Chemical Properties Of Metals And Nonmetals

Chemical Properties Of Metals And Nonmetals

Chemical properties of metals and non-metals can be divided into five categories: reaction with oxygen, reaction with water, reaction with acids, reaction with bases, and displacement reactions.

Reaction with Oxygen

Metals: Most metals combine with oxygen to form metal oxides.
Chemical Properties Of Metals And Nonmetals 1

  • Sodium reacts vigorously with the oxygen present in air to form sodium oxide. As a result, it catches fire if left in open. It is, therefore, kept immersed in kerosene.
    Chemical Properties Of Metals And Nonmetals 2
  • Magnesium, on heating, burns in air (oxygen) with a dazzling white light to form magnesium oxide.
    Chemical Properties Of Metals And Nonmetals 3
    The metallic oxides formed are basic in nature and turn red litmus solution blue.

Non-metals: Non-metals like carbon, sulphur, and phosphorus react with oxygen to form non-metallic oxides. These oxides are also called acidic oxides as they form acids when dissolved in water.
Chemical Properties Of Metals And Nonmetals 4

  • Carbon burns in air (oxygen) to form carbon dioxide.
    Chemical Properties Of Metals And Nonmetals 5
  • Sulphur burns in air (oxygen) to form a pungent (i.e., having a strong smell), suffocating gas called sulphur dioxide.
    Chemical Properties Of Metals And Nonmetals 6
  • These oxides dissolve in water to form acids.
    Chemical Properties Of Metals And Nonmetals 7

Activity 

Aim: To synthesize a non-metallic oxide and test its solution using litmus paper.
Materials needed: Sulphur, a long-handled spoon or a deflagrating spoon, burner, water, gas jar with a lid, and blue litmus paper.
Method:

  1. Take a small amount of sulphur in the long-handled spoon/ deflagrating spoon and heat it over the flame of a burner.
  2. When sulphur starts burning, lower the spoon into the gas jar. Cover the jar partly with the lid while the sulphur is still burning.
  3. The jar will be filled with sulphur dioxide gas. Remove the spoon and cover the gas jar with a lid.
  4. Add 20 ml water to the gas jar and test this solution with blue litmus paper.

Chemical Properties Of Metals And Nonmetals 8Observation: Blue litmus paper turns red, indicating that the solution is acidic.
Conclusion: Water dissolves the gas (sulphur dioxide) to form an acid (sulphurous acid), which turns blue litmus red.
Note: Adult supervision required.

Reaction with Water

Metals Most metals react with water to produce a metal hydroxide or metal oxide and hydrogen gas.
Chemical Properties Of Metals And Nonmetals 9

  • Sodium reacts violently with cold water to form sodium hydroxide along with hydrogen gas. A large amount of heat is evolved in this reaction, which results in hydrogen catching fire.
    Chemical Properties Of Metals And Nonmetals 10
  • Metals like copper, silver, and gold do not react with water under any conditions.

Non-metals: Non-metals do not react with water.

Corrosion
Iron and many other metals react with oxygen and moisture present in the atmosphere. This phenomenon is called corrosion. The process of slow eating away of a metal due to the attack of atmospheric gases and moisture on its surface is called corrosion.

  • Iron reacts with oxygen and moisture present in the atmosphere to form a brown, flaky substance called rust. Rusting of iron is an undesirable reaction because the layer of rust formed falls off, exposing the metal to further rusting. As a result, iron objects become weak with the passage of time.
  • Copper objects get coated with a green substance called basic copper carbonate with the passage of time. This green substance is formed due to the reaction of copper with carbon dioxide and moisture present in the atmosphere.

Chemical Properties Of Metals And Nonmetals 11

  • Silver objects become blackened and lose their sheen with the passage of time. This happens due to the reaction of silver with hydrogen sulphide gas present in the atmosphere.

Chemical Properties Of Metals And Nonmetals 12

Reaction with Acids

Metals When a metal reacts with an acid, a salt and hydrogen gas are produced.
Salts are compounds formed when a metal replaces hydrogen in an acid. Different acids and metals react to form different salts.
Chemical Properties Of Metals And Nonmetals 13

  • Zinc reacts with sulphuric acid to form zinc sulphate and hydrogen gas.
    Chemical Properties Of Metals And Nonmetals 14
  • Magnesium reacts with sulphuric acid to form magnesium sulphate and hydrogen gas.
    Chemical Properties Of Metals And Nonmetals 15
  • Aluminium reacts with hydrochloric acid to form aluminium chloride and hydrogen gas.
    Chemical Properties Of Metals And Nonmetals 16

With some metals, the reaction is very fast and vigorous, while with others it may be slow. Some metals do not react with acids at all.
Non-metals: Generally, non-metals do not react with acids.

Activity

Aim: To show that hydrogen is produced when magnesium reacts with dilute sulphuric acid
Materials needed: Magnesium ribbon, dilute sulphuric acid, test tube, dropper, and a matchstick
Method:

  1. Take a piece of magnesium ribbon in the test tube.
  2. Using a dropper, carefully add a few drops of dilute sulphuric acid from the sides of the test tube.
  3. Bring a burning matchstick near the mouth of the test tube.

Observation: Bringing a burning matchstick nearthe mouth ofthe test tube produces a ‘pop’ sound. Conclusion: The gas produced in the reaction is hydrogen.
Note: Adult supervision required.

Reaction with Bases

Metals: Most metals do not react with bases. Only a few, like aluminium, zinc, and lead, react with solutions of strong bases like sodium hydroxide to produce a compound of that metal and hydrogen gas. You could perform the above activity using small pieces of zinc and sodium hydroxide solution (instead of magnesium ribbon and dilute sulphuric acid) to test that hydrogen is evolved in the reaction.
Non-metals: The reactions of non-metals with bases are complex. You will learn about them in higher classes.

Displacement Reactions

Chemical Properties Of Metals And Nonmetals 17 In a displacement reaction, a metal reacts with a salt solution and ‘displaces’ (or replaces) the metal present in it. Displacement reactions are explained on the basis of the activity series of metals.

The activity series of metals is a list of common metals arranged in the decreasing order of reactivity. This means that a metal which is placed higher in the activity series is more reactive than those placed below it. The activity series of metals is shown in figure. You can predict whether or not a displacement reaction will take place by looking at the activity series. A metal will only react with a salt solution if it is placed higher in the activity series than the metal in the salt. For example, iron, which is placed higher in the activity series than copper, reacts with copper sulphate solution. Copper, however, does not react with iron sulphate as it is less reactive than iron. Some more examples are discussed below.

  • Silver does not react with zinc sulphate.Chemical Properties Of Metals And Nonmetals 18
  • Zinc reacts with copper sulphate to form zinc sulphate and copper.
    Chemical Properties Of Metals And Nonmetals 19
  • Silver does not react with copper sulphate.Chemical Properties Of Metals And Nonmetals 20

From the above reactions, we can conclude that the order of reactivity of zinc, copper, and silver is: Zn > Cu > Ag (i.e., zinc is the most reactive of the three and silver, the least reactive).

Activity

Aim: To prove that iron is more reactive than copper.
Materials needed: Iron filings, copper turnings, copper sulphate solution, iron sulphate solution, test tubes, and a dropper.
Method:

  1. Take some iron filings in a test tube and add some copper sulphate solution with the help of a dropper (test tube A).
  2. Take some copper turnings in a test tube and add some iron sulphate solution with the help of a dropper (test tube B).

Chemical Properties Of Metals And Nonmetals 21Observation: In test tube A, iron filings turn brown due to the deposition of copper and the solution turns pale green due to the formation of iron sulphate solution. No reaction is observed in test tube B.
Conclusion: Iron is more reactive than copper as it displaces copper from copper sulphate solution.

Physical Properties Of Metals And Nonmetals

Physical Properties Of Metals And Nonmetals

Different elements have different properties. These properties can make these elements suitable for various purposes. Elements can be classified into two broad categories: metals and non-metals. Aluminium and mercury are examples of metals. Diamond and oxygen are examples of non-metals.
Let us learn about physical and chemical properties of metals and non-metals.
Physical properties include physical state, lustre, colour, hardness, malleability, ductility, thermal conductivity, electrical conductivity, and sonority.

Physical State

Metals: Almost all metals are solids at room temperature. Mercury, gallium, francium, caesium, and rubidium are the only metals known to occur in a liquid state at or near room temperature.
Non-metals: Almost all non-metals are solids or gases at room temperature. Bromine is the only non-metal that exists as a liquid at room temperature.

Lustre

Metals: ‘Glitter’ or a shiny surface is a property of most metals. This is because metals can be polished. This property is called lustre. Because of their ability to shine and reflect light, metals like gold, silver, and platinum are used for making jewellery and other decorative articles.
Non-metals: Almost all non-metals have a dull surface. As most of them occur as powders and gases, they cannot be polished like metals. Graphite and iodine do show some lustre.

Physical Properties Of Metals And Nonmetals 1
metals with lustre

Colour

Metals: Most metals are white or silvery-grey. There are, however, a few exceptions. For example, gold is yellow and copper is reddish-brown.
Non-metals: Some non-metals are colourless while some are coloured. For example, chlorine is a greenish-yellow gas, bromine is a brown liquid, iodine is a violet solid, and oxygen and nitrogen are colourless gases.

Hardness

Metals: Most metals are hard but some (e.g., sodium and potassium) are so soft that they can be cut with a knife.
Non-metals: Non-metals are generally soft. Diamond is an exception. It is the hardest substance known.

Malleability

Metals: Most metals can be beaten into thin sheets or foils. The property by virtue of which metals can be beaten into thin sheets is called malleability. Gold and silver are the most malleable metals known. This is what helps jewellery designers create intricately carved bangles, chains, and decorative articles in gold and silver. Other metals that can be beaten into sheets include aluminium, iron, copper, and tin.
Non-metals: Non-metals are brittle and cannot be beaten into sheets or foils.

Physical Properties Of Metals And Nonmetals 2Physical Properties Of Metals And Nonmetals 2

Activity

Aim: To show that metals are malleable and non-metals are brittle.
Materials needed: Small samples of easily available metals (e.g., aluminium wire, iron nail, copper wire, etc.) and non-metals (e.g., graphite and charcoal) and a hammer.
Method: Pound the objects one by one with the help of the hammer.
Observation: Metal objects get flattened upon hammering while non-metals break.
Conclusion: Metals are malleable whereas non-metals are brittle.
Note: Adult supervision required.

Ductility

Metals: Most metals can easily be drawn into thin wires, which have a wide range of applications. The property by virtue of which metals can be drawn into thin wires is called ductility. Gold and silver are two of the most ductile metals known. Other metals that can be drawn into wires include copper, aluminium, and tungsten.
Non-metals: Non-metals are brittle and cannot be drawn into wires.

Thermal Conductivity

Metals: Metals are good conductors of heat and are, therefore, used for making cooking utensils. Silver is the best conductor of heat followed by copper.
Non-metals: Non-metals are generally poor conductors of heat. Diamond, which is a good conductor of heat, is an exception.

Electrical Conductivity

Metals: Metals are good conductors of electricity and are, therefore, used for making electrical wires and cables.
Non-metals: Non-metals are generally poor conductors of electricity. Graphite, which is a good conductor of electricity, is an exception.

Activity

Aim: To show that metals and graphite are good conductors of electricity and other non-metals are poor conductors.
Materials needed: Small samples of easily available metals (e.g., aluminium wire, iron nail, copper wire, etc.) and non-metals (e.g., graphite and charcoal), a copper wire cut into three pieces, a pencil cell, and a 1.5-volt bulb.
Method:
1. Set up the apparatus as shown in the figure.
2. Connect the two free ends (A and B) of the copper wire to the objects, one by one.
Physical Properties Of Metals And Nonmetals 3
Observation: The bulb glows when metals and graphite are connected to the free ends of the copper wire, but not for other non-metals.
Conclusion: Metals and graphite are good conductors of electricity whereas non-metals are poor conductors.

Sonority

Metals: When metal pipes strike each other, they produce a ringing sound. The property by virtue of which metal objects produce a ringing sound when struck with a hard object is called sonority. Objects like wind chimes and bells make use of this property of metals.
Non-metals: Non-metals produce a dull sound when struck with a hard object.