Understand the Chemical Properties of Metals. Click on the link to Watch the VIDEO explanation:
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All elements discovered by men have been systematically organised into periodic table. Most of these are metals. Name of some are highlighted. We see only a few metals in pure form. Most of them do not exist in pure or native form. They are highly reactive so react with other elements and disguised. Why are they highly reactive. Metals are all electropositive in nature. This means they tend to lose electron and get positive charge. So they act as strong reducing agent and undergo chemical reaction in their electropositive state. Metals have valence range of 1 to 3. This means they can lose one two or three electrons from their valence shell. All metals are solid at room temperature and reacts easily with gases and liquids. Gases like hydrogen, oxygen and chlorine and liquid like water acid and salt reacts easily with metal. Reactivity of metals with gases. When surfaces of metals like sodium or calcium are exposed to air, after sometime a white coat of oxide forms. Metals react with oxygen in air to form oxide. Sodium forms sodium oxide and calcium forms calcium oxide. When these oxides dissolve in water they form their hydroxides. So such oxide are basic in nature. Colourless phenolphthalein turns pink in hydroxide solution. This is a test of basic nature of hydroxide. Similarly Hydrogen reacts with metal to form Hydrides and chlorine to form chlorides. The reactivity of water varies with nature of metals. Metals that reacts with water can also reacts with acids. For example acids like HCl and H2SO4 reacts with metals to form respective chloride and sulphate salts. A more reactive metal displaces a less reactive metal from its salt solution and takes its place. Zinc is more reactive than copper. So when zinc is placed in copper solution it replaces copper to form zinc sulphate and copper metal is set free.
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All elements discovered by men have been systematically organised into periodic table. Most of these are metals. Name of some are highlighted. We see only a few metals in pure form. Most of them do not exist in pure or native form. They are highly reactive so react with other elements and disguised. Why are they highly reactive. Metals are all electropositive in nature. This means they tend to lose electron and get positive charge. So they act as strong reducing agent and undergo chemical reaction in their electropositive state. Metals have valence range of 1 to 3. This means they can lose one two or three electrons from their valence shell. All metals are solid at room temperature and reacts easily with gases and liquids. Gases like hydrogen, oxygen and chlorine and liquid like water acid and salt reacts easily with metal. Reactivity of metals with gases. When surfaces of metals like sodium or calcium are exposed to air, after sometime a white coat of oxide forms. Metals react with oxygen in air to form oxide. Sodium forms sodium oxide and calcium forms calcium oxide. When these oxides dissolve in water they form their hydroxides. So such oxide are basic in nature. Colourless phenolphthalein turns pink in hydroxide solution. This is a test of basic nature of hydroxide. Similarly Hydrogen reacts with metal to form Hydrides and chlorine to form chlorides. The reactivity of water varies with nature of metals. Metals that reacts with water can also reacts with acids. For example acids like HCl and H2SO4 reacts with metals to form respective chloride and sulphate salts. A more reactive metal displaces a less reactive metal from its salt solution and takes its place. Zinc is more reactive than copper. So when zinc is placed in copper solution it replaces copper to form zinc sulphate and copper metal is set free.
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