In this post, you will find answers/solutions to the exercise questions of Chapter 3 "Periodic table and Periodicity of Properties" for Grade IX level students. These answers are simple, comprehensive, and to the point.
Students should solve these answers after covering the topics, that they learned in the Short questions-answers as well as the Long questions-answers section of the same chapter. If they don't find answers to some exercise questions given in their textbook, then it means they are already attempted in the Short and Long answers section of the same chapter.
Choose the correct options.
1. Which of the following elements is in the same family as fluorine
(a) silicon
(b) antimony
(c) iodine
(d) arsenic
2. Which of the following would have the smallest ionization energy
(a) K
(b) P
(c) S
(d) Ca
3. An element has configurations 2, 8, and 1. It belongs to
(a) group I and III period
(b) group III and I period
(c) group I and VII period
(d) group VII and III period
4. Which of the following elements would be most similar to Carbon
(a) nitrogen (b) boron (c) oxygen (d) silicon
5. S-block elements are
(a) Non metals
(b) Metals
(c) Metalloids
(d) Transition
6. Which of the following would have the largest ionization energy
(a) Na
(b) Al
(c) H
(d) He
7. Elements in a ____________ have similar chemical properties.
(a) period
(b) group
(c) both a and B
(d) neither a nor b
8. An element has eight (8) electrons in its valence shell. It is a member of
(a) alkali family
(b) halogen family
(c) Noble family
(d) Carbon family
9. The modern periodic table is based on
(a) atomic numbers
(b) mass number
(c) neutron number
(d) isotope number
10. The shielding effect is due to
(a) neutron
(b) proton
(c) proton and neutron
(d) electron
Which element of group IA is not an alkali metal and why?
Group-IA of the periodic table is called alkali metals. They are named so because they form base (Alkali is an Arabic name of base) when reacting with water. However, there is only Hydrogen in this group which does not form a base when reacting with water. So, the Hydrogen of Group-IA is not an alkali metal because it does not form a base i.e. alkali.
Name the group and state the group number of each of the following elements.
(a) K (b) Ne (c) Be (d) Cl (e) C
|
Element |
Group Number |
Group Names |
|
K |
Group-IA |
Alkali metal |
|
Ne |
Group-VIIIA |
Noble gases |
|
Be |
Group-IIA |
Alkaline earth metals |
|
Cl |
Group-VIIA |
Halogens |
|
C |
Group-IVA |
Carbon family |
Which element is the most electronegative among C, N, O, Br and S? Which group does it belong to?
Among all these elements Oxygen (O) is most electronegative and belongs to Group-VI i.e. Oxygen family.
Vi: Which element is found in
i. Period 2, Group-VII ii. Period 4, Group-III
iii. Period 5, Group-VI iv. Period 1, Group-VIII
a) Fluorine (F) is present in Period-2 group-VIIA
b) Gallium (Ga) is present in Period-4 group-IIIA
c) Tellurium (Te) is present in Period-5 group-VIA
d) Helium (He) is present in Period-1 group-VIIIA
How will you differentiate between representative and transition elements?
|
Representative elements |
Transition elements |
|
Elements present in sub-group
A of the periodic table are called representative elements. |
Elements present in sub-group
B of the periodic table are called transition elements. |
|
They have fix oxidation
state. |
They have variable oxidation
states. |
|
Some of them are metals, some
are non-metals and some are metalloids in nature. |
They are all metallic in
nature. |
|
They are present in the s and p
blocks of the periodic table. |
They are present in the d and f
blocks of the periodic table. |
Why do the s-block elements have two groups only?
Elements of two groups (IA
& IIA) have their s-orbital involved in bond formation
In the periodic table, elements are placed in blocks on the basis of the involvement of orbital in bond formation. For example, the elements having s-orbital involved in bond formation are placed in s-block, similarly, the elements having p-orbital involved in bond formation are placed in p-block and so on.
In the periodic table, there are the first two groups i.e. Alkali metals and Alkaline earth metals, which have their s-orbital involved in the bond formation. So there are only two groups in s-block. Other groups have either p, d or f-orbital involve in bond formation.
What type of element is Sulphur (S), a representative element, a transition element or a lanthanide element?
In order to decide this, we will first write down the electronic configuration of Sulphur (S) having the atomic number 16 i.e. 〖1s2, 2s2, 2s6, 3s2, 3p4. It is clear from the electronic configuration that the p sub-shell is involved in the bond formation of Sulphur and all the p block elements are representative elements. So, Sulphur is a representative element.
How the modern periodic table is different from Mendeleev’s periodic table.
Difference between Modern and
Mendeleev’s periodic law
|
Basis of distinction |
Modern periodic law |
Mendeleev’s periodic law |
|
Definition |
The physical and chemical
properties of the elements are the periodic functions of their atomic
numbers. |
The physical and chemical properties
of the elements are the periodic functions of their atomic masses. |
|
Basis of the law |
This law is based on the atomic
numbers of elements. |
This law is based on the atomic
masses of elements. |
|
Form of the periodic table |
Because of having a large number
of elements the periodic table formed on the basis of modern periodic law is
called the Long form of the periodic table. |
Because of having fewer elements the periodic table formed on the basis of Mendeleev’s periodic law
is called the Short form of the periodic table. |
|
Accuracy |
This law is accurate. |
This law is not accurate. |
|
Position of Isotopes |
All isotopes have the same
atomic numbers, so they occupy only one position in the modern periodic table. |
In Mendeleev’s periodic table
the position of isotopes was not fixed. |
Why is Fluorine special in terms of electronegativity?
Fluorine is special in terms of electronegativity
As we know Fluorine (F) has the maximum electronegativity value in the whole periodic table, so it is special in terms of electronegativity.
It is because of the smallest atomic size and higher nuclear charge of Fluorine that it has the maximum electronegativity value.
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