Shikshakendra

Nutrition in plants Green plants are unique in that they can prepare their own food by using simple inorganic substances carbon dioxide and water.  The process by which plants prepare their food is known as photosynthesis. Photosynthesis: Photosynthesis may be defined as the process by which green parts of the plants prepare their food in the presence of sunlight by obtaining carbon dioxide from air and water from the soil. Photosynthesis can be represented by equation:  6CO 2 +  12H 2 O    ➡ C 6 H 12 O 6   +  6H 2 O  +  6O 2 Photosynthesis is an oxidation-reduction process in which water is oxidised to oxygen and carbon dioxide is reduced to sugars.  Photosynthesis takes place in two stages: • light Reaction • Dark Reaction Requirements for photosynthesis: 1. Photosynthetic pigments 2. Carbon dioxide 3. Water 4. Sunlight

 Autotrophic Nutrition The word autotrophic has been derived from two Greek words auto meaning self & trophe means nutrition. In this type of Nutrition, living organisms synthesis their own food from the inorganic substances by the utilisation of energy. The organisms shows this types of Nutrition are called autotroph.  Autotrophic is of two types: 1. Photosynthetic Nutrition:  The green plants, most of the algae and some bacteria synthesize their food in the form of simple sugar from inorganic substances, carbon dioxide & water, in the presence of sunlight & chlorophyll. These organisms are known as photoautotrophic & the process is called photosynthesis. 2. Chemosynthetic Nutrition:  Some bacteria synthesize their Organic food from inorganic substances by utilising energy released from oxidation of simple organic compounds. These are known as chemoautotrophic and the process is called chemosynthesis, ex. Sulphur bacteria, iron bacteria, Nitrosomonas...

 What are life processes? A number of processes are essential for maintenance of life. These processes are called life processes. • Every organism require energy for the various maintenance processes. This energy is provided by food. So, a process is required to intake food & convert it into simpler forms which can be absorbed by body. This process is called nutrition.  • A process is also required to obtain energy from the simpler food forms present in each cell. This is done by the process called respiration. In which organisms obtain Oxygen from outside & utilize it to break down food substances for cellular needs along with the release of carbon dioxide. Respiration is oxidation reaction. • Process is required to transport these substances from one part of the body to other. This takes place by the process called transportation & the system involved in the process called Transportation process. • A number of metabolic reactions occur in the various parts of the...

Formation of Covalent Bonds 1.  Single Covalent Bonds:   • Formation of Hydrogen molecules:                   The atomic number of hydrogen is 1. Hence, hydrogen has one electron in its K shell & it requires one more electron to fill the K shell. So the two hydrogen atoms share their electrons to form a molecule of hydrogen. This allows each hydrogen atom to attain the stable electronic configuration of the nearest noble gas, helium, which has two electrons in its K shell. We can depict the formation of diatomic molecule of hydrogen using dots or crosses to represent valence electrons involved in sharing. Such structures of molecules are known as electron dot structures. The shared pair of electrons is said to constitute a single bond between the two hydrogen atoms. A single bond is also represented by a line between the two hydrogen atoms. Since, each hydrogen atom shares one electron to form Hydrogen molecule, thus t...

             ALLOYS An alloy may be defined as homogeneous mixture of two or more metals, or a metal & a non-metal.  The properties of any metal can be changed if it is mixed with some other metal or non-metal. This mixture is called ALLOYS. Preparation of Alloys: An alloy is generally manufactured by first melting the main Metal and then dissolving the other elements in it in a definite proportions. It is then cooled to room temperature. Types of Alloys: 1. Ferrous Alloys:   An alloy in which iron is present as one of the constituents is known as a ferrous alloy.  For ex,  nickel steel (iron=96-98%, ni=4-2%) & manganese steel ( Fe=86%, Mn=13%, C=1%) etc. 2. Non ferrous Alloys:   An alloy which does not contain iron as one of the constituents is known as a non- ferrous alloy. For ex, brass ( cu= 80%, zn=20%), bronze( Cu=90%, Sn=10%), etc. 3. Amalgams:   An alloy which contains mercury as one of the c...

 Carbon is unique element. It is non-metal with symbol C. The carbon compounds are also known as organic compounds. BONDING IH CARBON- THE COVALENT                                                           BOND Melting & boiling points if carbon compound are very low. This is beacuse the force of attraction between the molecules are not strong.  Most of the carbon compounds are poor conductors of electricity. It means the bonding in these compounds is such that it does not give rise to any ion. • Carbon always form a covalent bond COVALENT BOND:  A chemical bond which is formed between two atoms by mutual sharing of valence electrons between two atoms such that each atom attains the stable noble gas electron configuration, is known as a covalent bond.  The number of electrons contributed by each atom for sharing is ...

           CORROSION The process of slowly eating up of metals due to their conversion into oxides, carbonates, sulphides, sulphates, etc. by the action of atmospheric gases & moisture is called Corrosion. 1. The surface of silver metal gets tarnished when exposed to air. This because it reacts with Sulphur in the air to form a coating of black silver sulphide. 2. Copper objects lose their lustre or shiny brown surface after sometime. This is beacuse when the surface after sometime. This is because when the surface of copper remain exposed to air, it's Surface is attacked by moist carbon dioxide present in the air forming a green coating of basic copper carbonate.  • Rusting of Iron When iron is exposed to moist air for a long time, it's surface acquires a coating of brown, flaky substance called rust. This is due to attack of oxygen & water vapour present in the air on the surface of iron. It is called rusting of Iron. • Prevention of rusting:...

Step 1. Enrichment of ore: First step in the metellurgy is, thus, to remove these unwanted impurities from ore such that concentration of metal in the ore increases, that is ore enriched in the metal.  Some methods are used for concentration of the ore: 1. Hydraulic Washing:   This method is used for the enrichment of oxide ores of heavy metals like lead, tin, iron etc.  In this method, the ore is crushed & finally powdered. The powdered ore is washed with a stream of water. The gangue particles, being lighter, are washed away with water, while heavy ore particles are left behind. 2. Froth Floatation process:   This method is used for the enrichment of sulphide ores, especially those of copper, zinc & lead. The method is based on the principle of difference in different wetting properties of ore & gangue. 3. Chemical Seperation:   This method is also called the leaching. This method bases on the difference in the chemical reactivity of...

 MINERALS The inorganic elements or compounds which occur naturally in the earth's crust. When the minerals are mined from the earth's crust, they are always contaminated with earthy, sandy and Rocky impurities, These earthy, sandy & Rocky impurities associated with the mineral are known as gangue or matrix.     ORES Those minerals from which the Metals can be extracted convenientally  & economically are known as ores. An ore contains a good or high concentration of metal & low impurities that can be removed easily & economically. All ores are minerals but all minerals are not ores. Extraction of Metals ( metallurgy) An ore may contain the metal in the elementary state or in the form of its compounds along with some impurities such as soil, sand etc. Getting metal out of it's ore is termed as extraction of metal. The various steps involved in the extraction of metal from its ores, followed by refining of the metal are known as metallurgy. Processes em...

Properties of ionic compounds: 1. Physical Nature:   Most of the ionic compounds are crystalline solids. Ionic compounds are relatively hard because of the strong electrostatic forces of attraction between the oppositely charged ions, Positive & negative ions. These compounds are generally brittle & break into pieces when pressure or force applied. 2. Melting points & boiling points: Ionic compounds have high melting points. This is because in the ionic compounds, the oppositely charged ions are held together by strong electrostatic forces of attraction. 3. Solubility: Ionic compounds are generally soluble in water but insoluble in organic solvents like benzene, alcohol, ether, kerosene, petrol, chloroform etc. 4. Colour in the flame: Most of the salts when brought into flame, impart characteristics colours to the flame. 5. Electrical conductivity: The conduction of electricity through a solution involves the movement of charged particles. Ionic compounds, in the s...

      IONIC COMPOUNDS  An electrically charged atom of an element is called Ion.  • An ion is formed by gain or loss of electrons by an atom of an element, thus, it contains an unequal number of electrons & protons. • The metal atom which loses the electron becomes a positive ion while the non-metal atom which gain electrons becomes a negative ion and the bond form between them is known as ionic bond or electro valent bond. Ions are classified as cation & anion 1. Cation:   When atom loses electrons, the number of electrons becomes less than the number of protons. Thus, the species formed has a positive charge. It is known as cation. • Formation of sodium ion, Na     Atomic number of sodium= 11   Electronic configuration= K  L  M                                                  2   ...

CHEMICAL PROPERTIES OF NON-METALS: Non-Metals readily form negatively charged ions by gaining electrons. 1. Reaction with oxygen: On heating, non-metals react with oxygen to form oxides. These oxides may be either acidic or neutral. They never form basic oxides. The non-metallic oxides are covalent compounds in nature because they are formed by sharing of electrons between the Non-metal& the oxygen atom. • Reaction of carbon with oxygen:  When carbon burns in excess of air, it forms carbin dioxide.                C   +   O 2       ➡       CO 2 • Reaction of sulphur with oxygen:  when sulphur is burnt in Air, it reacts with oxygen to form sulphur oxide.           S     +     O 2      ➡    SO 2 • Reaction of phosphorus with oxygen:  phosphorus reacts with excess of oxygen to form phosphorus pentoxide, w...

CHEMICAL PROPERTIES OF METALS: 1. Reaction of Metals with oxygen present in Air:   Most of the metals react with oxygen to give metal oxides.       Metal  +  oxygen   ➡  Metal oxide. • Reaction of highly reactive metals such as sodium, pottasium & lithium with oxygen: Sodium, pottasium & lithium are highly reactive metals. These metals react with oxygen present in Air, even at room temperature.            4Na  +  O 2     ➡  2Na 2 O             4K   +  O 2     ➡  2K 2 O             4 Li  +  O 2     ➡   2Li 2 O Sodium, potassium & lithium are stored in kerosene oil in order to protect them from atmospheric moisture & oxygen. • Reaction of less reactive metals like magnesium, aluminum & zinc with oxygen:  Magnesium reacts with oxygen in Ai...

  METALS & NON- METALS  Metals: • Metals are those elements which possess lustre when freshly cut and are malleable and ductile and good conductor of heat & electricity. • Metals are those element which lose electrons and form positive ions.   Malleable: It means which can be beaten with hammer to form thin sheets without breaking. Ductile: It means which can be drawn into wires. Importance of Metals: Metals are of great importance in our everyday life. They are used for a large number of purposes. • Utensils used at home are made of metals. • Metals are used in the construction of buildings and bridges. • In making of almost all types of machine parts. • In the manufacture of automobiles, aeroplanes, ships, trains etc.  • Silver & gold are used in making of jewellery. Non-Metals: • Non metals are those elements which do not possess lustre & are neither good conductor of heat& Electricity nor malleable & ductile but are brittle. • Non-met...

 SALTS: Salts are the ionic compounds which consist of two parts, one part carrying a positive charge called ion or cation. The other part carrying a negative charge called ion or anion. Family of salts: Classification of salts on the basis of Acids from which they are obtained: • chloride salts:  sodium chloride, potassium chloride, calcium chloride etc. • Nitrate salts:  sodium nitrate, potassium nitrate, calcium nitrate etc. • Sulphate salts:  Sodium sulphate, potassium sulphate, calcium sulphate, magnesium sulphate etc. • Carbonate salts:  sodium carbonate, potassium carbonate, calcium carbonate.  COMMON SALT ( SODIUM CHLORIDE) Chemical name of common salt is sodium chloride. Common salt is also known as   "Table salt" or just salt. Occurence & Extraction of common salt: 1. common salt from seawater:   seawater contains many salts dissolved in it, most of which is sodium chloride. 2. Common salt from underground:. Common salt is ...

CHARACTERISTIC PROPERTIES OF ACIDS: • Sour Taste:   Acids have sour taste. • Action on litmus:.  Acids turn blue litmus solution to red. • Action on methyl Orange:.  When a drop of methyl Orange is added to an acidic solution, it turns solution red. • Reaction with Metals to form Hydrogen gas:.  When acids react with active metals a salt is formed with the evolution of hydrogen gas. Metal + Acid    ➡ Metal salt + hydrogen gas     Zn  +    2HCl       ➡      ZnCl 2   + H 2 •Reaction with Bases to form salt and water:      Acid +   Base     ➡    Salt   +   Water     HCl   +   NaOH   ➡    NaCl  +  H 2 O The reaction between an acid and a base to give a salt and water is known as neutralization reaction. •Reaction with Metal oxides to form salt & water:   ...

On the basis of their chemical properties all the compounds can be classified into 3 categories. 1. Acids.             2.Bases.            3. Salts. ACIDS: Acids are substances having a sour taste. Many fruits are sour because they contains acids.  Examples: vinegar, tomatoes, lemon juice etc. • Organic Acids ( naturally occurring): The Acids produced by plants & animals (except hydrochloric acid). Ex.  Ethanoic acid.   • Mineral Acids: The Acids formed from minerals present in the earth's crust. Ex.  Nitric Acid.           Name of Acid              Source Plants.      Citric Acid                orange & lemon                 Tartaric Acid.          Tamarind & grapes              ...

TYPES OF REACTIONS: DETAILED   • Combination reaction: Those reaction in which two or more chemical substances (elements & compounds) combine together to form a single chemical substance.   Ex.    Mg  + O 2   ➡    2MgO • Decomposition reaction: Those reactions in which a single chemical substance breaks down to give two or more simpler substances.  Ex. • Thermal decomposition:       FeSO 4 . 7H 2 O    ➡  FeSO 4   + 7H 2 O     •Electrolytic decomposition:        2H 2 O    ➡   2H 2   +  O 2 •photo decomposition:     2AgCl    ➡   2Ag   +   Cl 2 • Displacement reaction:                       Reactivity series. Those reactions in which a more active element displaces a less active element from its compound. Ex.   Fe  + CuSO 4  ...