Class 12th chemistry

  The important postulates of Werner's theory of coordination compound are: 1. Metals possess two different sports of valency:  primary or ionizable valency and secondary or non-ionizable valency. 2. The central metal atom has a fixed number of secondary valencies (that is the coordination number), e.g., Co (lll) or Pt-(lV) have six secondary valencies while Cu (ll) or Pd (ll) have four secondary valencies. 3 . Primary valencies are satisfied by only -ve ions while secondary valencies may be satisfied by -ve ions or neutral molecules. 4 . Having established the number of secondary valencies, Werner attempted to find the shape of the complex. For example, six secondary valencies, are directed towards the corners of a regular octahedron, four secondary valencies are directed towards the four corners of a square-planar or tetrahedral.

 Disaccharides are those carbohydrates which upon hydrolysis produce two molecules of monosaccharides, e.g., sucrose, maltose, etc. 

 Non reducing sugars are those carbohydrates which cannot reduce Tollen's reagent or Fehling solution, e.g., sucrose. 

 Reducing sugars are those carbohydrates which can reduce Tollen's reagent or Feeling solution e.g., glucose, maltose, etc

 Polysaccharides are those carbohydrates which can be hydrolysed to yield a large number of molecules of monosaccharides e.g., cellulose, starch, etc. 

 Oligosaccharides are those carbohydrates which can be hydrolysed to yield 2-9 molecules of monosaccharides, e.g., sucrose, matlose, raffinose, etc. 

Monosaccharides are those carbohydrates which  cannot be  hydrolysed  to  smaller molecules.For example, glucose,  fructose, etc. 

Carbohydrates are polyhydroxyaldehydes or the substances that will give rise to such compounds on hydrolysis. 

 Alcohols in general are used as solvents and as a fuel. However, ethyl alcohol is mainly used as an important beverage. Ethers are used as solvents, anaesthetic and as a refrigerant. Phenol is used as an antiseptic, in manufacture of drugs, plastics etc. 

These are less  reactive but C-O bond  is under drastic conditions with hydrogen halides. 

The boiling point of ethers are comparable To those of Alkanes of comparable molecular masses but are much lower than those of alcohol because of week polarity of ethers. The solubility of ethers with water resembles those of alcohols of the same molecular mass. This is because like alcohols, oxygen of ether can also form H-bonds with water molecules. 

 Chelate is defined as a ring structure formed by the combination of a ligand having two or more donor sites with a metal ion. The ligand having two or more Donor groups is called a chelating ligand and the method of formation of chelates is called chelation. 

 Ligand is the ion or natural molecule which is bound to the the central metal  atom or ion in the coordination entity. When it is bound to the metal ion through single donor atom then it is called unidentate ligand.

 The elements in which the additional electron fills the inner f-orbitals are called f-block elements. 

 The atoms of of which have two outermost orbits incomplete are known as transition elements. They also possess partially filled d-orbitals. 

Emulsions  are  colloids  in  which  both  the dispersed phase and the dispersion medium are liquids. 

 Molecularity of a chemical reaction means the number of reacting particles which Must collide simultaneously to bring about the chemical change

Chemical Kinetic is that branch of chemistry which deals  with the  rates  of chemical reactions and their mechanism

 Colligative properties of ideal solution are those properties which depend upon the number of moles of the solute and not at all upon their nature or composition. 

 Normality (abbreviated N) is the number of equivalents of solute per litre of solution.

 Molarity (abbreviated M) of a solution is the number of moles of the solute present in one litre of the solution

 Molality of a solution is the number of moles of the solute present in 1000 grams of the solvent. 

 Metallic solids such as silver or iron are like covelent network solids, but they consists of metal atoms. 

 Molecular solids are those like sucrose or ice, whose constituent particles are molecules held together by the intermolecular forces. 

 Amorphous solids, by contrast, are those whose constituent particles are randomly arranged and have no ordered long-range structure, e.g., glass, rubber, etc. 

 Crystalline solids are those whose atoms, ions, or molecules have an ordered arrangement extanding over a long-range, e.g., sodium chloride, diomond, etc.