NCERT Solutions for Class 10 Science Chapter 5 - Periodic Classification Of Elements

Intext Exercise -1

1. Did Dobereiner’s Triads Also Exist in the Columns of Newlands’ Octaves? Compare and Find Out.

Ans: In the dobereiner's triads, the middle element atomic mass is equal to the average atomic mass of the first and third element. Only one Dobereiner’s triad exists in the columns of Newlands’ Octaves.

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Newlands’ Octaves

2. What Were the Limitations of Dobereiner’s Classification?

Ans: Limitation of Dobereiner’s Classification: 

Only a few elements can be arranged in the Dobereiner's triads. It depends on their properties. F, Cl, Br will not show the triads but Cl , Br, I will show.

3. What Were the Limitations of Newlands’ Law of Octaves?

Ans: Limitations of Newlands’ law of octaves: 

(i)  It was applicable up to lighter elements (Calcium only). 

(ii)  The properties after calcium do not have any resemblance to the properties of the above element. 

(iii) Co and Ni are transition elements but they were placed in the group of F, Cl. 

(iv) Iron properties are similar to the cobalt and nickel but placed in different columns.

Intext Exercise -2

1. Use Mendeleev’s Periodic Table To Predict the Formula for the Oxides of the Following Elements: K, C, Al, Si, Ba.

Ans: Potassium is in group 1. The oxide will be ${{K}_{2}}O$ . 

Carbon is in group 4. The oxide will be $C{{O}_{2}}$ . 

Aluminium is in group 3. The oxide will be $A{{l}_{2}}{{O}_{3}}$ . 

Silicon is in group 4. The oxide will be $Si{{O}_{2}}$ . 

Barium is in group 2. The oxide will be $BaO$ .

2. Besides Gallium, Which Other Elements Have Since Been Discovered That Were Left by Mendeleev in His Periodic Table? (Any Two)

Ans: Gallium(Ga) and Scandium(Sc)

3. What Were the Criteria Used by Mendeleev in Creating His Periodic Table?

Ans: Mendeleev’s periodic table was based on the atomic masses of the elements. The properties of the elements are the periodic function of their atomic masses. Elements are arranged in the increasing atomic mass and their properties reoccur after regular intervals.

4.

a) Lithium, Sodium, Potassium Are All Metals That React With Water To Liberate Hydrogen Gas. Is There Any Similarity in the Atoms of These Elements?

Ans: Yes, all the three elements lithium, sodium, and potassium have one electron in the valence shells.

b) Helium is an Unreactive Gas and Neon is a Gas of Extremely Low Reactivity. What, if Anything, Do Their Atoms Have in Common?  

Ans: Helium (He) and neon (Ne) are inert gas. Their outermost shells are completely filled. Helium has a duplet in its K shell, while neon has an octet in its K, L shell.

5. In the Modern Periodic Table, Which are the Metals Among the First Ten Elements?

Ans: Lithium (Li) and beryllium (Be) are metals among the first ten elements.

6. By Considering Their Position in the Periodic Table, Which One of the Following Elements Would You Expect To Have Maximum Metallic Characteristic? Ga, GE, As, Se and Be.

Ans: Be and Ga are expected to be more metallic but Metallic character increases when we go from top to bottom. Due to its larger size for gallium, it is the most metallic among the given elements.

NCERT Exercises

1. Which of the following statements is not a correct statement about the trends when going from left to right across the periods of the periodic Table?

1. The elements become less metallic in nature.

2. The number of valence electrons increases.

3. The atoms lose their electrons more easily.

4. The oxides become more acidic.

Ans: (c) The atoms lose their electrons more easily. 

(In this period, the atom's size decreases so it is difficult to lose their electrons.)

2. Element X forms a Chloride with the Formula $XC{{l}_{2}}$ , Which is a Solid with a High Melting Point. X would most likely be in the same group of the Periodic Table as

a) Na 

Ans: Valency of X in the given compound is 2. But Na is in group 1 in the periodic table. Hence, it does not form the given compound with chloride.

b) Mg 

Ans: Valency of X in the given compound is 2. Mg is in the group 2 in the periodic table. 

c) Al 

Ans: Valency of X in the given compound is 2. But Al is in the group 3A in the periodic table. Hence, it does not form the given compound with chloride.

d) Si

Ans: Valency of X in the given compound is 2. But the valence of Si is 4. Hence, it does not form the given compound with chloride.

3. Which Element has

a) Two shells, both of which are completely filled with electrons? 

Ans: Neon has two shells, both of which are completely filled with Electrons

b) The Electronic Configuration 2, 8, 2? 

Ans: Magnesium electronic configuration is 2, 8, 2.

c) A Total of Three Shells, With Four Electrons in its Valence Shell?

Ans: Silicon has three shells, with four electrons in its valence shell  

d) A total of two shells, with three electrons in its valence shell?

Ans: Boron has two shells, with three electrons in its valence shell  

e) Twice as many electrons in its second shell as in its first shell?

Ans: Carbon has twice as many electrons in its second shell as in its first shell.

4.

a) What property do all elements in the same column of the Periodic Table as boron have in common?

Ans: All the elements have the same number of valence electrons and the valency is equal to 3.

b) What property do all elements in the same column of the Periodic Table as fluorine have in common?

Ans: All the elements have the same number of valence electrons and they all have valency equal to 1.

5. An Atom Has Electronic Configuration 2, 8, 7.

a) What is the atomic number of this element?

Ans: Atomic number of the given configuration is 17.

b) To which of the following elements would it be chemically similar? (Atomic numbers are given in parentheses.) 

N(7) F(9) P(15) Ar(18)

Ans: Fluorine electronic configuration is 2, 7. same number of valence    electrons in the outermost shell.

6. The Position of Three Elements A, B and C in the Periodic Table are Shown Below

a) State whether A is a metal or nonmetal.

Ans: A is a non-metal.

b) State whether C is more reactive or less reactive than A.

Ans: C is less reactive than A. Reactivity decreases down the group in halogens.

c) Will C be larger or smaller in size than B?

Ans: When we move from left to right, the atomic size decreases so C is smaller than B.

d) Which type of ion, cation or anion, will be formed by element A?

Ans: A is in group 17 so the valence electrons will be 7. It would form an anion and accept an electron to complete the octet.

7. Nitrogen (atomic number 7) and Phosphorus (atomic number 15) Belong to Group 15 of the Periodic Table. Write the Electronic Configuration of These Two Elements. Which of These Will Be More Electronegative? Why?

Ans: The electronic configuration of the group 15 elements.

Electronegativity is the tendency of an atom of an element in a molecule to attract the shared pair of electrons present between bonded atoms towards itself. When we move from left to right electronegativity increases and when we move from top to bottom the electronegativity decreases. In case of group 15, the electronegativity decreases. Nitrogen is more electronegative than phosphorus.

8. How Does the Electronic Configuration of an Atom Relate to its Position in the Modern Periodic Table?

Ans: In the modern periodic table, the period number of an element is equal to the number of shells in its atom. The group number of an element having up to two valence electrons is equal to the number of valence electrons. If more than two valence electrons is equal to the number of valence electrons plus 10.

9. In the Modern Periodic Table, Calcium (Atomic Number 20) is Surrounded by Elements With Atomic Numbers 12, 19, 21, and 38. Which of These Have Physical and Chemical Properties Resembling Calcium?

Ans: 

Elements with atomic number 12 and 38 have the same chemical properties as that of calcium. Because both of them have the same number of valence electrons.

10. Compare and Contrast the Arrangement of Elements in Mendeleev’s Periodic Table and the Modern Periodic Table.

Ans: 

NCERT Solutions for Class 10 Science Chapter 5 - Periodic Classification of Elements

Students who are looking for NCERT Solutions for Class 10 Science Chapter 5 - Periodic Classification of Elements PDF can opt for Upcoming Exams and also You can Find the Solutions of All the Science Chapters below.

NCERT Science Solutions Class 10 - Chapter wise PDF Download

• Chapter 1 - Chemical Reactions and Equations

• Chapter 2 - Acids, Bases and Salts

• Chapter 3 - Metals and Non-metals

• Chapter 4 - Carbon and Its Compounds

• Chapter 5 - Periodic Classification of Elements

• Chapter 6 - Life Processes

• Chapter 7 - Control and Coordination

• Chapter 8 - How do Organisms Reproduce?

• Chapter 9 - Heredity and Evolution

• Chapter 10 - Light Reflection and Refraction

• Chapter 11 - Human Eye and Colourful World

• Chapter 12 - Electricity

• Chapter 13 - Magnetic Effects of Electric Current

• Chapter 14 - Sources of Energy

• Chapter 15 - Our Environment

• Chapter 16 - Management of Natural Resources

NCERT Study Resources for Class 10 Science 

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• CBSE Revision Notes for Class 10 Science

• Important Questions for CBSE Class 10 Science, Chapter wise Questions with Answers

• NCERT Class 10 Science Book PDF

• NCERT Exemplar for Class 10 Science (Book Solutions)

• Download Syllabus for CBSE Class 10 Science Term (1 & 2)

• CBSE Class 10 Previous Year Question Paper

• CBSE Class 10 Sample Paper

NCERT Solutions for Class 10 Science Chapter 5 – Free PDF Download

By referring to the 5 Science class 10 solutions available for NCERT, the students are able to avail a simpler procedure of learning. It consists of various to the point question and answers, followed by proper explanations of different subtopics. This solution is what students can avail when they are trying to comprehend the basic concept behind this chapter.

This primary knowledge will prove to be useful when a student moves on towards later years of their education. To understand chemistry as a subject, having a clear concept about elements on the periodic table is necessary. 

Important Subtopics Covered in Class 10 Chapter 5

• Early Attempts At the Classification of Elements

• Mendeleev’s Periodic Table

• The Modern Periodic Table

Points Discussed in Chapter 5 

• Elements are classed according to how comparable their characteristics are. Newlands devised the Law of Octaves after Döbereiner divided the elements into triads.

• The elements were organized by Mendeléev in ascending order of their atomic weights and chemical characteristics.

• On the basis of gaps in his Periodic Table, Mendeléev even anticipated the presence of several yet-to-be-discovered elements.

• When the elements were organized in order of increasing atomic number, a fundamental attribute of the element identified by Moseley, anomalies in the arrangement of elements based on rising atomic mass could be addressed.

• The Modern Periodic Table divides elements into 18 vertical columns called groups and seven horizontal rows named periods.

• The periodicity of features such as atomic size, valency or combining capacity, and metallic and non-metallic character may be seen in this arrangement.

Benefits of NCERT Class 10 Solutions

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2. Students might have a better understanding of subjects by using elaborate answers.

3. Step-by-step explanations are provided for the numbers in this chapter.

4. The use of straightforward and logical language boosts students' confidence.

5. Wherever possible, pupils are given visual representations to help them absorb subjects more quickly.

Class 10 Science Chapter 5 - Periodic Classification of Elements Weightage 2024-25

The term 2 CBSE Class 10 Science exam is of 40 marks, with 10 marks on internal assessment, just like the weightage of the term 1 Science exam. Class 10 Science Chapter 5 Periodic Classification of Elements contributes to 10% of the exam. Here is the topic-wise weightage of the chapter.

NCERT Solutions for Class 10 Science Chapter 5 Exercises

• Exercise 5.1 – Early Attempts at the Classification of Tables

In this segment of chapter 5 science Class 10, students will learn how elements were classified in the periodic table based on their properties. These elements were segregated from one another on the basis of whether they were gases, metals or non-metals.

• Exercise 5.1.1 – Dobereiner's Triads

A German chemist, known to all as Johann Wolfgang Dobereiner, had attempted to group elements based on their properties. Formation of these groups was known as triads. 

• Exercise 5.1.2 – Newland's Laws of Octaves

In this section of the periodic classification of elements in Class 10 solutions, learn about how in this table, every eighth element displays properties that are similar to the first one. This law may appear in the examination so students will need to memorise it thoroughly. 

• Exercise 5.2 – Mendeleev's Periodic Table

In this section of the periodic classification of elements of class 10 NCERT solutions, an introduction to Mendeleev's periodic table has been provided. In this table, elements were arranged, based on their increasing atomic masses. 

• Exercise 5.2.1 – Achievements of Mendeleev's Periodic Table 

This periodic table present in Class 10 Science Chapter 5 NCERT solutions was able to predict the existence of certain elements that back then had not been discovered back then. These elements include Germanium (Ge), Gallium (Ga) and Scandium (Sc). 

• Exercise 5.2.2 – Limitations of Mendeleev's Periodic Table

In this periodic table present in Ch 5 Science Class 10 NCERT solutions, there is no explanation found about Isotopes. Hydrogen in this table does not have a fixed position, and Mendeleev also fails to provide any explanation regarding the atomic masses being in the wrong order for some elements. 

• Exercise 5.3 – Modern Periodic Table

Elements present in this table of Class 10 Periodic Classification of Elements solutions have been arranged on the basis of their increasing atomic masses. Students will need to learn the order of the elements in this periodic table for their examinations.  

• Exercise 5.3.1 – Position of Elements in the Modern Periodic Table

This modern periodic table that we find in Class 10 Science Ch 5 solutions, consists of 7 periods and 18 groups. Elements in a period are set on the basis of the maximum number of electrons present. 

• Exercise 5.3.2 – Trends in the Modern Periodic Table

There are different trends in the modern periodic table that have been noticed, which students will learn about in this section. Electronegativity, electron affinity, metallic character, atomic radius, etc. are some of the many trends. 

Benefits of NCERT Solutions for Class 10 Science Chapter 5

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• The solution is framed in a question and answer format to ease the process of learning. 

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• Help in building the foundation for a student's knowledge about the subject. 

• Solution is constructed in a step by step manner to help a student understand easily. 

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