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Kerala Syllabus Std 9 Chemistry Chapter 2 Periodic Table Extra Questions and Answers
Question 1.
What are groups and periods in the modern periodic table.
Answer:
In the periodic table, the horizontal rows are called periods, and the vertical columns are called
groups.
Question 2.
How did Henry Moseley prove that the properties of elements depend mainly on atomic number rather than atomic mass?
Answer:
Through the X-ray diffraction studies.
Question 3.
Which one of the following statements is true?
a) The biggest atom in a period will be that of the alkali metal.
b) From left to right in a period, the size of atoms of elements increases.
Answer:
a) The biggest atom in a period will be that of the alkali metal.
Question 4.
Find out the relation and fill in the blanks
Group 1 : Alkali metals
Group 2: …………….
Answer:
Alkaline earth metals.
Question 5.
What is the total number of groups in the periodic table?
Answer:
18
Question 6.
Match the following suitably
| A | B | C |
| Noble gases | Elements of group 3 to 12 | Known as rare earths |
| Lanthanoids | Elements of group 18 | Gives coloured compounds |
| Transition elements | Kept as separate row below the periodic table | Do not take part in chemical reactions |
Answer:
| A | B | C |
| Noble gases | Elements of group 18 | Do not take part in chemical reactions |
| Lanthanoids | Kept as separate row below the periodic table | Known as rare earths |
| Transition elements | Elements of group 3 to 12 | Give coloured compounds |
Question 7.
Which one of the following does not belong to the same group?
a) Fluorine
b) Chlorine
c) Bromine
d) Neon
Answer:
d) Neon
Neon is a noble gas. Others are halogens.
Question 8.
Match the following
| A | B |
| Silicon | Noble element |
| Helium | 7th period |
| Lanthanides | Metalloid |
| Actinides | Rare earths |
Answer:
| A | B |
| Silicon | Metalloid |
| Helium | Noble element |
| Lanthanides | Rare earths |
| Actinides | 7th period |
Question 9.
How does the increase in the number of shells influence the size of an atom?
Answer:
When the number of shells increases, the size of the atom also increases
Question 10.
What do you mean by the modern periodic Law?
Answer:
The chemical and physical properties of elements are periodic functions of their atomic numbers.
Question 11.
The scientist, known as “the father of Periodic table”, is ………………….
Answer:
Dmitri Mendeleev
Question 12.
Symbols of some atoms are given, (symbols are not real)
\({ }_8^{17} \mathrm{P}\) \({ }_18^{40} \mathrm{Q}\) \({ }_8^{16} \mathrm{P}\) \({ }_20^{40} \mathrm{R}\)
a) Which among these is an isotopic pair? Give reason.
b) How many neutrons are present in Q?
Answer:
a) \({ }_8^{17} \mathrm{P}\) & \({ }_8^{16} \mathrm{P}\)
Atoms of the same element have the same atomic number but different mass numbers.
b) 22
Question 13.
The names of some scientists related to the classification of elements are given in the box.
Lavoisier, Dobereiner, Newlands, Mendeleev, Moseley
Identify the names related to the statements given below.
a) The known 30 elements were classified into metals and non-metals.
b) Columns were left vacant for elements that were not known at that time, and their properties were predicted.
c) Serial numbers were given to the elements through X-ray diffraction experiments,
Answer:
a) Lavoisier
b) Mendeleev
c) Moseley
Question 14.
An element in the 11th group contains electrons in four shells.
a) To which period does this element belong?
b) Name the family of this element.
(alkali metals, alkaline earth metals, halogens, transition elements.)
c) Write any two properties of the elements of this family.
Answer:
a) 4
b) Transition elements
c)
- They are metals.
- They form coloured compounds
Question 15.
The maximum number of electrons that can be accommodated in the outermost shelFof an element is …………………….
(12, 10, 8, 18)
Answer:
8
2.
Analyse the electronic configurations of the elements given below and answer the following questions, (symbols are not real)
P – 2, 7
Q – 2, 8, 2
R – 2, 8, 8
a) R is the most stable element. Why?
b) Which one of these elements donates its electrons in chemical reactions?
Answer:
a) Octet electron configuration. (The arrangement of 8 electrons in the outermost shell),
b) Q
Question 16.
The mass number of an element is 27. The M shell of its atom contains 3 electrons.
a) Write the electronic configuration of this atom.
b) What is the atomic number of this element?
c) How many neutrons are present in this atom?
Answer:
a) 2, 8, 3
b) 13
c) Number of neutrons = Mass number – Atomic number = 27 – 13 = 14
Question 17.
The electronic configuration of certain elements is given in the table.
| Element | Electronic configuration |
| X | 2, 8, 7 |
| Y | 2, 8, 8 |
| Z | 2, 8, 1 |
a) Which element has the biggest atom?
b) Name the family to which the element ‘Y’ belongs.
c) Which among these has the highest electronegativity?
Answer:
a) Z
b) Noble gases (Inert gases)
c) X
Question 18.
There are 5 electrons in the M shell of an atom.
a. To which group does this element belong?
b. To which period is this element included?
c. How many elements are present in the period in which this element belongs?
d. Write the electronic configuration of the element just above it in the same group.
Answer:
a. 15
b. 3
c. 8
d. 2, 5
Question 19.
The third shell (M shell) of an element X contains 7 electrons. Its mass number is 35
a) Write the electronic configuration of the element.
b) What is the atomic number of the element?
c) Write the number of neutrons in this element.
d) Write the symbol of the ion of this element.
Answer:
a) 2, 8, 7
b) 17
c) No: of neutrons = Mass number – atomic number = 35 – 17 = 18
d) X–
Question 20.
A part of the periodic table is given (symbols are not real)
| X | 6Y | Z |
| 13P | Q | R |
a) Identify the group to which P belongs.
b) Write the electronic configuration of the inert gas in the period in which Pn included.
c) Which one of these elements has the highest metallic character?
d) Write the electronic configuration of element Q?
Answer:
a) 13
b) 2, 8, 8
c) 13P
d) 2, 8, 4
Question 21.
Symbols of certain elements are given. Write their electronic configuration and find the period and group in which they are included.
a) \({ }_{6}^{12} \mathrm{C}\)
b) \({ }_{12}^{24} \mathrm{Mg}\)
c) \({ }_{17}^{35} \mathrm{Cl}\)
d) \({ }_{13}^{27} \mathrm{Al}\)
e) \({ }_{10}^{20} \mathrm{Ne}\)
Answer:
a) Electronic configuration – 2, 4 Period – 2 Group – 14
b) Electronic configuration – 2, 8, 2 Period – 3 Group – 2
c) Electronic configuration – 2, 8, 7 Period – 3 Group – 17
d) Electronic configuration – 2, 8, 3 Period – 3 Group – 13
e) Electronic configuration – 2, 8 Period – 2 Group – 18
Question 22.
The elements belonging to group 18 in the periodic table are called ………………..
Answer:
Noble gas elements
Question 23.
Find the relationship and fill it suitably
Sodium: Metal
Germanium: ………………….
Answer:
Metalloid
Question 24.
Some elements and their electronic configuration are given in the table.
(Hint: Symbols are not real)
| Element | Electronic configuration |
| A | A |
| B | B |
| C | C |
a) Among these elements, which has the highest stability? Give reason.
Answer:
a) B
Reason: Element B has 8 electrons in the outermost shell.
Question 25.
Lanthanoids and Actinoids belong to the 6th and 7th periods, respectively of the periodic table
a. These elements are together known as ………………
(Representative elements, Transition elements. Inner transition elements)
b. Which of them is known as rare earths?
Answer:
a. Inner transition elements.
b. Lanthanoids
Question 26.
a) Write the electronic configuration of \({ }_{10}^{20} \mathrm{Ne}\) and find its group number
b) Does this element generally take part in chemical reactions? Why?
Answer:
a) Electron configuration of \({ }_{10}^{20} \mathrm{Ne}\) – 2, 8
Group number – 18
b) No. The outermost shell is completely filled (octet – 8 electrons), thus they are stable and do not take part in chemical reaction.
Question 27.
Atomic number of an element Y is 16 (Symbol is not real).
a. Write the electronic configuration of this element.
b. To which period does this element belong?
c. To which family of elements does this element belong?
Answer:
a) 2, 8, 6.
b) Third period
c) Oxygen family
Question 28.
The symbol of Argon atom is \({ }_{18}^{40} \mathrm{Ar}\)
a. How many electrons are there in an Argon atom?
b. Draw the Bohr model of this atom?
c. Which shell of Argon atom has the highest energy?
Answer:
a) 18
b) 
c) M (3rd shell)
Question 29.
Choose the correct statements among the following.
i. As the size of an atom increases, ionisation energy increases.
ii. As the size of the atom decreases, electronegativity increases.
iii. As the size of the atom increases, its metallic character increases.
iv. The size of the atom increases on moving from left to right in a period.
Answer:
ii. As the size of an atom decreases, electronegativity increases.
iv. The size of the atom increases on moving from left to right in a period.
Question 30.
What happens to the size of an atom when we go from left to right in a period? Explain the reason.
Answer:
From left to right in a period with an increase in atomic number, electrons are added to the same shell and the nuclear charge increases. Thus, size decreases.