The Periodic Table Chapter#4 Elements arranged in Periodic Table, Groups and Periods, Metalloids, Alkali metals , The Transition metal, Catalyst and Assessments IGCSE

The Periodic Table

Chapter#4

Objective Learning

After this Chapter Students will be able to understand:

ü  Elements arranged in Periodic Table

ü  Groups and Periods

ü  Metalloids

ü  Alkali metals

ü  The Transition metal

ü  Catalyst

 

                                                   THE PERIODIC TABLE

Elements arranged in Periodic Table:

In Periodic table elements are arranged on the basis of increasing atomic number.

Groups of the Periodic table:

Groups:

The vertical columns in the periodic table are called groups.

1. Periodic table consists of eight groups.
2. First group elements are called alkali metals.
3. Second group elements are called alkaline earth metals.

4.  Group-VII elements are called halogens.

5.  Group-VIII elements are called Noble gases or Inert    gases.

 

                                      Class Assessment

1. In Periodic table elements are arranged on the basis of increasing ……………. number.

1. Mass                             b. atomic                        c. neutron

2. The vertical columns in the periodic table are called?

1. Groups                          b. Periods                     c. atoms

3. Group-VII elements are called ………….?

a. Inert                                 b. noble                     c. Halogens

 

Periods of the Periodic table:

Periods:

The horizontal row in the Periodic table are called Periods.

1. Periodic table consist of seven Periods.
2. 1^st Period has two elements (H and He).
3. 2^nd and 3^rd Period each has 8 elements.
4. 4^th and 5^th Period each has eighteen elements.
5. 6^th Period has 32 elements.
6. 7^th Period has 32 elements and it is incomplete.

 

Information's we get from Group number and period number

 

➢    Group number tells the number of valence electrons(outer most shell electrons of an atom).

e.g. (i) Na has one valence electron because it is present in Group-I.

       (ii) Mg has two valence electrons because it is present in Group-II.

➢    Period number tells  the total number of shells of an atom.

e.g. (i) Li has two shells because it is present in 2^nd period.

(ii) K has four shells because it is present in 4^th period.

 

Metalloids:

These are the elements that behave as metals as well as non metals.

E.g. i) Silicon (Si)

ii) Germanium (Ge)

In Periodic table metalloids are present on the borderline between metals and non metals.

Alkali metals:

Group-I metals are called alkali metals because on reaction with water they produce alkaline. i.e.

Li, Na, k, Rb, Cs, Fr

 

Reactions of the Alkali metals:

The alkali metals get more reactive going down the group.

Compounds formed by group 1 metals are usually white solids (that dissolve in water to form colourless solution).

For Example,

Lithium    +     Water       →           lithium hydroxide    +  hydrogen

2 Li           +      2H₂O             →          2LiOH           +          H₂

 

                                    Class-Assessment

1. These are the elements that behave as metals as well as non metals?

1. Metalloids               b. metals               c.  Alkali

2. Group-I metals are called ……… metals ?

1. Metalloids               b. metals               c.  Alkali

3. Compounds formed by group-1 metals are usually ……….solids ?

a. Black                        b. White                c. yellow

 

Uses of Lithium compound:

1. Medicine          To treat mental illness.
2. Kill germs          In swimming pool
3. Glass                 In making tubes inside TV,s and for lenses
4. Dyes                  To dye nylon and paper
5. Ceramics          To the nose cones of rockets

 

The Transition metal:

The transition metals lie in between Group 2 and Group 3.

Some well-known transition metals are iron, copper, chromium, nickel and gold.

Physical properties:

1. The transition metals are typical metals.
2. They are hard, dense and shiny.
3. They are good conductors of heat and electricity.
4. They are malleable and ductile.
5. Iron, cobalt and nickel are the magnetic metals.

 

                                             Class-Assessment

1. The transition metals lie in between ……..and Group 3?

1. Group 7                      b. group 8                   c. group 2

2. …………. are malleable and ductile?

1. Atoms                          b. Ion                          c. Metals

3. Iron, cobalt and nickel are the………. metals.

a. Active                          b. rare                         c. magnetic

 

Transition metal compound:

The transition metals are less reactive than group 1 metals.

Transition metals form coloured compounds.

Catalyst:

We use catalysts in industry to speed up reactions.

The transition metals and their compounds are important catalysts.

For example:

Manufacture of ….                 Catalyst

Ammonia                                  iron

Margarine                                 nickel

 

                                             Class Assessment

1. Transition metals form ………… compounds?

1. White                         b. coloured                      c. solid

2. We use catalysts in industry to ………… reactions?

1. Slow up                       b. Speed up                     c. stop up

3. The catalyst used in the manufacturing of margarine?

1. Nickel                           b. Platinum                 c. Iron

4. The catalyst used in the manufacturing of Ammonia?

a. Nickel                           b. Platinum                 c. Iron