Hack tech fact

Uses of interhalogen compounds- These are used as :  1- Fluorinated agents. For example , ClF³ and BrF³ are used in making UF6 which is useful in making U²³5 used as a fuel in atomic reactor. 2- as a non aqueous solvents. 3- A solution of ICl glacier acid is used for determination of iodine number which is used to measure the unsaturation of oils and fats. 4- ICl is used as a catalyst in oxidising As²O³ by Ce(SO⁴)². 5- as a oxidiser for propellants.

Properties of inter halogen compounds- 1- They are generally covalent compounds. 2- Their melting point and boiling point increase with the increase in the difference of electronegative. 3- They are more reactive than the Constituent halogens. It is because, the bond between two dissimilar electronegative elements is weaker than two similar electronegative elements. 4- They are good oxidising agents. 5- Chlorofluoro hydrocarbons are known as Freons which are used as a  refrigerants. 6- Thermal stability decrease as the electio ngative difference between two halogen atom decrease. For example ,ClF is more stable than IBr.

Uses of fluorine:- Some of the important uses of fluorine are as :  1- For the preparation of fluorine compound  2- For the preparation of Freons which are used as refrigerants. 3- For the preparation of a polymer, i.e., Teflon (-CF²-CF²-)n which is used as a resistant to acids, oxidising agent and alkalies. 4- As an oxidising agent in rocket. 5- Due to high dielectric constant and insulting properties, sulphur hexafluoride is used in X-ray and high voltage machines. 6- Cryolite and fluorspar (CaF²) are used in the extraction of aluminum. 7- NaF and Na³AlF6 (Cryolite) are used as insecticide. 8- CuF² is used in the ceramic industry and as a flux soldering. 9- D.D.F.T which is similar to D.D.T. is extensively used as an active fungicide and fumigant.

P - Block Elements  Group 17 elements -    The non-metallic elements Chlorine, fluorine, bromine, iodine and astatine constitute group VIIA or 17 of the periodic table. These are collectively known as Halogens as their salts are present in sea water (Greek:halo = sea salt, genes = producing). They have one electron less than the nearest noble gas elements, for which they exist as non-metals. These are highly electronegative elements and thus are very reactive in nature. Fluorine, the first number of the element is the most reactive element because of its highest electronegativity value. Astatine the last member of halogen family is a radioactive element which has very short life period.

Physical properties of Chlorine:-  1- It is greenish yellow gas with a pungent irritating odour. 2- It is poisonous, it produces headache and large quantities taken prove fatal.. 3- It is 2.5 times heavier than air. 4- It is soluble in water and the solution is known as Chlorine water. On cooling at 0°C it forms chlorine hydrates (Cl².8H²O)  5- It boils at _34.6°C.

Chlorine (Cl²)-  Chlorine is a reactive non- metal and found mostly in the combined state as chlorides combined state as chlorides. It was discovered by Scheels in 1744 by heating HCl with MnO². Davy established it's elementary nature in the year 1810 and name chlorine in the besic of it's colour (Greek,chloros =greanis yellow). The most commonly found chloride is sodium chloride which occur in sea water, lakes and in the rocks.

Uses of HF : It is used:  1- In the etching of glass and making marks on glass instruments. 2- In the manufacturer of fluorine. 3- In the preparation of artificial cryolite which is highly used in metallurgy of aluminum. 4- In the manufacturer of fluorine containing dyes which finds extensive resistance to light. 5- In the manufacturer of the polymers like Teflon which have high thermal resistance and are inert to acids and alkalies. 6- For removing sand from iron and from artificial graphite's. 7- For the preparation of Uranium hexafluoride b(UF6), which is employed for the separation of Uranium isotopes by the gaseous diffusion process. 8- For preparing alkali metal fluorides which is used as mordant dyeing industry .  9- For the preparation of Freons which is used as a refrigerant in many of the cooling processes. 10- In the pickling of alloy steels.

 Uses of Cl² - It is used : 1- as a bleaching agent. 2- in the sterilization of drinking water. 3- in the manufacturer of the bleaching powder, DDT, chloroform, carbon tetrachloride , hydrochloric acids, chlorates and a large number of synthetic organic compounds. 4- as germicides and disinfectants. 5- in the extraction of gold and platinum. 6- in the manufacturer of poisonous gases phosgene (COCl²) , tear gas (CCl³ NO²) and mustard gas (ClC²H⁴ - S - C²H⁴Cl)  7- in the preparation of antiseptic solution (NaOCl). 8- in the manufacturer of the solvent like westron. 

Physical properties of Hydrogen iodide (HI) - 1- It is a colourless gas having pungent odour. 2- It is heavier than air and fumes strongly in moist air. 3- It condenses to a colourless liquid at 0°C and 4 atmospheric pressure. 4- It is highly soluble in water. 5- It boils at - 35.5°C and freezes to a white solid which melts at - 50.8°C. 6- It forms a constant boiling mixture at 127°C when the solution contains 57% of HI.

Physical properties of HBR- 1-  It is colorless purgent smelling gas. 2-  It's highly soluble in water and fumes in moist air. 3- It is heavier than air. 4- It  forms constant boiling mixture at 126°C when it contains 48% of the gas in solution. 5- It condenses to a liquid at - 67°C and solidifies at - 88.5°C.

Uses of HCL: It is used - 1-  in the preparation of chlorine, metal chlorides, aquaregia etc. 2- in cleaning the metal  3- in pharmaceutical industries. 4- for extracting glue from animals tissues and bones. 5- as a laboratory reagent. 6- in the manufacturer of dyestuffs and in sugar industry.

 Difference between HF and other hydra acids of Halogens: 1-  It is associated with through the H-bonding and hence it is a liquid while other halogen acids are gases. 2-  Due to H-bonding it's viscosity and boiling points are higher than other halogen acids. 3-  It has high corrosive action on skin. 4-  It is very weak acid and extremely stable as compared to other halogen acids. 5-  It is not oxidised by strong oxidising agents while others are oxidised. 6-  It attacks glass forming SiF⁴ and hydrofluosilic acid while other don't attack glass. 7-  It is unique in forming salts contains HF² anion. 8- It doesn't give ppt with AgNO³ because AgF is soluble in water while others give ppt with AgNO³

Why halogen molecules exhibit different colors?. _-> All the halogen molecules are coloured. Because they absorb light in the visible region which causes excitation of outer electron to higher energy levels. The excitation energy. Therefore, fluorine  absorb violet (high energy) portion of the visible light and thus appears yellow. On this ground, it may be explained that Cl² is greenish yellow and bromine is red.

Liquefication of noble gasses : Due to to weak intermolecular Ven der waals forces of attraction these gases possess very low melting points and boiling points. However, the melting point and boiling point of these gasses increase down the group from He to Rn which is due to increase in the size of the atoms. 

Ionisation energy: The Ionisation energies of this elements are the highest in their respective periods due their stable electronic configuration. However, the Ionisation energies of the elements decrease on moving  down the group from He to Rn, which is due to the increase in the atomic size and screening effect.

Enthalpy of fusion and enthalpy of vaporisation- The enthalpy of fusion and enthalpy of vaporisation of noble gases are very low . It's due to the presence of the of weak van der waals forces of attraction among the molecules of noble gases. However, the values of these properties increase from He to Rn which may be due to the increase in the magnitude of inter- atomic forces.

Atomic Radii of Nobel Gasses : In case of the noble gases, the atomic radii are expressed in terms of their van der waals radii. The other elements are expressed in terms of there co-valent radii. Therefore, the atomic radii of the inert gas elements are quite large in comparison with the other elements in their respective period.The atomic radii increase on moving down the group from He to Rn which is due to addition of the new shells and increase in screening effect.

Solubility of noble gasses:  These are slightly soluble in water and the solubility increases from He to Rn. As the size of the noble gases increase with increase in their atomic numbers, the extent of dipole - induced dipole interaction between the Nobel gas molecules and water molecules increases. (What is a polar molecules and induces dipole in noble gasses by distorting their electron cloud) . Thus, solubility in water increases.   

 Isolation of Nobel Gasses: 1-                      Helium-   Helium is commercially obtained from natural gasses by compression and cooling method. The natural gas mainly contain hydrocarbons along with H2S, CO2, H2 O, N2 and He. The natural gas is compressed to about 100 atm and cooled to about -200°C. Under these conditions, other gases liquefy leaving Helium. Then He is collected and purified to get pure helium. 2-  Neon, Argon, Krypton and      Xenon-  These gasses are obtained by the Fractional distillation of liquid charcoal at different temperatures. 3-              Radon-   Radon is obtained during the radioactive disintegration 

About Group 18 Elements: Zero group (group-18) of the periodic table constitutes Helium (He), Neon (Ne) Argon (Ar), Krypton (Kr), Xenon (Xe) and Radon (Rn). These are all monoatomic gas. Because of there chemical inertness they are also known as inert gasses and have been placed in a separate group in the periodic table called Zero group. Except radon, all other gasses are present in the atmosphere in very small quantities. Thus, they are known as rare gases or arogens.  Now-a-days, several compounds of Kr and Xe have been prepared. Therefore, inert gases are now called Nobel gasses as they show reactivity to some extent.  

Uses of Helium  :-  1- It is used as a coolant in gas cooled atomic reactor. 2- As it is a lighter gas, it diffuses more rapidly and thus helium oxygen mixture is used for asthma of treatment. 3- It is used for filling balloons and air ships as it is light and non - inflammable gas . 4- It is used to provide inert atmosphere in the welding and melting of certain metals which are easily oxidised. 5- Because of it's inertness and high I.E. it used for filling electrical transformers , vacuum tubes and radio tubes etc. 6- It is used in the preservation of food, as it maintain inert atmosphere around foods and are not destroyed by bacterial actions. 7- Liquid helium has very low temperature and hence is used in the research work where low temperature is required. 8- It is suitable for low temperature gas thermometry because this this has low b.pt and has nearly ideal gas behavior. 9- A mixture of He and O² is used for respiration in place of air sea divers. It is because the nitrogen o

Discovery of Neon, Krypton and Xenon: Ramsay and Traverse suspected that the argon obtained from air was not a single gas but was a mixture of several other inert gases. He subjected the liquid argon obtained from air to Fractional distillation and to there surprise they found the presence of other inert gases . The first fraction was named neon (Greek : neos =new).The rest fractions reported were Krypton (Greek: Krypton=hidden) and Xenon (Greek : Xenon = stranger). 

 Uses of Krypton:  1- It is also used for filling incandescent metal filament electric bulbs. 2- It is used to a small extent in discharge tube. 3- Kr-85 is used in electronic tubes for regulating voltage and for testing of leaks. 4- it is used in place of argon in high efficiency miner's cap lamp.   Uses of Radon : 1- Being radioactive in nature it is used in the treatment of cancer. 2- It is used in radioactive research .

Uses of Xenon : 1- It is used in photographic flash tubes for quick photography.   2- Liquid xenon is used in bubble chamber to detect x photons and neutral mesons. 3- A mixture of Xe and other inert gases when filled in electric lamp produces light of different colors. Uses of Radon: 1- Being radioactive in nature , it is used in the treatment for Cancer and other disease , This treatment is known as (radiotherapy). 2- It is used in radioactive research work.

Uses of Argon: 1- Mixture of Argon and nitrogen is used for filling electric bulb and tubes. 2- It is used for providing inert atmosphere for welding of easily oxidation metals. 3- It is used for filling florescent tube and radio valves . 4- Mixture of Ne and Ar Mixture is used to get light of various colors necessary for advertisements. 5- Mixture of Ar and Hg vaupours are used in discharge tubes to produced a glow of blue colour.   

Uses of Neon: 1- Neon is extensively used in neon  glow lamps for advertising . It is because neon has a characteristics of properties giving an orange red glow in a discharge tube at 2mm pressure and at 1000 volt. This light become visible from the distance even thought fog and mist . 2- Since neon lights have better penetrating power through the fog and mist , these are used in the beacon lights for the safety of air navigation. 3- Neon mixed with argon or mercury vapours produced different coloured light in different types of light of glasses . These are used in advertisement and in sign boards Example:  Gas mixture - Type of Glass                              Tube 1- Neon                    1- colourless 2- Neon-argon               2- colourless 3- Ne-Ar-Hg vapours    3- purple    Color of the light produced                 1- Orange red                                   2- Ripple effect                             3- Dark blue 4- Mixture of He and Ne does not conduct electricity u

Metallic character:  Transition elements can lose one or two (ns¹  or ns²) electrons and are changed to positive cations. Hence, they are metals. They are solid ( except Hg which is a liquid at room temperature), hard, lustrous, malleable , ductile and good conductor of heat as well as electricity and they possess high tensile power or strength.     This is due to the fact that transition metal atom have one or two electron in their outermost shell (ns¹-²), and their ionization enthalpies are relatively low , for which they can form metallic bond. The unpaired d - electrons also cause the Formation of metallic bonds . It is a fact that greater the number of unpaired d-electron , stronger is the metallic bonding due to the overlap of unpaired electron between different atoms . Since Cr , Mo and W have maximum number of unpaired d-electron (=5) , they are hard metals ; Zn , Cd and Hg are soft metals having low melting point because of having no unpaired d-electron. Hg is a liquid due to

Paramagnetism : A paramagnetic substance is attracted by the magnet .  Paramagnetism is associated with the presence of the unpaired electron in the atoms , ions, or molecules . Since the paramagnetic properties is due to the presence of unpaired electron in the (n-1)d or (n-2) f - orbitals, only those atoms or ions having unpaired electron show  paramagnetism. The greater the numbers of unpaired electron in a species (ions or atoms), the more strongly paramagnetism it is .            Thus , Cu+ (3d ¹0 4s0) and  Cu²+(3d94s0) are diamagnetic (not magmatic) and para magmatic , respectively , because they contain zero and one unpaired electron respectively . Similarly, Fe ²+ (3d6 4s0) and fe³+ (3d5 4s0) having respectively 4and5 unpaired electrons are both parameters . However , Fe 3+ is more strongly paramagnetic than Fe2+    The catalytic power is probably due to the use of (n-1) d - orbitals or due to the Formation of some interestital compound which absorb and activate the reacting su

Catalytic properties    of Transition Element- :- some of the transition metals and their salts act as catalyst . For example, finely divided iron act as a catalyst in Haber's process for the manufacturer of ammonia. Finely divided nickel is used as a catalyst in the hydrogenation of oil to fat in the manufacturer of vegetable ghee . Decompression of bleaching powder solution is catalysed by Cobalt salt . MnO² is used as a catalyst in the decompression of H²O² solution in contact process .    The catalytic power is probably due to the use of (n_1) d-orbitals or due to the Formation of some interestital compound which absorb and activate the reacting substance.

Ionic radii : The values of ionic radii of Ti²+ to Cu²+  are given below :  Element - Ti - V - Cr - Mn - Fe  r(M²+)(pm) - 90-88-84-80-76 The ionic radii decrease in a series due to progressive increase in the effective nuclear charge. Since the effective nuclear charge in M³+ ion is greater than the in M²+ ion, the ionic radii of transition elements decrease with increase in oxidation state, and vice versa. However , the ionic radii of transition elements are smaller than that of s-and p-block elements belonging to the same period.

Formation of                Interstitial  Compounds: Transition of metal form a number of interstitial compounds with small - sized atoms like H,C,N,B etc . Steel is an Interstitial compounds in which empty spaces among iron atoms are occupied by carbon atoms . Because of the interstitial compounds formation, the transition metals become more hard and rigid and their properties are modified.