Explanation
Mercury (I) is a dimer consisting of mercury (II) ion and a neutral mercury atom. There are no individual mercury (I) ions. This is why there is no HgCl, only Hg2Cl2. It is said that mercury (I) (Hg22+) disproportionate to form mercury (II) and mercury metal, as if this were a redox reaction and the mercury was changing oxidation state. (Similar to the disproportionation of Cu (I) to form Cu and Cu (II).) But instead of a redox reaction to make Hg and Hg (II) from Hg22+, it simply decomposes. There is no electron transfer, because the Hg22+ ion exists as at atom of mercury bonded to a Hg22+ ion, as in Hg- Hg22+. There are many examples of the decomposition of mercury (I) compounds to form mercury (II) compounds and metallic mercury. The classic example is in the Group One qualitative analysis test for mercury, where NH3 is added to Hg2Cl2 and it forms mercury metal and HgNH2Cl, where Hg is +2.
SinCl, CuCl2, CuF2, CuBr2 are stable and they exist but CuI2 not, because Iodiode ions are strong reducing agents, Therefore copper (II) Iodide reduces to insoluble coper (I) iodide. Thus making CuI2, CuI. CuI is not stable, so it does not exist in solution. It is not stable because of the solubility.
Minamata disease, some times referred to as chisso-Minamata disease , is a neurological syndrome caused by severe mercury poisoning . Symptoms include ataxia, numbers in the hands and feet, general muscle weakness, narrowing of the field of vision and damage to hearing and speech.
Usually the color of transition metal compound is due to d-d transition. When the d-level is not completely filled , it is possible to promote electron from a lower energy d-orbital to higher energy d-orbital by absorption of a photon of electromagnetic radiation having an appropriate energy.
Hence on the otherhand we can say that the color of tranistion metal is due to imcomplete (n-1) d- subshell.
Paramagnetism is exhibited due to the presence of unpaired electrons in the species.
A "transition metals" are any elements in the d-block of the periodic table, which includes groups 3 to 12 on the periodic table. Hence silver, gold, platinum, iron, copper and titanium are part of the transition metals.
The d-block elements being smaller in size and have high electropositive density and they consists of (n-1)d free orbitals to accepts the free electrons from the ligand and it forms complexes easily.
Transition elements exhibit variable valency to form intermediate compounds. Hence they act as a good catalyst. The catalytic activity of the transition metals and their compounds is described to their ability to adopt multiple oxidation states and their complexing ability.
If a solution absorbs a part of visible range of the spectrum which is transmitted, eg., a copper sulphate solution absorbs light at the red end of the spectrum and is blue in color. Comparision of colored solutions with a series of similar solutions containing known concentration of the colored compound permits eleimination of the concentration of the substance responsible for the color.
There are also many ways to make rain in a cold cloud, but the most common way is to use dry ice or silver ioxide. This is mainly because the temperature of dry ice is – 780C spreading dry ice in a cold cloud lacking ice crystals will rapidly transform supercooled water into ice crystals, which will eventually became rain without the help of ice-crystals nuclei. Silver ioxide on the otherhand, is a very effective ice – crystal nucleuis, so it act as an ice crystal nuclecus, can facilitate the solification of water drops below -50C into ice crystals.
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