Notes On Comparison of Metals and Non-Metals - ICSE Class 10 Chemistry
Comparison of metals and non-metals Metals are elements that have a tendency to lose electrons and form positively charged ions or cations. Example: Sodium has an electronic configuration of 2, 8, 1. During a chemical reaction sodium can lose an electron to a non metal like chlorine to form a sodium ion that has an electronic configuration of 2, 8. Physical properties of metals Physical state All metals are solids at room temperature, for example, iron and copper. The one exception is mercury, which is a liquid. Lustrous nature All metals are lustrous. Metal surfaces shine when they are freshly cut. Example: Gold and silver are popularly used for making jewellery because of their lustrous nature. Density Metals have high densities and, therefore, tend to sink in water. Example: Tin and lead sink in water. Exceptions to this rule are lithium, sodium and potassium. The density of these elements is lower than that of water and hence they do not sink. Malleability Metals are highly malleable, and can be beaten into thin sheets. Example: Aluminium and zinc can be rolled into thin sheets. This property makes them suitable for use in various industries like construction and manufacturing. Ductility Metals are highly ductile and can be drawn into wires. For example, copper and silver can be drawn into thin wires. Conductivity Metals are good conductors of heat and electricity. Copper wires are commonly used in electric cables because of this property. Melting point Metals have high melting points. Example: Tungsten has a high melting point, due to which it is used in bulb filaments. Mercury is an exception to this property, since it has a low melting point. Conversely non metals are elements that have a tendency to accept electrons to form negatively charged ions or anions. Example: Chlorine has an electronic configuration of 2,8,7. During a chemical reaction, chlorine can accept an electron from a metal like sodium to form a chloride ion. A chloride ion has an electronic configuration of 2,8,8. Physical properties of non-metals Physical state Non-metals exist as solids, liquids and gases. Example: Silicon and carbon are solids; bromine is a liquid; chlorine, fluorine and oxygen are gases. Lustrous nature Non-metals are non-lustrous and have a dull appearance in nature. Density Most of the non-metals have very low density. Example: Oxygen and nitrogen are lighter than air. Exception is diamond, a form of carbon. Diamond is one of the strongest known substances. Non-metals are not malleable and ductile. Non-metals are bad conductors of heat and electricity. Exception is graphite, a form of carbon which is a good conductor of electricity. Non-metals have low melting and boiling points. Example: Sulphur and Phosphorus have low melting and boiling points. Reactivity towards oxygen Most of the metals combine with Oxygen to form basic metal oxides. Burning a strip of Magnesium Magnesium will burn in oxygen to form magnesium oxide. 2Mg + O2 → 2MgO Magnesium oxide dissolves in water to form magnesium hydroxide, which is basic in nature. MgO + H2O → Mg(OH)2 Exceptions: Aluminium oxide and zinc oxide exhibits both acidic and basic properties. This type of acids are known as amphoteric oxides. Ingeneral metal oxides are insoluble in water. But few of them dissolve in water to produce alkalis. Alkalis Water soluble bases are called alkalis. Sodium oxide and potassium oxide dissolved in water and form sodiumhydroxide and potassium hydroxide respectively. Na2O + H2O → 2NaOH K2O + H2O → 2KOH Metals differ in their rectivity towards oxygen. Metals like Na, K are highly reactive. They catch fire very easily when they expose to air. Hence to protect their from accidental fire they are immersed in kerosene oil. At ordinary temperature the surfaces of some metals like Mg, Al, Zn, Pb are coverd with thin layer of oxide. This oxide layer prevents the further oxidation of metal. Iron does not burn on heating.Copper also does not burn on heating. Gold and silver do not reacts with oxygen even at high temperature. Anodising The process of formation of a thick oxide layer of aluminium is called anodising. When exposed to air aluminium develops a thin oxide layer. anodising is done to improve the resistence of aluminium to corrosion. During anodising a clean aluminum article is taken as an anode. This is electrolysed by using dil. Sulphuric acid. During the process of electrolysis the oxygen gas released at the anode makes the thick protective oxide layer. This oxide layer can be died easily which gives aluminium articles an attractive tarnish. Reaction of non-metals with oxygen Non-metals reacts with oxygen to form oxides which are either acidic or neutral in nature. Example: Sulphur reacts with oxygen to form sulphur dioxide which is acidic in nature S + O2 → SO2 Nitrogen reacts with limited supply oxygen to form nitric oxide which is a neutral oxide in nature. N2 + O2 → 2NO Non-metal oxides dissolves in water to form acidic solutions. Example: Sulphur dioxide dissolves in water to form sulphurous acid. SO2 + H2O → H2SO3 Reactivity towards water While moving down in the activity series the reactivity towards water decreases. Potassium, sodium and calcium can reacts vigorously even with cold water with the liberation of hydrogen gas. K + H2O → KOH + H2 Na + H2O → NaOH + H2 Ca + H2O → Ca(OH)2 + H2 Magnesium reacts very slowly with cold water but can reacts vigorously with hot water to produce hydrogen gas Mg + H2O → MgO + H2 Metals like aluminium, zinc and iron does not reacts with cold water or warm water but can reacts with hot steam. 2Al + H2O → Al2O3 + H2 Zn + H2O → ZnO + H2 3Fe + H2O → Fe3O4 + H2 Reaction of Non- metals with water Non- metals do not react with water. Reactivity towards mineral acids The metals which are present above hydrogen in the reactivity series can reduce hydrogen ions from the acids like HCl and H2SO4. Reactivity decreases on moving down the group in the series. Potassium, sodium reacts vigorously with dilute acids to liberate hydrogen gas. K + 2HCl → 2KCl + H2 Na + 2HCl → 2NaCl + H2 Calcium, magnesium also reacts vigorously but slowly with acids libearating hydrogen gas. Ca + 2HCl → CaCl2 + H2 Mg + 2HCl → MgCl2 + H2 Copper does not react with dilute hydrochloric acid even on heating, but it reacts with dilute sulphuric acid on heating. Cu + dil.H2SO4 (heating)  → CuSO4 + H2 Reaction of non- metals with acids Generally non- metals do not react with acids. Reaction with bases Only few metals can react with strong bases to metal salts and releases hydrogen gas. Examples: Aluminium, zinc and lead. Zinc metal reacts with sodium hydroxide to form sodium zincate and hydrogen gas. Zn + NaOH → NaZnO2 + H2 The reaction of non-metals with bases are complex. Displacement reactions The arrangement of metals in the decreasing order of their reactivity is known as activity series. In the activity series highly reactive metals placed at the top and least reactive metals placed at the bottom. Gold placed at bottom of the series is the least reactive among the metals and potassium placed at the top is the highly reactive metal.  Hydrogen is the non-metal included iin order to compare the reactivity of metals. The metal placed higher in the series can displace the other metal from its salt solution. Thus potassium can displace all other metals from their salt solutions. Example: Potassium can displace hydrogen from the acids. 2K + 2HCl →2KCl + H2 Metals of low reactivity cannot displace high reactive metals from their salts. For this reason oxides of highly reactive metals like magnesium and aluminium are not reduced easily either by hydrogen, carbon or carbon monoxide. Metals that are placed below copper do not rust easily because of their low reactivity.

#### Summary

Comparison of metals and non-metals Metals are elements that have a tendency to lose electrons and form positively charged ions or cations. Example: Sodium has an electronic configuration of 2, 8, 1. During a chemical reaction sodium can lose an electron to a non metal like chlorine to form a sodium ion that has an electronic configuration of 2, 8. Physical properties of metals Physical state All metals are solids at room temperature, for example, iron and copper. The one exception is mercury, which is a liquid. Lustrous nature All metals are lustrous. Metal surfaces shine when they are freshly cut. Example: Gold and silver are popularly used for making jewellery because of their lustrous nature. Density Metals have high densities and, therefore, tend to sink in water. Example: Tin and lead sink in water. Exceptions to this rule are lithium, sodium and potassium. The density of these elements is lower than that of water and hence they do not sink. Malleability Metals are highly malleable, and can be beaten into thin sheets. Example: Aluminium and zinc can be rolled into thin sheets. This property makes them suitable for use in various industries like construction and manufacturing. Ductility Metals are highly ductile and can be drawn into wires. For example, copper and silver can be drawn into thin wires. Conductivity Metals are good conductors of heat and electricity. Copper wires are commonly used in electric cables because of this property. Melting point Metals have high melting points. Example: Tungsten has a high melting point, due to which it is used in bulb filaments. Mercury is an exception to this property, since it has a low melting point. Conversely non metals are elements that have a tendency to accept electrons to form negatively charged ions or anions. Example: Chlorine has an electronic configuration of 2,8,7. During a chemical reaction, chlorine can accept an electron from a metal like sodium to form a chloride ion. A chloride ion has an electronic configuration of 2,8,8. Physical properties of non-metals Physical state Non-metals exist as solids, liquids and gases. Example: Silicon and carbon are solids; bromine is a liquid; chlorine, fluorine and oxygen are gases. Lustrous nature Non-metals are non-lustrous and have a dull appearance in nature. Density Most of the non-metals have very low density. Example: Oxygen and nitrogen are lighter than air. Exception is diamond, a form of carbon. Diamond is one of the strongest known substances. Non-metals are not malleable and ductile. Non-metals are bad conductors of heat and electricity. Exception is graphite, a form of carbon which is a good conductor of electricity. Non-metals have low melting and boiling points. Example: Sulphur and Phosphorus have low melting and boiling points. Reactivity towards oxygen Most of the metals combine with Oxygen to form basic metal oxides. Burning a strip of Magnesium Magnesium will burn in oxygen to form magnesium oxide. 2Mg + O2 → 2MgO Magnesium oxide dissolves in water to form magnesium hydroxide, which is basic in nature. MgO + H2O → Mg(OH)2 Exceptions: Aluminium oxide and zinc oxide exhibits both acidic and basic properties. This type of acids are known as amphoteric oxides. Ingeneral metal oxides are insoluble in water. But few of them dissolve in water to produce alkalis. Alkalis Water soluble bases are called alkalis. Sodium oxide and potassium oxide dissolved in water and form sodiumhydroxide and potassium hydroxide respectively. Na2O + H2O → 2NaOH K2O + H2O → 2KOH Metals differ in their rectivity towards oxygen. Metals like Na, K are highly reactive. They catch fire very easily when they expose to air. Hence to protect their from accidental fire they are immersed in kerosene oil. At ordinary temperature the surfaces of some metals like Mg, Al, Zn, Pb are coverd with thin layer of oxide. This oxide layer prevents the further oxidation of metal. Iron does not burn on heating.Copper also does not burn on heating. Gold and silver do not reacts with oxygen even at high temperature. Anodising The process of formation of a thick oxide layer of aluminium is called anodising. When exposed to air aluminium develops a thin oxide layer. anodising is done to improve the resistence of aluminium to corrosion. During anodising a clean aluminum article is taken as an anode. This is electrolysed by using dil. Sulphuric acid. During the process of electrolysis the oxygen gas released at the anode makes the thick protective oxide layer. This oxide layer can be died easily which gives aluminium articles an attractive tarnish. Reaction of non-metals with oxygen Non-metals reacts with oxygen to form oxides which are either acidic or neutral in nature. Example: Sulphur reacts with oxygen to form sulphur dioxide which is acidic in nature S + O2 → SO2 Nitrogen reacts with limited supply oxygen to form nitric oxide which is a neutral oxide in nature. N2 + O2 → 2NO Non-metal oxides dissolves in water to form acidic solutions. Example: Sulphur dioxide dissolves in water to form sulphurous acid. SO2 + H2O → H2SO3 Reactivity towards water While moving down in the activity series the reactivity towards water decreases. Potassium, sodium and calcium can reacts vigorously even with cold water with the liberation of hydrogen gas. K + H2O → KOH + H2 Na + H2O → NaOH + H2 Ca + H2O → Ca(OH)2 + H2 Magnesium reacts very slowly with cold water but can reacts vigorously with hot water to produce hydrogen gas Mg + H2O → MgO + H2 Metals like aluminium, zinc and iron does not reacts with cold water or warm water but can reacts with hot steam. 2Al + H2O → Al2O3 + H2 Zn + H2O → ZnO + H2 3Fe + H2O → Fe3O4 + H2 Reaction of Non- metals with water Non- metals do not react with water. Reactivity towards mineral acids The metals which are present above hydrogen in the reactivity series can reduce hydrogen ions from the acids like HCl and H2SO4. Reactivity decreases on moving down the group in the series. Potassium, sodium reacts vigorously with dilute acids to liberate hydrogen gas. K + 2HCl → 2KCl + H2 Na + 2HCl → 2NaCl + H2 Calcium, magnesium also reacts vigorously but slowly with acids libearating hydrogen gas. Ca + 2HCl → CaCl2 + H2 Mg + 2HCl → MgCl2 + H2 Copper does not react with dilute hydrochloric acid even on heating, but it reacts with dilute sulphuric acid on heating. Cu + dil.H2SO4 (heating)  → CuSO4 + H2 Reaction of non- metals with acids Generally non- metals do not react with acids. Reaction with bases Only few metals can react with strong bases to metal salts and releases hydrogen gas. Examples: Aluminium, zinc and lead. Zinc metal reacts with sodium hydroxide to form sodium zincate and hydrogen gas. Zn + NaOH → NaZnO2 + H2 The reaction of non-metals with bases are complex. Displacement reactions The arrangement of metals in the decreasing order of their reactivity is known as activity series. In the activity series highly reactive metals placed at the top and least reactive metals placed at the bottom. Gold placed at bottom of the series is the least reactive among the metals and potassium placed at the top is the highly reactive metal.  Hydrogen is the non-metal included iin order to compare the reactivity of metals. The metal placed higher in the series can displace the other metal from its salt solution. Thus potassium can displace all other metals from their salt solutions. Example: Potassium can displace hydrogen from the acids. 2K + 2HCl →2KCl + H2 Metals of low reactivity cannot displace high reactive metals from their salts. For this reason oxides of highly reactive metals like magnesium and aluminium are not reduced easily either by hydrogen, carbon or carbon monoxide. Metals that are placed below copper do not rust easily because of their low reactivity.

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