All living orgaisms oxygen to survive. All animals and plants used oxygen in respiration. Therefore it is also called Pranavayu. It was names oxygen by the scientist Levoshe.
Oxygen is formed in the largest quantity of elements fund on Earth. About half of the top surface of the land is oxygen. It is 21% in air and 89% in water.
The structure of an oxygen atom consists of eight protons and eight neutrons in the nucleus.
The two oxygen atoms 'O' and 'O' interact chemically to form one molecule of oxygen gas. It is spelled O2 as a symbol.
Oxygen has atomic number 8, atomic weight and mass number 16 and valency 2. Trees make oxygen gas by photosynthesis.
Properties Of Oxygen
(i) This gas is colorless and odorless.
(ii) This gas is less soluble in water, somewhat heavier then air.
(iii) In the presence of oxygen, the match stick burns more rapidly with red light. In this process, the carbon present in the matchlet burns with oxygen to form carbon dioxide gas. C + O2 --------> CO2
Oxygen Uses
(i) Oxygen is helpful in burning things.
(ii) Oxygen is necessary for respiration in animals and plants.
(iii) Aquatic animals and plants use oxygen dissolved in water in respiration.
Atomic number 15, atomic weight 31, electronic structure 1s22s22p63s23p3
formula 31/15 P, valency +3, +5.
Scientist Brand of germany discovered Phosphorus in 1669. He first obtained this element by distillation of urine, sand and coal, As this element shines in the darkness. Hence, it was named Phosphorus.
It is not found in free state in nature, as it is highly functional. It is found in the form of compounds in nature in the joint state.
Phosphorus impurities
These are several allotropes of phosphorus of which white, red and black phosphorus are the main ones.
(i.) White Phosphorus-
White phosphorus is white in pure state but gradually becomes yellow, it has a garlic like odor and is poisonous. It is a molecular solid consisting of quadratically arranged P4 units. The value of P-P-P bond angle is 60' and there is more tension in the structure. This is why white phosphorus is more active. In the presence of air, it catches fire, so it is kept in cold water. It is soft and can be easily cut with a knife.
(ii.) Red Phosphorus-
The structure of red phosphorus is a complex chain structure. It is odorless and has a high threshold. The red phosphorus has a P-P-P bond angle of 100' .
(iii.) Black Phosphorus-
Black phosphorus is more stable due to its flaky structure. There are many layers of phosphorus atoms attached to it. It is also odorless like red phosphorus.
The formation of black phosphorus and red phosphorus from white phosphorus can be explained by it.
Use Of Phosphorus
(1.) White phosphorus is used in making smoke balloons, fireballs, fire sports demonstrations and colorful flashing matches.
(2.) Red phosphorus is used in making matches.
(3.) Red phosphorus is used in making an alloy called phosphorus bronzes. This alloy contains copper, tin and phosphorus.
(4.) Phosphorus compounds, zinc phosphorus and calcium phosphide are used as rat medicine.
When boiling sulfur is poured into cold water, a soft material similar to rubber is obtained which is called plastic sulfur. It is a temporary alteration of sulfur which gradually converts to rhombic sulfur.
(ii.) Δ (Delta) Sulfur or Milk Sulfur-
It is a white colored non-crystalling sulfur. It is used in making medicines.
(iii.) Colloid Sulfur-
This form of colloidal sulfur is obtained by flowing H2S gas in dilute nitric acid.
H2S + 2HNO3(meager)----------> 2NO2 + 2H2O + S
This sulfur is soluble in carbon disulfide and its insoluble in water. On heating or after some time it is converted into rhombic sulfur. It is also used in making medicines.
Uses Of Sulfur
(i.) Sulfur is used extensively in the industrial production of sulfuric acid.
(ii.) It is used in making gunpowder and matchmak.
Atomic number 16, Atomic weight 32, Electronic structure 1s22s22p63s23p4. valency +2, +4 and +6 and 2 in some compounds.
Sulfur has been known since ancient time. Sulfur come out with lava when the volcano bursts. Sulfur compounds are found in many springs and wells / stepwells.
Ancient Indian physicians used sulfur make various medicines. The properties of copper are destroyed when heated with sulfur.
A scientist named Lavoisier called is an element based on the study of its properties. Sulfur is found in free from in nature and various compounds.
Sulfur Allotropy
Allotropism-
Two or more forms of an element that exhibit differences in structure and other physical properties from each other but possess similar chemical properties are called as allotropes of that element. This properties of elements is called allotroopism.
Crystalline sulfur
(i) Rhombic Sulfur-
This form of sulfur is also known as alpha sulfur. This form sulfur is very stable at normal temperatures. It is insoluble in water but soluble in carbon disulfide. On heating it at 368.6 K (95.6' C), it is converted into another unconformable, monoclinic sulfur.
(ii.) Mono-clinic Sulfur-
This is also called beta sulfur. It occurs as a needle-shaped crystal. Therefore, it is also called cone sulfur, it is insoluble in the water and soluble in carbon disulfide. This alkali of sulfur is stable at temperatures above 368.6 K. At low temperatures, it converts to (alpha) sulfur. Both forms of sulfur coexist at 368.6 K. This temperatures is called transition temperature.
There are many elements that are different from metals in physical and chemical properties. called non- metals. For example carbon, oxygen, hydrogen, nitrogen, sulfur, etc. Nonmetals are also called electrically negative elements. Nonmetal make anion.
Properties of Non- Metals
(i.) Generally these are brittle, So its sheets or wires cannot be made.
(ii.) They do not have any special shine, but iodine is a shiny nonmetal.
(iii.) Its melting point are low but the melting point of diamond and graphite it very high, about 3000' C.
(iv.) They are often non-conductors of heat and electricity but graphite is a good conductor of electricity and heat.
(v.) It dose not contain free electron. The outermost orbit of their atom often has 5, 6 or 7 electrons.
(vi.) Non-metal oxides are acidic.
(vii.) Those substance which are made up of the some element, but their structure and composition are different, are called allotropic.
The method of extraction of pure metal from impure or raw metal proper conditions is called refining of the metal. Several methods are used to obtain metals of high purity. These are as follows.
Distillation-
Zn, Cd, Hg metals are treated by this method because they are low boiling point metals.
Electrolytic Refining-
Copper, silver, gold, aluminum and lead metal are treated by this method, anode of impure metal, and cathode of metal are made.
Zone Refining-
This method is based in the principle that the solubility of impurities is higher in the molten state than in the solid state of the metal. This metal is useful in obtaining very high purity semiconductors and other highly pure metals such as germanium, silic, boron, gallium and indium.
Vapour Phase Refining-
In this method, the metal is converted in to a voltatile compound. Thereafter, it is decomposed to obtain pure metal. Example Mode process It used for nickel.
Von-Arkell Method-
It is used for zirconium and titanium.
Chromatographic Method-
This method is based on the principle that absorption of different components of a mixture is different at the absorbent. Purification of elements found in small quantities is done in this method.
One-grinding-concentration, decantation, filling smelting, reduction of metal oxide, metal refining and pure metal recovery.
Extraction of modified from concentrated ores
Separation of metal from crude ores takes place in the following three main terms.
Change in oxide
This is achieved by the following two processes.
Calcination-
The process of heating an ore from its melting point to a lower temperature sequence in absence or air is called dislocation. Metal crbonates, disposes, hydroxides and oxides.
Roasting-
The process of heating the ore below its melting point in the presence of air is called Roasting. this is only for sulfide ores.
Reduction of Oxide in Metal-
Reduction of oxide in metal is done as follows-
Smelting-
It is reduction by carbon or its oxides. Reduction of metals located in the middle of the activation range is done by this method.
The process of heating the ore by mixing it with coke and sulfur at a temperature above its melting point is called effluent. Oxides of metals like lead, iron, tin, zinc etc. are reduced by this method. This method is used for smelting the entire mixture and reducing the metal oxides to the metal. Examples- PbO + C →2Pb(molten lead) + CO2
Aluminothermic Process-
Oxides of metals like chromium, manganese etc. are reduced by aluminum.
Auto-Reduction-
Metals falling below the activation range are much less active. Only by heating of oxides of these metals, metal can be obtained. Example- Copper, mercury, lead are reduced by this method.
Electrolytic Method-
This method is used for metals at the top of the activation range such as sodium, calcium, aluminum. By this method their oxides are reduced to metal. Sodium is obtained as a result of the decomposition of sodium chloride.
Sodium is 2.27% in the crust. Sodium is always found in the combined state due to high reactivity. The extraction of sodium metal is done by the electrolysis of dissolved sodium hydroxide by the Kastner method or by the electrical decomposition of dissolved by the down method.
Properties of Sodium-
It is a soft soft silver-like white metal that can be cut with a knife.
It is a highly functional metal. That is, it reacts with moist air to make sodium oxide (Na2 o) and it reacts with water to make sodium hydroxide (NaOH) and hydrogen gas.
It is soluble in Benzene.
It reacts with ammonia to make sodamide (NaNH2), and reacts with acid to make corresponding salts hydrogen and alcohol to form sodium alkoxide (NaOH) and hydrogen gas.
Uses of Sodium-
Sodium bicarbonate is uses as a medicine, to remove stomach acidity, to make baking soda, and in fair extinguishers.
When the salt is left in the open air, it absorbs moisture from the air which in transpire.
1. Sodium Chloride (NaCl)-Common Salt
Sodium chloride is obtained from the evaporation of water from sea or saline likes. Sodium chloride obtained from this salt water evaporation contains impurities of magnesium and potassium. In a saturated solution of this impure salt, pure sodium chloride is obtained by flowing HCl gas. It is Soluble in water.
Use
(i.) It is an essential part of our daily diet.
(ii.) Many industrial compounds of importance are obtained from it.
(iii.) It forms a coagulation mixture.
(iv.) It is used in the preservation of food items like meat, fish, butter etc.
(v.) Used to precipitate soap solution.
2. Sodium Carbonate (Na₂CO₃)
It is a white crystalline soda. The formula for washing soda is Na₂CO₃, 10H2O and anhydrous sodium carbonate is called soda ash. Its aqueous solution is alkaline.
Use
(i.) In the industrial production of glass, sodium silicate, paper, borax, hypo, baking powder.
(ii.) In washing clothes.
(iii.) In making "melting mixture" The melting mixture is a mixture of sodium carbonate and potassium carbonate.
Metals are electrically positive in nature, and have a tendency to give up electrons and form cations. Therefore, those metals react quickly non-metals oxygen, hydrogen, chlorine, sulfur etc.
Reaction of Metals with Oxygen-
All metals react with oxygen to form a metal oxides. For example aluminum oxide, reacting with aluminum, reacts with copper to produce copper oxide Metal oxides are insoluble in water.
Reaction of Metals with Water-
Metals like sodium, potassium and magnesium react with water to form metal hydroxides and produce hydrogen.
Reaction of Metals with Acid-
Metals react with dilute acid to produce the corresponding salts and hydrogen gases.
Reaction of Metals with Solution of other Metal salts-
Reactive metal displaces less reactive metal from its solution or dissolved state of its compound.
Color of Metal Flames-
Alkaline metals and their salts produce characteristic colors in the flame.
These are three type of elements- Metals, Non-metals and Metalloids. More then 90 of the presently known elements exhibit metallic properties. Along with many metals, these compounds are also very important in our lives. Calcium is present in bones. iron in the blood and magnesium in the center of a compound called chlorophyll, which is the cause of greening of plants.
The characteristic properties of metals are different from non-metals. Metals are on the left and center of the periodic tables.
All the element of S block, p block, d block and f block except hydrogen are metal while non-metal and located on the right side. They can be mounted on the right side. they can be mounted on a step. Elements on the stairs (Si, Ge, As, Sb and Te) have properties of both metals and non-metals which are called sub-metals.
Major among the non-metallic elements are hydrogen, boron, carbon, silicon, nitrogen, phosphorus, oxygen, sulfur, halogen and inert gases.
Metal
Elements that have a tendency to give up electrons and form cations are called metals. Gold, Silver, lead, iron, mercury etc. are some example of metal.
General Properties of Metals
The properties of metals can be divided into two part physical properties and chemical properties.
Physical Properties of Metals
Malleability
Malleability is the conversion of the metal into a thin layer on hammer beating.
Ductility
Ductility is the stretching of metals into thin wire.
Thermal Conductivity
All metals are conductors of heat. The best metal in conductivity is silver and the lowest conductive metal is lead.
Electric Conductivity
High electrical conductivity is indicated by metal. The best electrical conductivity is represented by silver and copper, second place is gold, aluminum and tungsten. Mercury and iron exhibit greater resistance to electric current.
Melting point and Boiling point
The melting point and boiling point of metal are high.
Density
The density of metal is higher then water Osmium is the heaviest metal.
Hardness
Generally, metals are hard but alkaline metal like sodium, potassium and lithium are soft. It is possible to cut them with a knife.
Metallic Lusture
Generally, all metal are shiny. Their luster is called metallic lustre.
Sonorous
Sound is usually product by beating metals. This property of metals is used in making temple bells, school bells etc.
