Ch.3 Metals and Non-Metals
Q. Define the following terms:
a. Malleability
b. Ductility
c. Sonority
d. Reactivity series.
d. Dilute nitric acid (dil. HNO₃) is a strong oxidizing agent and so it oxidizes the hydrogen gas produced to water i.e. H₂→H₂O and itself gets reduced to any of the nitrogen oxides..
e. Copper is the most ductile metal after gold and silver i.e. it can be easily drawn into wires. Also, copper is a good conductor of electricity.
f. Sodium (Na) tends to react vigorously with atmosphere oxygen and catch fire when exposed to air. Thus, in order to cut the supply of air and avoid accidental fires it is stored under kerosene.
g. Platinum, gold and silver are lustrous metals and also the least reactive elements so they do not react with oxygen even at high temperatures and thus they are used to make jewelry.
h. Aluminium is used to make cooking utensils since it develops a protective coating of aluminum oxide when exposed to air which prevents it from further oxidation and thus corrosion as well. Hence, it is used to make cooking utensils.
Q. What are the exceptions in the physical properties of metals and non-metals?
A. Metals:-
1. Mercury: does not exist as solid at room temperature
2 Caesium and Gallium: very low melting points
3. Lithium, Sodium and Potassium: very soft, can be cut with a knife
Non-Metals:-
1. Bromine: present in liquid state at room temperature
2. Iodine: lustrous
3. Carbon: shows allotropy
Q. What are amphoteric oxides? Give examples.
A. Some oxides show acidic as well as basic behaviour. These oxides are known as amphoteric oxides. For example, aluminium oxide (Al₂O₃) and zinc oxide (ZnO).
Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
Q. Which non-metal exists in liquid state?
A. Bromine
Q. What is a covalent bond?
A. A covalent bond is a bond formed by sharing of electrons between two atoms to get a stable electron arrangement. e.g. O₂, H₂O, C₂H₄ etc.
Q. What type of bonds are present in hydrogen chloride and oxygen?
A. Covalent bonds
Q. What is an ionic bond?
A. An ionic bond is a bond formed by the transfer of electrons from one atom to another. e.g. NaCl, FeSO₄, MgCl₂ etc.
Q. a) What are noble gases? What is the characteristic of the electronic configuration of noble gases?
b) What is the cause of chemical bonding (/combination) of atoms of elements?
A. a) The elements present in the group 18 of the periodic table are known as noble gases. These are the elements which are unreactive and do not react with other elements to form compounds. The characteristic of electronic configuration of noble gases is that their octet (/duplet) is completely filled i.e. they have 8 electrons in their valence shell (or 2 in case of Helium which only has the K shell) thus making them stable and unreactive.
b) The atoms combine to complete the octet (or duplet) of their valence shell giving them an inert gas electron configuration and thus making them more stable.
Q. Give an example of a metal which
i) is a liquid at room temperature
ii) can be easily cut with a knife
iii) is the best conductor of heat
iv) is a poor conductor of heat
A.
i) Bromine
ii) Sodium
iii) Silver
iv) Lead
Q. i) Which gas is produced when dilute hydrochloric acid is added to a reactive metal?
ii) Write the chemical equation when iron reacts with dilute H₂SO₄?
A. i) Hydrogen
ii) Fe(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂↑
Q. Write the steps to obtain a metal from its ore in brief. What is this process called?
A. The process to obtain a metal from its ore is called extraction. Broadly, it involves 3 main steps:
i) Concentration (/Enrichment) of ore: Ore is impure as it contains a lot of unwanted material like sand and rocks called gangue. Thus it is necessary to remove these impurities to obtain the metal. This process of removing these impurities is called concentration (/enrichment) of ore.
ii) Taking out the metal from the concentrated ore: Highly reactive metals (K, Na, Ca, Mg, Al) are separated from their ore by the electrolysis of their molten chloride or oxides. Moderately reactive metals (Zn-Hg) are extracted by reducing their oxides with carbon or with a metal of higher reactivity. Some metals which occur in carbonate or oxide forms are first converted into their oxide forms and then reduced. Less reactive metals (Cu, Hg, Ag, Au, Pt) are found in their native states. Cu and Hg are found in sulphide forms and can be extracted by simply heating them in the presence of oxygen.
iii) Refining of metals: The metals which are taken out still contain some impurities. The process of purifying impure metals is called refining. Metals are mostly refined through electrolysis i.e electrolytic refining.
Q. What is aqua regia?
A. Aqua regia, (Latin for ‘royal water’) is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1. It can dissolve gold, even though neither of these acids can do so alone. Aqua regia is a highly corrosive, fuming liquid. It is one of the few reagents that is able to dissolve gold and platinum.
Q. Differentiate between:
a. Mineral and Ore
b. Calcination and Roasting
c. Corrosion and Rusting
a.
a. Malleability
b. Ductility
c. Sonority
d. Reactivity series.
d. Dilute nitric acid (dil. HNO₃) is a strong oxidizing agent and so it oxidizes the hydrogen gas produced to water i.e. H₂→H₂O and itself gets reduced to any of the nitrogen oxides..
e. Copper is the most ductile metal after gold and silver i.e. it can be easily drawn into wires. Also, copper is a good conductor of electricity.
f. Sodium (Na) tends to react vigorously with atmosphere oxygen and catch fire when exposed to air. Thus, in order to cut the supply of air and avoid accidental fires it is stored under kerosene.
g. Platinum, gold and silver are lustrous metals and also the least reactive elements so they do not react with oxygen even at high temperatures and thus they are used to make jewelry.
h. Aluminium is used to make cooking utensils since it develops a protective coating of aluminum oxide when exposed to air which prevents it from further oxidation and thus corrosion as well. Hence, it is used to make cooking utensils.
Q. What are the exceptions in the physical properties of metals and non-metals?
A. Metals:-
1. Mercury: does not exist as solid at room temperature
2 Caesium and Gallium: very low melting points
3. Lithium, Sodium and Potassium: very soft, can be cut with a knife
Non-Metals:-
1. Bromine: present in liquid state at room temperature
2. Iodine: lustrous
3. Carbon: shows allotropy
Q. What are amphoteric oxides? Give examples.
A. Some oxides show acidic as well as basic behaviour. These oxides are known as amphoteric oxides. For example, aluminium oxide (Al₂O₃) and zinc oxide (ZnO).
Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
Q. Which non-metal exists in liquid state?
A. Bromine
Q. What is a covalent bond?
A. A covalent bond is a bond formed by sharing of electrons between two atoms to get a stable electron arrangement. e.g. O₂, H₂O, C₂H₄ etc.
Q. What type of bonds are present in hydrogen chloride and oxygen?
A. Covalent bonds
Q. What is an ionic bond?
A. An ionic bond is a bond formed by the transfer of electrons from one atom to another. e.g. NaCl, FeSO₄, MgCl₂ etc.
Q. a) What are noble gases? What is the characteristic of the electronic configuration of noble gases?
b) What is the cause of chemical bonding (/combination) of atoms of elements?
A. a) The elements present in the group 18 of the periodic table are known as noble gases. These are the elements which are unreactive and do not react with other elements to form compounds. The characteristic of electronic configuration of noble gases is that their octet (/duplet) is completely filled i.e. they have 8 electrons in their valence shell (or 2 in case of Helium which only has the K shell) thus making them stable and unreactive.
b) The atoms combine to complete the octet (or duplet) of their valence shell giving them an inert gas electron configuration and thus making them more stable.
Q. Give an example of a metal which
i) is a liquid at room temperature
ii) can be easily cut with a knife
iii) is the best conductor of heat
iv) is a poor conductor of heat
A.
i) Bromine
ii) Sodium
iii) Silver
iv) Lead
Q. i) Which gas is produced when dilute hydrochloric acid is added to a reactive metal?
ii) Write the chemical equation when iron reacts with dilute H₂SO₄?
A. i) Hydrogen
ii) Fe(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂↑
Q. Write the steps to obtain a metal from its ore in brief. What is this process called?
A. The process to obtain a metal from its ore is called extraction. Broadly, it involves 3 main steps:
i) Concentration (/Enrichment) of ore: Ore is impure as it contains a lot of unwanted material like sand and rocks called gangue. Thus it is necessary to remove these impurities to obtain the metal. This process of removing these impurities is called concentration (/enrichment) of ore.
ii) Taking out the metal from the concentrated ore: Highly reactive metals (K, Na, Ca, Mg, Al) are separated from their ore by the electrolysis of their molten chloride or oxides. Moderately reactive metals (Zn-Hg) are extracted by reducing their oxides with carbon or with a metal of higher reactivity. Some metals which occur in carbonate or oxide forms are first converted into their oxide forms and then reduced. Less reactive metals (Cu, Hg, Ag, Au, Pt) are found in their native states. Cu and Hg are found in sulphide forms and can be extracted by simply heating them in the presence of oxygen.
iii) Refining of metals: The metals which are taken out still contain some impurities. The process of purifying impure metals is called refining. Metals are mostly refined through electrolysis i.e electrolytic refining.
Q. What is aqua regia?
A. Aqua regia, (Latin for ‘royal water’) is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1. It can dissolve gold, even though neither of these acids can do so alone. Aqua regia is a highly corrosive, fuming liquid. It is one of the few reagents that is able to dissolve gold and platinum.
Q. Differentiate between:
a. Mineral and Ore
b. Calcination and Roasting
c. Corrosion and Rusting
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