Sky Of Chemistry

There are different ways of classifying them  1 st classification: Depending upon whether the polymer contains the atoms of only one element or of different elements in its backbone, they are classified into the following two groups. [1] Homo-atomic polymers: These polymers contain the atoms of only one element in their backbones Silicon, phosphorus, sulphur, germanium and tin from homo-atomic inorganic polymer. For example, sulphur has a tendency to form chains or rings in its elemental form (S 8 ) and in several compounds, like persulphides (H-S-S-H, H-S-S-S-H, H-S-S-S-S-H etc.) [2] Hetero-atomic Polymers: These contain the atoms of different elements in their backbones 2 nd Classification Inorganic polymers can also be classified in another way, which is base on the type of reaction by which the polymers are formed. On this basis, inorganic polymers may be of the following types: [1] Condensation (polymerisation) polymers. Condensation polymers are those, which are formed by t...

All the covalent macromolecules, which do not have carbon in their back bones are considered to be inorganic polymers. Inorganic polymers  are  polymers  with a skeletal structure that does not include carbon atoms in the backbone. ... The term  inorganic polymer  refers generally to one-dimensional  polymers , rather than to heavily crosslinked materials such as silicate minerals. Example : Crystals (e.g. oxides and halides), condensed. These polymers posses distinctive physicochemical characteristics and unique physical, mechanical and electrical properties. These polymers are of extensive utility in everyday life, particularly in the area of engineering and technology.

The word " organic " was introduced by Berzelius in 1780 to introduce chemicals which were obtained from living sources. Organic chemistry has long been regarded as a separate and unique branch of chemistry, organic chemistry is the body of knowledge which is concerned with the physical and chemical properties of the broad group of carbon compounds containing hydrogen and one or more additional elements like oxygen, nitrogen, sulphur  etc. However, compounds of carbon containing only carbon and oxygen like CO, CO 2 , CO 3 -2 are not studied under organic chemistry. Similarly, compounds containing carbon and nitrogen are not considered to be organic compounds. To understand organic chemistry, knowledge of valency of atoms is essential. Valency of different atoms: Atom              Valency   H                      1  O                  ...

Fluorescence  When a beam of light is incident on certain substances, they emit visible light or on radiations and they stop emitting light or radiations and they stop emitting light or radiation as soon as the incident light is cut off. This phenomenon is known as fluorescence . The substance that exhibit fluorescence are known as fluorescent substances. When a substance absorbs light energy, electrons move from inner orbits to outer orbits. When these excited electrons return to the ground state, the light is emitted. This emitted light may possess a different frequency than the incident light. X (Normal state) + hv (Photon) ⟶ X* (Excited state) X* ⟶ X** + hv' X** ⟶ X + hv" Where X** represents an energy state between X and X*. The emitted radiation frequencies v' And v" are different from v, the frequency of incident radiation. Some Characteristics of fluorescence: (i) This phenomenon is instantaneous and starts immediately after the absorption of light and stops ...

Luminescence Usually, light is obtained by heating solids or solid particles to high temperatures. By heating a tungsten(W), platinum wire or carbon filament electrically or in a flame, bright light can be obtained. The phenomenon in which thermal energy is converted into the light is known as 'incandescence'. When the emission of visible radiation occurs due to some cause other than temperature, the phenomenon is known as 'Luminescence'. Light is produced at low temperatures, so it is also known as cold light. In both incandescence and luminescence, light is emitted due to the return of electrons from the exciting position to a lesser excitation position or ground state.  Classification of Luminescence 1. Photoluminenscence :  Luminescence caused by light is called photoluminescence. Photoluminescence that stops immediately as soon as the incident light is cut off is called fluorescence. Photoluminescence that continues for an appreciable time even after the incident l...

Factors Affecting Quantum yield [1] Temperature :   The change of quantum yield with temperature is given by the equation d(logΦ)/dT = Q/RT 2 Where Φ is quantum yield and Q is the amount of heat evolved by the formation of a one-mole substance. Photochemical decomposition of ammonia increases by about 15% for every 100ํ ℃ temperature increase. It reaches seven-fold by 500 ℃. [2] Wavelength :   As frequency increases, the power of light energy increases, so quantum yield increases. In other words, the quantum yield decreases as wavelength increases. [3] Light Intensity: As light intensity decreases, quantum yield increases. [4] Inert gases: The addition of inert gases increases the quantum yield. This is because inert gases increase the number of starting chains as they may retard the diffusion of the atoms to the walls. This effect will decrease the rate of the chain-terminating steps. Thus, the rate of reaction increases thereby quantum yield increases.

Class - I: High quantum yield reactions. Reactions in which quantum yield is greater than unity are high quantum yield reactions. The quantum yield of the combination of carbon monoxide and chlorine by the light of a wavelength from 4000 to 4360 Å is 10 3 . CO + Cl 2 ➝ COCl 2 The quantum yield of the combination of hydrogen and chlorine by the light of wavelength less than 4500 Å is 10 4 to 10 6  H 2 + Cl 2 → 2HCl Photochemical decomposition of H 2 O 2 by a wavelength of about 3100 Å has a quantum yield of more than 7. 2H 2 O 2 → 2H 2 O + O 2    Class - II: Low quantum yield reactions. Reactions in which quantum yield is less than unity are low quantum yield reactions. The quantum yield of the combination of hydrogen and bromine to form HBr is about 0.01 H 2 + Br 2 → 2HBr The quantum yield of photolysis of ammonia by a wavelength 2100 Å is nearly 0.2 2NH 3 → N 2 + 3H 2 Class - III: Small integer quantum yield reactions. Reac...