonal relationship.. Boron and silicon exhibit the typical properties of non-metals. These do not form cations. Both exist in amorphous as well as crystalline forms. Boron oxide (B₂O₃) and silica (SiO₂) both are acidic and dissolve in alkali solutions to form borates and silicates respectively.

Oxygen, sulphur, selenium, tellurium and polonium constitute the group 16 of the periodic table of elements. The first four elements are collectively called CHALCOGENS. The name derives from the Greek word for bronze and points to the association of sulphur and its congeners with copper. All these are non-metallic in character. The metallic character increases down the group. The last element of the family, polonium has metallic character and is a radioactive element with a very short life period.