Metals and Non-Metals,

                                                    Metals and Non-Metals

There are about 116 known elements. these elements are divided into three main category

• Metals  eg gold,silver
• Non-Metals      eg. phosphorous
• Metalloids    eg.  Arsenic and antimony

                                                 Metals

There are about 80 elements which are metals.Well metals can be defined as those elements which readily lose electrons to form positive ions called cations.

                                     

• There are some metals which do not react  readily with other elements are called rare metals eg gold and platinum. 
• Aluminium is the most abundant metal in the earth's crust followed by iron.
• Ores:The minerals from  which metals can be extracted profitably and conveniently are called ores.
• Metals ores commonly occur as carbonates,sulphides,oxides,chlorides  and halides.

Physical Properties:

• Ductile: They can be drawn into wires.
• Malleability: They can be beaten into  thin sheets.
• Solid: They are usually solid at room temperature except Mercury which is liquid at room temperature.
• Hardness and Tensile strength: Generally very hard and very strong except sodium and potassium.
• M.P and B.P: Very high M.P and B.P.
• Conductivity: Good conductor of heat and electricity exception mercury and tungsten
• Density: High density except sodium and potassium
• Lustre: brilliant shine 
• Sonority: Metals are sonorous i.e they make a metallic sound which distinguishes them from a non-metals. except mercury.

Chemical Properties :

        Some metals are more reactive than others thus they are arranged in series according to their reactivity. Hydrogen is the only non-metal that is included in this series.

• Reaction with oxygen: Metal react with oxygen to form basic oxides.

                  2Mg                     + O2                ------>             2MgO

                 Magnesium            Oxygen                              Magnesium Oxide

• Reaction with water: Metals react with water to form basic oxide or hydroxide and release hydrogen gas.

              Sodium    +      water                   ------------>  sodium hydroxide   + hydrogen

• Reaction with dilute mineral acids:   Metals with  dilute mineral acid under different conditions to form metal salts and evolve hydrogen gas.

               Metal  + Dilute acid-------------> Metal salt  +  hydrogen

•       Reaction with salt solution: Metal react with salt solutions of different metals.

                   Cu      +    FeSO4    -------->  No reaction

                    Mg    +  CuSO4     --------> mgSO4     +   Cu

  

Microorganisms

                                  Kalpana Coaching Classes      


Microorganisms are very small organisms that   are harmful and causes diseases,often called germs.
they are so small to be visible  to naked eyes hence called microbes  or microorganisms.
                   They are present almost everywhere such as air,water, deserts,food,inside your body etc.
In unfavourable condition,microbes develope a hard outer covering around themselves as cyst.They  remain inactive within the cyst till favourable condition are present.

                                CLASSIFICATION OF MICROORGANISMS

Microbes are classified into 5 major group
Bacteria - They are simple, single celled organisms.They are of three shape

•  bacillus(rod-shaped),
• cocci(spherical) and 
• spirilla(spiral- shaped).They are autotrophic,saprotrophic,heterotrophic.

1. Algae-They are autotropic organism with undifferentiated plant bodies.They are found in aquatic habitats.eg. Chlamydomonas,Spirogyra,Laminaria
2. Fungi- They are plant-like organism that are heterotrophic (saprophytic and parasitic)in nutrition.
3. Protozoa-Unicellular organisms and have properties like animals.They are mostly heterotrophic.They have locomotory structures that allow them to move around.eg Amoeba and Paramecium.
4. Viruses - They are the smallest microorganisms.They have the characteristics of living as well as non-living organisms.They enter the  living cell and divide,  when outside they act as non-living as they lack the cell-organelle for multiplication,they often kill the host cell.

                                              MICROBES ARE USEFUL ALSO

1. Some Blue Green Algae and bacteria are able to fix nitrogen from the atmosphere into the soil.They are found in the roots of the leguminous plant peas,beans(eg Rhizobium bacteria).This process is called Nitrogen Fixation .
2. Lactobacillus bacteria are used for preparing curd,cheese,pickles and other food item.Lacto bacillius bacteria are actually good bacteria and help us in digesting milk.When present in guts in adequate amount helps in digestion.
3. Yeast(fungus) often used in baking and brewery help in converting glucose present in food into ethyl alcohol and carbon di oxide.This process is called Fermentation.
4. They are used in preparing antibiotics also like Penicillin.Penicillin is obtained from fungus Penicillin notatum.this fungus is helpful in destroying  staphyllococcus bacteria.
5. Vaccines developed  for Thypoid,Tuberculosis,measles,polio,small pox etc are obtained from microorganisms only.Vaccines is a suspension of dead or weak microbes.Thwy are used to build immunity to our body.
6. In Ruminating Animals like cow,sheep etc some bacteria and protozoa resides in their stomach and help in digestion of cellulose.
7. Some bacteria like Psudomonas decompose sewage and other wastes in water.This helps in cleaning  the environment and water.
8. Bacteria  are also used in leather industry and  tea