Chapter 3: Metals and Non Metals

Question 1

Physical Properties of Metals

Answer 1

● Hard and have a high tensile strength
● Solids at room temperature
● Sonorous
● Good conductors of heat and electricity
● Malleable, i.e., can be beaten into thin sheets
● Ductile, i.e., can be drawn into thin wires
● High melting and boiling points (except Caesium (Cs) and Gallium (Ga))
● Dense, (except alkali metals). Osmium - highest density and lithium - least density
● Lustrous
● Silver-grey in colour, (except gold and copper)

Question 2

Physical Properties of Non-Metals

Answer 2

● Occur as solids, liquids and gases at room temperature
● Brittle
● Non-malleable
● Non-ductile
● Non-sonorous
● Bad conductors of heat and electricity

Question 3

Exceptions in Physical Properties

Answer 3

● Alkali metals (Na, K, Li) can be cut using a knife.
● Mercury is a liquid metal.
● Lead and mercury are poor conductors of heat.
● Mercury expands significantly for the slightest change in temperature.
● Gallium and caesium have a very low melting point
● Iodine is non-metal but it has lustre.
● Graphite conducts electricity.
● Diamond conducts heat and has a very high melting point.

Question 4

Chemical Properties of Metals

Answer 4

● Alkali metals (Li, Na, K, etc) react vigorously with water and oxygen or air.
● Mg reacts with hot water.
● Al, Fe and Zn react with steam.
● Cu, Ag, Pt, Au do not react with water or dilute acids.

Question 5

Reaction of Metals with Oxygen (Burnt in Air)

Answer 5

Metal + Oxygen → Metal oxide (basic)
● Na and K are kept immersed in kerosene oil as they react vigorously with air and catch
fire.
4K(s) + O2(g) → 2K2O(s) (vigorous reaction)
● Mg, Al, Zn, Pb react slowly with air and form a protective layer that prevents corrosion.
2Mg(s) + O2(g) → 2MgO(s) (Mg burns with a white dazzling light)
4Al(s) + 3O2(g) → 2Al2O3(s)
● Silver, platinum and gold don’t burn or react with air.

Question 6

Basic Oxides of Metals

Answer 6

Some metallic oxides get dissolved in water and form alkalis. Their aqueous solution turns red litmus blue.
Na2O(s) + H2O(l) → 2NaOH(aq)
K2O(s) + H2O(l) → 2KOH(aq)

Question 7

Amphoteric Oxides of Metals

Answer 7

Amphoteric oxides are metal oxides which react with both acids as well as bases to form salt and water.
For example - Al2O3,ZnO, P bO, SnO
Al2O3(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2O(l)
Al2O3(s) + 2NaOH(aq) → 2NaAlO2(aq) + H2O(l)
ZnO(s) + 2HCl(aq) → ZnCl2(aq) + H2O(l)
ZnO(s) + 2NaOH(aq) → Na2ZnO2(aq) + H2O(l)

Question 8

Reactivity Series

Answer 8

K Potassium ( Highly Active Metal)
Ba Barium
Ca Calcium
Na Sodium
Mg Magnesium
Al Aluminium
Zn Zinc
Fe Iron
Ni Nickel
Sn Tin
Pb Lead
H Hydrogen
Cu Copper
Hg Mercury
Ag Silver
Au Gold
Pt Platinum

Question 9

Reaction of Metals with Water or Steam

Answer 9

Metal + Water → Metal hydroxide or Metal oxide + Hydrogen

2Na + 2H2O(cold) → 2NaOH + H2 + heat
Ca + 2H2O(cold) → Ca(OH)2 + H2
Mg + 2H2O(hot) → Mg(OH)2 + H2
2Al + 3H2O(steam) → Al2O3 + 3H2
Zn + H2O(steam) → ZnO + H2
3Fe + 4H2O(steam) → Fe3O4 + 4H2

Question 10

Reaction of Metals with Acid

Answer 10

Metal + dilute acid → Salt + Hydrogen gas

2Na(s) + 2HCl(dilute) → 2NaCl(aq) + H2(g)
2K(s) + H2SO4(dilute) → K2SO4(aq) + H2(g)
Only Mg and Mn, react with very dilute nitric acid to liberate hydrogen gas.
Mg(s) + 2HNO3(dilute) → Mg(NO3)2(aq) + H2(g)
Mn(s) + 2HNO3(dilute) → Mn(NO3)2(aq) + H2(g)

Question 11

Displacement Reaction

Answer 11

A more reactive element displaces a less reactive element from its compound or solution.

Question 12

How Do Metal React with Solution of Other Metal Salts

Answer 12

Metal A + Salt of metal B → Salt of metal A + Metal B

Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)
Cu(s) + 2AgNO3(aq) → Cu(NO3)(aq) + 2Ag(s)

Question 13

Reaction of Metals with Bases

Answer 13

Base + metal → salt + hydrogen

2NaOH(aq) + Zn(s) → Na2ZnO2(aq) + H2(g)
2NaOH(aq) + 2Al(s) + 2H2O(l) → 2NaAlO2(aq) + 2H2(g)