Ch. No. 8. Understanding Metals and Non – metals
Fill in the blanks :
1. ....................... element that has the highest melting point.
2. ....................... is the only non-metal in liquid state.
3. Chocolates are wrapped in an aluminium foil, this is an application of
property of ....................... .
4. PVC stands for....................... .
5. Metal oxides are usually ....................... in nature.
6. Aluminium oxide is ....................... in nature.
7. Metals react with water to form a metal hydroxide and ....................... gas
is liberated.
8. Metals react with dilute acids to give ....................... and .......................
gas is liberated.
9. Sodium is a ....................... coloured metal.
10. Chlorine is a ....................... .
11. The most unreactive metals i.e. which are not affected by air and water
e.g. silver, gold and platinum are generally found in ....................... state.
12. The symbol of Aluminium is ....................... .
13. The valency of aluminium is ....................... .
14. Aluminum undergoes an oxidation reaction forming a thin layer of
....................... .
15. Potassium is the ....................... metal.
16. Pure gold is ....................... gold.
17. Pure gold is alloyed with ....................... or ....................... to make ornaments.
18. Aqua regia can dissolve metals like....................... and ....................... .
A. Answers
1. Tungsten
2. Bromine
3. Malleability
4. Poly vinyl chloride
5. Basic
6. Amphoteric
7. Hydrogen
8. Salt and hydrogen gas
9. Silver
10. Non – metal
11. Free or native
12. Al
13. 3
14. Aluminium oxide
15. Most reactive
16. 24 karat
17. Silver or copper
18. Gold and platinum
Name the following:
1. Metal which forms an amphoteric oxide?
Ans. Aluminium oxide.
2. An alloy of copper and zinc.
Ans. Brass
3. A compound which is added to lower the fusion temperature of an electrolytic bath in extraction of aluminium.
Ans. Cryolite.
4. A metal which does not react with cold water but reacts with steam.
Ans. Aluminium.
5. A common ore of aluminium.
Ans. Bauxite.
From the list of characteristic given below select the five which are relevant to metals and their compounds.
1. Ductile
2. Conduct electricity
3. Acidic oxide.
4. Discharged at anode basic oxides.
5. Brittle
6. (1, 2, 3) valence electrons.
7. Discharged at cathode.
8. (5, 6, 7) valence electrons.
9. Occurring in solid or gaseous state.
10. Basic oxides.
Ans. Characteristics of metal are :
1. Ductile
2. Conduct of electricity.
3. Basic oxides
4. (1, 2, 3) valence electrons.
5. Discharged at cathode.
DEFINE
Minerals
Gangue
Ores
Metallurgy
Roasting
Sonorous.
Malleability.
Ductility.
Anodising.
Ionic bond.
Covalent bond.
Covalent compound.
Reactivity series of metals.
Calcination.
Electroplating .
Corrosion.
Alloy.
Galvanising.
Tinning.
GIVE SCIENTIFIC REASONS
Sodium is stored under kerosene.
Gold and silver are used to make jewellery.
Calcium floats over water during the reaction with water.
Ionic compounds have high melting and boiling points
Tarnished copper utensils are cleaned with lime juice or tamarind.
Copper is exposed to air.
Reason for use of fused cryolite (Na3AlF6) along with fluorspar (CaF2) which is added to the electrolytic mixture containing pure alumina.
Electrolysis of active metals like Na, K, Al is not carried out by using aqueous solution of their chloride.
Elements like gold, silver are found in free or native state.
Pure water is a poor conductor of electricity but aqueous solution of NaCl conducts electricity.
An aqueous solution of sodium chloride conducts electricity.
Ionic compounds are formed due to the combination of metals and nonmetals.
Some elements occur in free state while others occur in the combined state.
Sodium and chlorine are poisonous substances but sodium chloride is edible.
Aluminium oxide is an amphoteric oxide.
Kitchen articles like pressure cooker, pan etc. are anodized.
ANSWER THE FOLLOWING IN DETAIL
Sudha dipped a copper coin in a solution of silver nitrate. After some time she saw the silver shine on the coin. Why? Give the balanced chemical equation for the same.
Metal A has electronic configuration of (2,8,1) and metal B has (2,8,8,2) which is more reactive. Identify these metals and vie their reactions with dil HCl.
To obtain (zinc) Zn from zinc sulphide two chemical reaction are involved
When steam is passed over aluminium.
Extraction of copper from its sulphide ore.
Thermit reaction.
When magnesium reacts with hot water.
What happens when aluminium oxide dissolves in aqueous sodium hydroxide?
In the extraction of aluminium
Write two methods of preventing rusting of iron.
What is an alloy? Give two examples with their chemical composition.
Arrange the following metals in the decreasing order of chemical reactivity, Cu, Mg, Fe, Na, Ca, Zn.
Explain the formation of an ionic compound between metal and a non – metal by transfer of electrons with Mg as the metal and Cl as a non – metal to illustrate your answer.
An element X on reacting with oxygen forms an oxide X2O. This oxide dissolves in water and turns red litmus blue. State whether element X is a metal or a non – metal. Explain with proper example.
Explain the properties of ionic compounds.
Write a short note on anodizing.
SCIENCE & TECH.
CH. NO. 1 SCHOOL OF ELEMENTS
CH. NO. 2 THE MAGIC OF CHEMICAL REACTIONS
CH. NO. 3 ACID BASE CHEMISTRY
CH. NO. 4 ELECTRIC SPARK
CH. NO. 5 ELECTROMAGNETISM
CH. NO. 6 WONDERS OF LIGHT PART - I
CH. NO. 7 WONDERS OF LIGHT PART II
CH. NO. 8 UNDERSTANDING METALS NON METALS
CH. NO. 9 AMAZING WORLD OF CARBON COMPOUNDS
CH. NO. 10 LIFE'S INTERNALSECRETS
CH. NO. 11 REGULATORS OF LIFE
CH. NO. 12 LIFE CYCLE
CH. NO. 13 MAPPING OUR GENES
CH. NO. 14 STRIVING FOR BETTER ENVIRONMENT PART I
CH. NO. 15 STRIVING FOR BETTER ENVIRONMENT PART - II
