THE COMPLETE GENERAL SCIENCE NOTES (CHEMISTRY)
S.NO. Content Page number
1 Chemical reaction and equation 2
2 Matter 7
3 Atoms and molecules 13
4 Carbon and its compounds 16
5 Periodic classification of electrons 18
6 Coal and petroleum 24
7 Acids, bases and salts 25
8 Metals and nonmetals 28
9 Important chemicals and their uses 33
10 Important chemistry one lines 34
CHEMICAL REACTIONS AND EQUATIONS
CHEMICAL REACTION & EQUATIONS
A complete chemical equation represents the reactants, products and their physical
state symbolically.
Following observations help us to determine whether a chemical reaction has taken
place
• Change in state
• Change in color
• Evolution of a gas
• Change in temperature
Some of the examples of chemical reactions in everyday life.
• Photosynthesis
• Aerobic cellular respiration
• Combustion of wood
• Rusting of iron
• Metathesis
• Digestion
• Cooking an egg
• Souring of milk
• Rotting bananas
• Reactions in which heat is given out along with the products are called exothermic
reactions
• Reactions in which energy is absorbed are known as endothermic reaction.
BALANCED CHEMICAL EQUATIONS
Mass can either be created nor destroyed in a chemical reaction. That is, the total mass of
the elements presents in the products of a chemical reaction has to be equal to the total
,mass of the elements present in the reactants. The number of atoms of each element
remains the same, before and after a chemical reaction.
Some of the example of balanced equations
Zn+ H2SO4→ ZnSO4+H2
3Fe+ 4H2O→ Fe3O4+ 4H2
TYPES OF CHEMICAL REACTIONS
1. COMBINATION REACTION
In a combination reaction two or more substances combine to form a new single
substance. Example of combination reaction
Calcium oxide reacts vigorously with water to produces slaked lime (calcium hydroxide)
releasing a large amount of heat.
CaO(s)+ H2O--> Ca(OH)2 + heat
A solution of slaked lime produced by the above reaction is used for whitewashing wall.
2. DECOMPOSITION REACTION
Decomposition reactions are opposite to combination reactions. In a decomposition
reaction, a single substance decomposes to give two or more substances.
In this reaction you can observe that a single reactant breaks down to give simpler
products. This is a decomposition reaction.
2FeSO4(s)+ Heat-> Fe2O3(s)+ SO2(g)+ SO3(g)
Decomposition of silver bromide into silver and chlorine by light.
2AgBr(s)+ sunlight -> 2Ag(s)+ Br2(g)
Silver bromide used in black and white photography.
3. DISPLACEMENT REACTION
When an element displaces another element from its compound, a displacement
Reaction occurs.
Fe+ CuSO4--> FeSO4+ Cu
In this reaction, iron has displaced or removed another element copper from copper
sulphate solution. This reaction is known as displacement reaction.
4. NEUTRALISATION REACTION
When an acid and a base react together to form salt and water known as
neutralization reaction.
HCl+ NaOH→ H2O+ NaCl
5. OXIDATION AND REDUCTION
• Reactions also involve the gain or loss of oxygen or hydrogen by substances.
• Oxidation is the gain of oxygen or loss of hydrogen and loss of electrons.
, • Reduction is the loss of oxygen or gain of hydrogen and gain of electrons.
• Increases valence of an element is oxidation while decreases valence of
element is reduction.
• Increase in oxidation number is called oxidation while decreases in oxidation
number is called reduction. Example-
CuO+ H2-> Cu+ H2O
During this reaction the copper oxide is losing oxygen and is being reduced. The
hydrogen is gaining oxygen and is being oxidized.
OXIDATION AND REDUCTION AGENTS
• Substances that loses oxygen or gains hydrogen is known as an oxidizing
agent.
• Substances that loses hydrogen or gains oxygen is known as a reducing agent.
• Compounds with oxygen atom are called oxidizing agent and compounds
with hydrogen atom are called reducing agent.
• Some compounds can act as either oxidizing agents or reducing agents. One
example is hydrogen gas, which acts as an oxidizing agent when it combines
with metals and as a reducing agent when it reacts with non -metals.
RANCIDITY
When oils and fats or food containing oils and fats are exposed to air, they get
oxidized due to which the food becomes stale and gives a bad taste or smell. This is
called Rancidity. Following ways to preventing rancidity.
• Adding antioxidants
• Refrigerating
• Storing food in airtight containers with nitrogen gas.
COMMON NAME AND FORMULA OF CHEMICAL COMPOUNDS
Chemical compounds Chemical formula Common names
Calcium oxide CaO Quick lime
Calcium hydroxide Ca(OH)2 Slaked lime
Calcium carbonate CaCO3 Lime stone
Trichloro methane CHCl3 Chloroform
Calcium oxychloride CaOCl2 Bleaching powder
Sodium hydrogen carbonate NaHCO3 Baking soda
Sodium carbonate Na2CO3 Washing soda
Calcium sulphate hemihydrate CaSO4.1/2H2O Plaster of paris
Calcium sulphate dihydrate CaSO.2H2O Gypsum
Acetic acid CH3COOH Vinegar
Silicon oxide SiO2 Sand
Methane CH4 Marsh gas
Nitrous oxide N2O Laughing gas
S.NO. Content Page number
1 Chemical reaction and equation 2
2 Matter 7
3 Atoms and molecules 13
4 Carbon and its compounds 16
5 Periodic classification of electrons 18
6 Coal and petroleum 24
7 Acids, bases and salts 25
8 Metals and nonmetals 28
9 Important chemicals and their uses 33
10 Important chemistry one lines 34
CHEMICAL REACTIONS AND EQUATIONS
CHEMICAL REACTION & EQUATIONS
A complete chemical equation represents the reactants, products and their physical
state symbolically.
Following observations help us to determine whether a chemical reaction has taken
place
• Change in state
• Change in color
• Evolution of a gas
• Change in temperature
Some of the examples of chemical reactions in everyday life.
• Photosynthesis
• Aerobic cellular respiration
• Combustion of wood
• Rusting of iron
• Metathesis
• Digestion
• Cooking an egg
• Souring of milk
• Rotting bananas
• Reactions in which heat is given out along with the products are called exothermic
reactions
• Reactions in which energy is absorbed are known as endothermic reaction.
BALANCED CHEMICAL EQUATIONS
Mass can either be created nor destroyed in a chemical reaction. That is, the total mass of
the elements presents in the products of a chemical reaction has to be equal to the total
,mass of the elements present in the reactants. The number of atoms of each element
remains the same, before and after a chemical reaction.
Some of the example of balanced equations
Zn+ H2SO4→ ZnSO4+H2
3Fe+ 4H2O→ Fe3O4+ 4H2
TYPES OF CHEMICAL REACTIONS
1. COMBINATION REACTION
In a combination reaction two or more substances combine to form a new single
substance. Example of combination reaction
Calcium oxide reacts vigorously with water to produces slaked lime (calcium hydroxide)
releasing a large amount of heat.
CaO(s)+ H2O--> Ca(OH)2 + heat
A solution of slaked lime produced by the above reaction is used for whitewashing wall.
2. DECOMPOSITION REACTION
Decomposition reactions are opposite to combination reactions. In a decomposition
reaction, a single substance decomposes to give two or more substances.
In this reaction you can observe that a single reactant breaks down to give simpler
products. This is a decomposition reaction.
2FeSO4(s)+ Heat-> Fe2O3(s)+ SO2(g)+ SO3(g)
Decomposition of silver bromide into silver and chlorine by light.
2AgBr(s)+ sunlight -> 2Ag(s)+ Br2(g)
Silver bromide used in black and white photography.
3. DISPLACEMENT REACTION
When an element displaces another element from its compound, a displacement
Reaction occurs.
Fe+ CuSO4--> FeSO4+ Cu
In this reaction, iron has displaced or removed another element copper from copper
sulphate solution. This reaction is known as displacement reaction.
4. NEUTRALISATION REACTION
When an acid and a base react together to form salt and water known as
neutralization reaction.
HCl+ NaOH→ H2O+ NaCl
5. OXIDATION AND REDUCTION
• Reactions also involve the gain or loss of oxygen or hydrogen by substances.
• Oxidation is the gain of oxygen or loss of hydrogen and loss of electrons.
, • Reduction is the loss of oxygen or gain of hydrogen and gain of electrons.
• Increases valence of an element is oxidation while decreases valence of
element is reduction.
• Increase in oxidation number is called oxidation while decreases in oxidation
number is called reduction. Example-
CuO+ H2-> Cu+ H2O
During this reaction the copper oxide is losing oxygen and is being reduced. The
hydrogen is gaining oxygen and is being oxidized.
OXIDATION AND REDUCTION AGENTS
• Substances that loses oxygen or gains hydrogen is known as an oxidizing
agent.
• Substances that loses hydrogen or gains oxygen is known as a reducing agent.
• Compounds with oxygen atom are called oxidizing agent and compounds
with hydrogen atom are called reducing agent.
• Some compounds can act as either oxidizing agents or reducing agents. One
example is hydrogen gas, which acts as an oxidizing agent when it combines
with metals and as a reducing agent when it reacts with non -metals.
RANCIDITY
When oils and fats or food containing oils and fats are exposed to air, they get
oxidized due to which the food becomes stale and gives a bad taste or smell. This is
called Rancidity. Following ways to preventing rancidity.
• Adding antioxidants
• Refrigerating
• Storing food in airtight containers with nitrogen gas.
COMMON NAME AND FORMULA OF CHEMICAL COMPOUNDS
Chemical compounds Chemical formula Common names
Calcium oxide CaO Quick lime
Calcium hydroxide Ca(OH)2 Slaked lime
Calcium carbonate CaCO3 Lime stone
Trichloro methane CHCl3 Chloroform
Calcium oxychloride CaOCl2 Bleaching powder
Sodium hydrogen carbonate NaHCO3 Baking soda
Sodium carbonate Na2CO3 Washing soda
Calcium sulphate hemihydrate CaSO4.1/2H2O Plaster of paris
Calcium sulphate dihydrate CaSO.2H2O Gypsum
Acetic acid CH3COOH Vinegar
Silicon oxide SiO2 Sand
Methane CH4 Marsh gas
Nitrous oxide N2O Laughing gas
