Periodic classification of elements NCERT Questions

NCERT INTEXT EXERCISE

  1. Did Dobereiner’striads also exist in the columns of Newlands’ Octaves? Compare and find out.
  2. What were the limitations of Dobereiner’s classification?
  3. What were the limitations of Newlands’ Law of Octaves?
  4. 4. Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements:
    K, C, Al, Si, Ba.
  5. 5. Besides gallium, which other elements have since been discovered that were left by Mendeleev in his Periodic Table? (any two)
  6. 6. What were the criteria used by Mendeleev in creating his Periodic Table?
  7. 7. Why do you think the noble gases are placed in a separate group?
  8. 8. How could the Modern Periodic Table remove various anomalies of Mendeleev’s Periodic Table?
  9. 9. Name two elements you would expect to show chemical reactions similar to magnesium. What is the basis for your choice?
  10. 10. Name

(a) three elements that have a single electron in their outermost shells.

(b) two elements that have two electrons in their outermost shells.

(c) three elements with filled outermost shells.

  1. 11. (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?

  1. 12. In the Modern Periodic Table, which are the metals among the first ten elements?
  2. 13. By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristic?

NCERT TEXT BOOK EXERCISE

  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.
  2. Element X forms a chloride with the formula XCl2, 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     (b) Mg              (c) Al               (d) Si

  1. Which element has

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

(b) the electronic configuration 2, 8, 2?

(c) a total of three shells, with four electrons in its valence shell?

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

(e) twice as many electrons in its second shell as in its first shell?

  1. (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?

 

  1. An atom has electronic configuration 2, 8, 7.

(a) What is the atomic number of this element?

(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)

  1. The position of three elements A, B and C in the Periodic Table are shown below −
Group 16 Group 17
− −
− A
− −
B C

(a) State whether A is a metal or non-metal.

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

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

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

  1. 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?
  2. How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
  3. 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?
  4. Compare and contrast the arrangement of elements in Mendeleev’s periodic Table and the Modern Periodic Table.

ADDITIONAL QUESTIONS FOR PRACTICE

  1. In the modern periodic table which are the metals among the first ten elements.
  2. Write two reasons responsible for late discovery of noble gases?
  3. Which of the following statement is not correct statement about the trends when going from left to right across the periods of periodic table?
  4. The element becomes less metallic in nature.
  5. The number of valence electron increase.
  6. The atoms lose their electron more easily
  7. The oxide becomes more acidic
  8. Element X forms a chloride with the formula XCl2 which is solid with a high melting point. X would most likely be in the same group of periodic table as
    (a) Na (b) Mg (c) Al  (d) Si?
  9. The elements Li, Na and K, each having one valence electron, are in period 2, 3 and 4
    respectively of modern periodic table. 3
    (i) In which group of the periodic table should they be?
    (ii) Which one of them is least reactive?
    (iii) Which one of them has the largest atomic radius? Give reason to justify your
    answer in each case.
  10. Given below are some elements of the modern periodic table:

4Be, 9Fe, 14Si, 19K, 20Ca

(i) Select the element that has one electron in the outermost shell and write its electronic configuration.

(ii) Select two elements that belong to the same group. Give reason for your answer.

(iii) Select two elements that belong to the same period. Which one of the two has  bigger atomic size?

  1. State the modern periodic law for classification of elements. How many (i) groups and

(ii) periods are there in the modern periodic table?

  1. An element ‘M’ has atomic number 11.  (a) Write its electronic configuration.  (b) State the group to which ‘M’ belongs. (c) Is ‘M’ a metal or a non-metal. (d) Write the formula of its chloride.
  2. F, Cl and Br are the elements each having seven valence electrons. Which of these (i) has the
    largest atomic radius, (ii) is most reactive? Justify your answer stating reason for each. (3)
  3. Nitrogen(atomic number=7) and phosphorus(atomic number=15) belong to same group-15 of the periodic table. Write the electronic configuration of these two elements. Which of these two will be more electronegative? Why.
  4. In the modern periodic table Ca (At no. = 20) is surrounded by elements with atomic number 12, 19, 21,
    and 38. Which of these have physical and chemical properties resembling Ca.
  5. Did Doberenier‘s triads also exist in the column of Newland octaves. Compare and find out.
  6. What are the limitation of Dobernier‘s classification?
  7. What are the limitations of Newlands law of Octaves
  8. Use Mendeleev‘s periodic table to predict the formula for the oxide of following element K, C, Ba, Al
  9. Besides Ga, which other elements have been discovered that were left by Mendeleev in his periodic table (Any two)?
  10. What were the criteria used by Mendeleev in creating his periodic table?
  11. Why do you think the noble gases are placed in a separate group?
  12. Name two elements you would expect to show chemical reaction, similar to magnesium. What is the basis for your choice?
  13. (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?

  1. An atom has electronic configuration 2,8,7

(a) What is the atomic no. of this element?

(b) To which of the following elements would it be chemically similar N(7) F(9) P(15) Ar(18)

  1. How does the electronic configuration of an atom relate to its position in the Modern periodic table?

 

  1. How could the modern periodic table remove various anomalies of Mendeleev‘s periodic table?
  2. Name

(1) three elements that have a single electron in their outermost shells.

(2) two elements that have two electrons in their outermost shells.

(3) three elements with filled outermost shell.

  1. (a)Li, Na ,K are all metals that react with water to liberate H2 gas .Is there any similarity in the atoms of these elements.

(b)Helium is an unreactive gas and Neon gas is a gas of extremely low reactivity, what do their atoms have in common.

  1. The position of three elements A, B and C in the periodic table are shown below

Group-16                    Group-17

–                                  –

–                                  A

–                                  –

B                                C

(a) state whether A is a metal or non-metals .

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

(c) will C be larger or smaller in size then B.

(d) which type of ion, cation or anion will be formed by element A

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