NCERT Solutions for Class 10 Science Chapter 5 Periodic Classification of Elements
The NCERT Solutions for Class 10 Science Chapter 5 Periodic Classification of Elements are included in the study material to aid students in comprehending the classification of different elements on the periodic table based on their characteristics, i.e., whether they are metals or non-metals. The chapter is divided into sections, such as Dobereiner's table and Mendeleev's table, and their advantages and limitations. The activities included in the chapter are designed to make the learning process interesting for the students. The chapter also features three types of periodic tables to simplify the explanation of the topic. The students can refer to these solutions on our website to revise the complete syllabus and score higher marks in their examinations.
Topics Covered under NCERT Solutions for Class 10 Science Chapter 5 Periodic Classification of Elements
Chapter 5 covers various topics based on the periodic table and elements. Here are the topics covered.
- Dobereiner's Triads: This topic refers to Johann Dobereiner's Triads, a group of three elements with similar chemical properties. These elements have been arranged in increasing atomic masses.
- Newlands' Law Of Octaves- It discusses John Newlands' Law of Octaves, a classification of elements based on their properties. According to this law, every eighth element in the periodic table has similar properties.
- Mendeleev's Periodic Table: Its merits and demerits- This discusses Dmitri Mendeleev's Periodic Table, which is based on the atomic mass of the elements. The merits and demerits of this periodic table are also discussed.
- The Modern Periodic Table- discusses the modern periodic table, which is based on the atomic number of elements.
- Position of Elements in the Modern Periodic Table- It discusses the position of elements in the modern periodic table. It also discusses the arrangement of the elements in groups and periods.
- Trends in the Modern Periodic Table- It discusses the trends in the modern periodic table, such as atomic size, ionization energy, electronegativity, and metallic character.
NCERT Solutions for Class 10 Science Chapter 5 Intext Questions
1. Did Dobereiner’s triads also exist in the columns of Newlands’ Octaves ? Compare and find out.
Ans. Yes, Dobereiner’s triads also existed in the columns of Newland’s Octaves. For example, Li, Na, K.
2. What were the limitations of Dobereiner’s classification?
3. What were the limitations of Newlands’ law of octaves ?
1. Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements : K, C, Al, Si, Ba.
2. Besides gallium, which other elements have since been discovered that were left by Mendeleev in his periodic table? (any two)
Ans. Scandium and Germanium.
3. What were the criteria used by Mendeleev in creating his Periodic Table?
4. Why do you think the noble gases are placed in a separate group?
1. How could the Modern Periodic table remove various anomalies of Mendeleev’s periodic Table?
2. Name two elements you would expect to show chemical reactions similar to magnesium. What is the basis for your choice?
Ans. Mg (12) = 2, 8, 2 – two electrons in outermost shell
Oxide of Mg = MgO
Beryllium (Be) and Calcium (Ca).
Both Be (atomic number 4) and Ca (atomic number 20) have similar electronic configuration, i.e., two electrons in outermost shells.
Be 2, 2
Ca 2, 8, 8, 2
Both Be and Ca react with oxygen to give basic oxides, BeO and CaO.
Ans. (a) Lithium : Atomic number – 3, 1s2, 2s1 (2, 1); Sodium : Atomic number – 11, 1s2, 2s22p6, 3s1 (2, 8, 1);
(b) Beryllium : Atomic number – 4 (2, 2); 1s2, 2s2 Calcium : Atomic number – 20, 1s2, 2s22p6, 3s23p6, 4s2 (2, 8, 8, 2)
(c) Helium : Atomic number – 2, 1s2(2); Neon : Atomic number – 10, 1s2, 2s2 2p6 (2, 8);
Argon : Atomic number – 18, 1s2, 2s2, 2p6, 3s23p6 (2, 8, 8).
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 ?
(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. (a) The elements Li, Na and K are having similar properties as:
(i) They belong to the same group i.e., Group 1 in periodic table.
(ii) All having one valance electron in outermost shell.
Hence these metals (Li, Na, K) react with water to librate hydrogen gas.
(b) The outmost shell of both the atoms of He and Ne is completely filled.
Hence both He and Ne are very less reactive elements.
5. In the modern periodic table, which are the metals among the first ten elements?
Ans. The first ten elements in modern periodic table are hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine and neon. Out of these, lithium and beryllium are metals, whereas others are non-metals.
6. By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristics ?
Ga, Ge, As, Se, Be
Ans. As we move from left to right in a period, the metallic character decreases as the size of an atom also decreases and thus, the valence electrons are held tightly by nucleus. So it becomes hard to loose electrons resulting in decrease in metallic character.
The given elements Ga, Ge, As, Se belong to the same period 4 and Be occupies the most left position so it is most metallic among them.
NCERT Solutions for Class 10 Science Chapter 5 Exercise Questions
1. Which of the following statements is not a correct statement about the trends when going from left to right across the periods of Periodic Table.
Ans. (c) The atoms lose their electrons more easily.
Explanation: When we move from left to right across the periods, the size of an atom decreases and the number of valence electrons increases, the nucleus is tightly bound to increase the metallic character. So they can not loose their electrons easily.
Ans. (b) Mg
Explanation: This is becuase both Na and Mg belong to same period, having same properties.
3. Which element has:
4. (a) What property do all elements in the same column of the Periodic Table as boron have in common?
(b) What property do all elements in the same column of the Periodic Table as fluorine have in common?
Ans. (a) Elements in the same column or group as boron have valency of three and have three valence electrons.
(b) Elements in the same column or group as fluorine form acidic oxides and have seven electrons in their outermost shells and have valency of one.
5. An atom has electronic configuration 2, 8, 7.
6. The positions of three elements A, B and C in the periodic table are shown below:
(a) State whether A is a metal or non-metal.
|Group 16||Group 17|
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 ?
Nitrogen will be more electronegative because outermost shell is nearer to nucleus and therefore nucleus will attract electrons more strongly. In a group of the periodic table, electron attracting tendency decreases as we move from top to bottom.
8. How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
Ans. Modern periodic table is based on the atomic number and atomic number is directly related to the electronic configuration. One can find the group number and period number of an element on the basis of electronic configuration. For example, if an element has 1 or 2 electrons in its outermost shell, then it would belong to group 1 or group 2. And if it has 3 or more electrons in its outermost shell, then it would belong to group 10, 4-the number of electrons in the outermost shell.
All the alkali metals have one electron in their outermost shell, so they are placed in group 1. Thus, all the group 2 elements have 2 electrons in their outermost shell. In group 15 elements, there are 5 electrons in their outermost shell. Similarly, the number of shells in an element indicates its period number. For example, the atomic number of magnesium is 12 and its electronic configuration is 2, 8, 2. Thus it is an element of 3rd period.
9. In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic number 12, 19, 21 and 38. Which of these have physical and chemical properties resembling calcium?
10. Compare and contrast the arrangement of elements in Mendeleev’s Periodic Table and the Modern Periodic Table.
|Mendeleev’s Periodic Table||Modern Periodic Table|
|(1) Elements are arranged in the order of increasing atomic mass.||Elements are arranged in the order of increasing atomic number.|
|(2) It contain 8 groups and 6 periods.||It contain 18 groups and 7 periods.|
|(3) There is no place for noble gases.||Noble gases are placed on the right hand side of the table.|
|(4) There is no place for isotopes.||Isotopes are kept at the same place because their atomic number is same.|
|(5) Transition elements are placed together in group VIII.||Transition elements are placed in the middle of the long period (Group 3 to 12).|
|(6) Dissimilar metals are placed together.||Dissimilar metals are placed in different groups.|
Key Features of NCERT Solutions for Class 10 Science Chapter 5 Periodic Classification of Elements
The NCERT Solutions for Class 10 are created to help students prepare for their CBSE exams in a comprehensive manner. Here are some key features of the solutions for Class 10 Science:
- The NCERT Solutions for Class 10 Science are designed by the CBSE syllabus and mark distribution.
- Detailed answers are provided to help students understand the subject matter better.
- Step-by-step explanations are given for the questions in each chapter.
- Using clear and logical language helps build students' confidence in the subject.
- Visual aids enhance understanding and facilitate faster absorption of the topics.
FAQs on NCERT Solutions for Class 10 Science Chapter 5 Periodic Classification of Elements
Ans: The topic of Mendeleev’s Periodic Table covered in Chapter 5 of NCERT Solutions for Class 10 Science includes the following points:
- Elements are arranged in increasing order of their atomic masses.
- Eight groups are present.
- Each group is subdivided into subgroups ‘a’ and ‘b’
- Noble gases were not discovered at that time, so the groups for noble gases were not present.
- Isotopes have no place in this periodic table.
Ans: The NCERT Solutions for Class 10 Science Chapter 5 are created according to the CBSE blueprint with chapter-wise marks distribution. They provide elaborated solutions, step-by-step explanations for numerical problems, simplified and logical language, and pictorial representations to enhance understanding and boost confidence.
Ans: Chapter 5, Periodic Classification of Elements, includes exercises about three different periodic tables. It begins with classifying elements based on their properties and then explains Dobereiner’s triad and its concept. The chapter also covers Newland’s Law of Octaves, Mendeleev’s periodic table, and the modern periodic table with the classification of elements.