Definitions of Chemistry

1. ION:- 
           An atom or group of atoms that can exist independently with a charge is called an “ION”. 
                                           (Or) 
             Loss or Gain of electrons
2. ATOM:-
           These are the smallest particle of a matter which may or may not exist independently.
3. MOLECULE:-
            These are the smallest particles of a matter which exists independently.
4. SYMBOL:-
             It is the shortest form of an element which represents the number of atoms in that.
5. EQUATION:-
             An equation represents a chemical reaction in which there are the reactants and products in symbolic form.
6. RADICAL:-
            An atom or group of atoms can exist independently with charges and are formed by loss or gain of electrons.
7. EMPIRICAL FORMULA:-
             It is the formula of a molecule that contains the least possible ratio of atoms.
8. MOLECULAR FORMULA:-
             It represents the ratio of the atoms in a molecule or a compound which are actually present in that.
9. COMPOUND:-
          Two elements combine chemically is called a compound.
10. ELEMENT:-
          It is a pure substance.
                    (Or)
           Molecules made of identical atoms.
11. MATTER:-
          Which has weight and occupies space     
12. CHEMISTRY:-
          It is the science which deals with all kinds of matter and their changes.
13. VALENCY:-
          The combining capacity of any element is called valency.

14. MOLECULAR WEIGHT:-
           The molecular weight of a molecule is the sum of weights of atoms present in it.
15. DISTILLATION:-
          Condensation followed by evaporation is called distillation.
16. SOLUTION:-
          Solid is mixed with liquid to form solution.
17. BURNING:-
           Burning means treating with oxygen 
18. CIRCUIT:-
           Containing coil is called circuit.
19. NEUTRALIZATION:-
           Forming of salts and water from basics and acids
20. SUBLIMINATION:-
           On heating some solids substances changes directly into vapor without becoming liquids. This process is known as sublimination.

21. PHYSICAL CHANGE:-
           A physical change is a change which can be brought back to the normal condition easily.
22. CHEMICAL CHANGE:-
           A chemical change is a change in which substances will change and can not be brought back to their normal condition easily.
23. CHEMICAL COMBINATION:-
           In a chemical combination two elements are compound always combines in definite ratio to form a larger compound.
24. CHEMICAL DECOMPOSITION:-
           In a chemical decomposition always a larger compound divides under special conditions into smaller compound or elements.
25. CHEMICAL DISPLACEMENT:-
            In a chemical displacement reaction the elements of higher reactivity will displace the elements of lower reactivity.
26. CHEMICAL DOUBLE DECOMPOSITION:-
            In the chemical change there will be the exchange of radicals between two compounds.
27. MIXTURE:-
            It is an impure substance which is made up of different kinds of molecules.
                                            (Or)
               If the elements or compounds are combine physically. There they form a mixture.
28. FORMULA:-
            It is the short form of a molecule.
                                           (Or)
              It represents the actual number of constituents of atoms present in the molecules.
29. RUST:-
           Iron reacts with the moist air and forms rust.
    Formula of Rust:-Fe2o3.
30. REACTANTS:-
           The substances which take part in the reaction, they should be written on the left side.                  
31. PRODUCTS:-
            The substance formed in the reaction is called products. They should be written on the right side of the arrow mark.


32. ACIDS:-
             Substances with sour taste and changing blue litmus to red
33. BASES:-
            Substance with sticky nature and changing red litmus to blue are called Alkalies or Bases.
34. LAW OF CONSERVATION OF MASS:-
                During a chemical change matter is neither created nor destroyed but it undergoes physical and chemical change.
35. LAW OF DEFINITE PROPOSITION:-
             When two or more elements combine to form a compound, they combine in a fixed ratio of their weights. The ratio is independent of the method of formation of the compound.
36. LAW OF MULTIPLE PROPOSITION:-
              The weight of one element that separately combine with a fixed weight of another element to form two or more compound tears a simple integral ratio.


37. SOFT WATER:-
          Water which produces lather sufficiently with a soap is called soft water.
38. HARD WATER:-
           Water which does not produce lather property with soap is called hard water.
39. CHLORINATION:-
           In this process a small quantity of chlorine is added to water in order to kill the microbes which cause illness.
40. OXY-HYDROGEN FLAME:-
              Hydrogen generates enormous heat (2400°c) when it burns in the presence of oxygen. It is used for cutting and welding metals.
41. HYDROGENATION OF OILS:-
            Conversion of vegetable oils into solid fats by passing hydrogen through them under pressure is called hydrogenation of oils.
42. CATALYST:-
            Catalyst is a substance which alters the rate of a chemical reaction, without itself undergoing any permanent chemical change.
43. OXIDATION:-
             The chemical reaction of any substance with oxygen or removal of hydrogen from a substance is called oxidation.
                                           (Or)
               Loss of electrons is called oxidation.
44. REDUCTION:-
           Removal of oxygen from a compound is called reduction.
                                             (Or)
             Gain of electrons is called reduction.
45. COMBUSTION:-
           Burning substances in oxygen or air is called combustion.
46. AIR POLLUTION:-
         The contamination of air by dust and toxic vapors is called air pollution.
47. ALLOTROPY:-
           The existence of an element in two or more different physical forms is called allotropy.
48. PHOSPHORESCENCE:-
           If phosphorus is exposed to air in dark, it glows because of slow combustion. This is called phosphorescence.
49. NITROGEN FIXATION:-
           Conversion of atmospheric nitrogen nitrate salts is called nitrogen fixation.
50. COMPRESSIBILITY:-
             Decrease in the volume of the same quantity of gas under pressure is known as compressibility.
51. CHEMICAL EQUATION:-
             Chemical equation is a short hand representation of a chemical change or reduction in terms of symbols and formulae.
52. OXYGEN:-
PREPARATION OF OXYGEN:-
             
                          
                          
                          
                         
                         


PHYSICAL PROPERTIES:-
              Oxygen is a colorless, tasteless and odourless gas. It is slightly heavier than air and slightly soluble in water. It is neutral to litmus. It has no effect on wet litmus paper. 
CHEMICAL PROPERTIES:-
              
                            
                           
                           
                          
OXIDATION:-
              
                            
                           
                           
REDUCTION:-
             
                           
TEST FOR OXYGEN:-
          When we introduce a burning splinter into the oxygen gas in burns brightly
53. SEDIMENTATION:-
          Water in the form of crystals is called sedimentation.

54. OXIDIZING AGENT:-
           The substance which oxidizes is known as oxidizing agent.
55. REDUCING AGENT:-
            Hydrogen which removes oxygen from the compounds is called reducing agent.
56. HYDRIDES:-
             Hydrogen reacts with many elements to form compounds is called hydrides.
57. TRICKS OF CHEMISTRY:-
             
               
               
               
58. CHARLE’S LAW:-
            At constant pressure the volume of given mass of gas increases with an increase in temperatures and decreases with decrease in temperature by a value of 1/273 of the original volume at 0°c for every one degree centigrade change in temperature.
59. CHEMICAL BOND:-
            The atom in a molecule is held together by forces of attraction and this force is called a chemical bond.
60. ELECTRONIC CONFIGURATION:-
            It is defined as a systematic arrangement of electrons in the atomic orbits.
61. COVALENT BOND:-
           A bond formed by the sharing of a pair of electrons between two atoms each atom contributing one electron to the shared pair is called covalent bond.
62. COVALENT MOLECULE:-
          Molecules whose atoms are joined by covalent bonds are called covalent molecules.
63. BOND DISSOCIATION ENERGY:-
           Energy which is required to break the bond is called bond dissociation energy.


64. BOND ENERGY:-
             The certain amount of energy which is released when a new bond is formed is called bond energy.

65. ENDOTHERMIC REACTION:-
            It is a chemical reaction which takes place with the absorption of heat.   
66. EXOTHERMIC REACTION:-
             It is a chemical reaction which is accompanied by the release of heat energy.  
                                               (Or)
                Reaction in which heat is evolved is known as exothermic reactions.                 
67. ELECTROCHEMICAL REACTIONS:-
              The reactions which take place only with the absorption of electrical energy are called electrochemical reactions.
68. GRAM MOLECULAR WEIGHT:-
           It can be defined as the relative molecular mass of a substance expressed in grams with reference to the atomic weight of hydrogen.
69. THERMOCHEMICAL REACTIONS:-
            Equations representing heat energy in chemical reactions are called thermo chemical reactions.
70. FAST REACTIONS:-
             Reactions which take place within a second are known as fast reactions.


71. MODERATE REACTION:-
              Reactions taking place in a few minutes to a few hours is termed as moderate reactions.
72. SLOW REACTIONS:-
              Reactions taking place in several hours and above are known as slow reactions.
73. MINERALS:-
           Compounds of metals which occur in nature with other materials such as sand, rock and clay as impurities and which are obtained by mixing are called minerals.
74. ORES:-
          The minerals from which metals can be profitably extracted are called ores.
75. METALLURGY:-
          The method of extraction of the metals from their ores and the preparation of alloys is called metallurgy.

76. ORE DRESSING OR CONCENTRATIONS:-
           The removal of unwanted impurities by mechanical and other physical methods is known as ore dressing or concentration.
77. CALCINATION:-
           It is a process in which ore is subjected to the action of heat in the absence of air.
78. ROASTING:-
            It is a process in which ore is heated in the presence of air.
79. MONOATOMIC:-
            The atom which has single atom is called mono atomic.
80. DIATOMIC MOLECULES:-
            The molecule which has two atoms is called diatomic molecules.
81. CONSTITUENTS:-
             The substances present in the mixture are called constituents.
82. DECANTATION:-
             Separating a clean liquid from the solid sediment is called decantation.
83. FILTRATION:-
            It is a process of separating very fine undissolved solid particles present in a liquid quickly or completely.
84. EVAPOURATION:-
            It is a process in which we get back the dissolved solid from a solution by heating.

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