Chemistry · Textbook solutions

Modern Periodic Table

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. · 41 questions

7. Modern Periodic Table — worked examples

9 q

Solved Problems 7.1 – 7.9

Worked · 9
  1. Solved Ex.7.1
    What is the subshell in which the last electron of the first element in the 6th period enters ?
  2. Solved Ex.7.2
    How many elements are present in the 6th period? Explain.
  3. Solved Ex.7.3
    Outer electronic configurations of a few elements are given below. Explain them and identify the period, group and block in the periodic table to which they belong. 2He:1s2{}_{2}\mathrm{He} : 1s^2, 54Xe:5s25p6{}_{54}\mathrm{Xe} : 5s^2 5p^6, 16S:3s23p4{}_{16}\mathrm{S} : 3s^2 3p^4, 79Au:6s15d10{}_{79}\mathrm{Au} : 6s^1 5d^{10}
  4. Solved Ex.7.4
    Chlorides of two metals are common laboratory chemicals and both are colourless. One of the metals reacts vigorously with water while the other reacts slowly. Place the two metals in the appropriate block in the periodic table. justify your answer.
  5. Solved Ex.7.5
    Identify the species having larger radius from the following pairs : (i) Na\mathrm{Na} and Na⊕\mathrm{Na^{\oplus}}, (ii) Na⊕\mathrm{Na^{\oplus}} and Mg2⊕\mathrm{Mg^{2\oplus}}
  6. Solved Ex.7.6
    The first ionization enthalpy values of Si\mathrm{Si}, P\mathrm{P} and Cl\mathrm{Cl} are 780, 1060 and 1255 kJ mol−1\mathrm{kJ\ mol^{-1}} respectively. Predict whether the first ionization enthalpy of S\mathrm{S} will be closer to 1000 or 1200 kJ mol−1\mathrm{kJ\ mol^{-1}}.
  7. Solved Ex.7.7
    Identify the element with more negative value of electron gain enthalpy from the following pairs. Justify. (i) Cl\mathrm{Cl} and Br\mathrm{Br} (ii) F\mathrm{F} and O\mathrm{O}
  8. Solved Ex.7.8
    Ge\mathrm{Ge}, S\mathrm{S} and Br\mathrm{Br} belong to the groups 14, 16 and 17, respectively. Predict the empirical formulae of the compounds those can be formed by (i) Ge\mathrm{Ge} and S\mathrm{S}, (i) Ge\mathrm{Ge} and Br\mathrm{Br}.
  9. Solved Ex.7.9
    Write the chemical equations for reaction, if any, of (i) Na2O\mathrm{Na_2O} and (ii) Al2O3\mathrm{Al_2O_3} with HCl\mathrm{HCl} and NaOH\mathrm{NaOH} both. Correlate this with the position of Na\mathrm{Na} and Al\mathrm{Al} in the periodic table, and infer whether the oxides are basic, acidic or amphoteric.

Exercises

32 q

1. Explain the following

Practice · 5
  1. Explain the following
    Ex Q.1 (A)
    The elements Li\mathrm{Li}, B\mathrm{B}, C\mathrm{C}, Be\mathrm{Be} and N\mathrm{N} have the electronegativities 1.0, 2.0, 1.5 and 3.0, respectively on the Pauling scale.
  2. Ex Q.1 (B)
    The atomic radii of Cl\mathrm{Cl}, I\mathrm{I} and Br\mathrm{Br} are 99, 133 and 114 pm, respectively.
  3. Ex Q.1 (C)
    The ionic radii of F⊖\mathrm{F^{\ominus}} and Na⊕\mathrm{Na^{\oplus}} are 133 and 98 pm, respectively.
  4. Ex Q.1 (D)
    13Al{}_{13}\mathrm{Al} is a metal, 14Si{}_{14}\mathrm{Si} is a metalloid and 15P{}_{15}\mathrm{P} is a nonmetal.
  5. Ex Q.1 (E)
    Cu\mathrm{Cu} forms coloured salts while Zn\mathrm{Zn} forms colourless salts.

2. Write the outer electronic configuration of the following using orbital notation method. Justify.

Practice · 3
  1. Write the outer electronic configuration of the following using orbital notation method. Justify.
    Ex Q.2 (A)
    Ge\mathrm{Ge} (belongs to period 4 and group 14)
  2. Ex Q.2 (B)
    Po\mathrm{Po} (belongs to period 6 and group 16)
  3. Ex Q.2 (C)
    Cu\mathrm{Cu} (belongs to period 4 and group 11)

3. Answer the following

Practice · 6
  1. Answer the following
    Ex Q.3 (A)
    La\mathrm{La} belongs to group 3 while Hg\mathrm{Hg} belongs to group 12 and both belong to period 6 of the periodic table. Write down the general outer electronic configuration of the ten elements from La\mathrm{La} to Hg\mathrm{Hg} together using orbital notation method.
  2. Ex Q.3 (B)
    Ionization enthalpy of Li\mathrm{Li} is 520 kJ mol−1\mathrm{kJ\ mol^{-1}} while that of F\mathrm{F} is 1681 kJ mol−1\mathrm{kJ\ mol^{-1}}. Explain.
  3. Ex Q.3 (C)
    Explain the screening effect with a suitable example.
  4. Ex Q.3 (D)
    Why the second ionization enthalpy is greater than the first ionization enthalpy ?
  5. Ex Q.3 (E)
    Why the elements belonging to the same group do have similar chemical properties ?
  6. Ex Q.3 (F)
    Explain : electronegativity and electron gain enthalpy. Which of the two can be measured experimentally?

4. Choose the correct option

Practice · 7
  1. Choose the correct option
    Ex Q.4 (A)
    Consider the elements B\mathrm{B}, Al\mathrm{Al}, Mg\mathrm{Mg} and K\mathrm{K} predict the correct order of metallic character :
    1. A.
      B>Al>Mg>K\mathrm{B} > \mathrm{Al} > \mathrm{Mg} > \mathrm{K}
    2. B.
      Al>Mg>B>K\mathrm{Al} > \mathrm{Mg} > \mathrm{B} > \mathrm{K}
    3. C.
      Mg>Al>K>B\mathrm{Mg} > \mathrm{Al} > \mathrm{K} > \mathrm{B}
    4. D.
      K>Mg>Al>B\mathrm{K} > \mathrm{Mg} > \mathrm{Al} > \mathrm{B}
  2. Ex Q.4 (B)
    In modern periodic table, the period number indicates the :
    1. A.
      atomic number
    2. B.
      atomic mass
    3. C.
      principal quantum number
    4. D.
      azimuthal quantum number
  3. Ex Q.4 (C)
    The lanthanides are placed in the periodic table at
    1. A.
      left hand side
    2. B.
      right hand side
    3. C.
      middle
    4. D.
      bottom
  4. Ex Q.4 (D)
    If the valence shell electronic configuration is ns2np5ns^2 np^5, the element will belong to
    1. A.
      alkali metals
    2. B.
      halogens
    3. C.
      alkaline earth metals
    4. D.
      actinides
  5. Ex Q.4 (E)
    In which group of elements of the modern periodic table are halogen placed ?
    1. A.
      17
    2. B.
      6
    3. C.
      4
    4. D.
      2
  6. Ex Q.4 (F)
    Which of the atomic number represent the s-block elements ?
    1. A.
      7, 15
    2. B.
      3, 12
    3. C.
      6, 14
    4. D.
      9, 17
  7. Ex Q.4 (H)
    Which of the following pair of elements has similar properties ?
    1. A.
      13, 31
    2. B.
      11, 20
    3. C.
      12, 10
    4. D.
      21, 33

5. Answer the following questions

Practice · 11
  1. Answer the following questions
    Ex Q.5 (A)
    The electronic configuration of some elements are given below: a. 1s21s^2 b. 1s22s22p61s^2 2s^2 2p^6 In which group and period of the periodic table they are placed ?
  2. Ex Q.5 (B)
    For each of the following pairs, indicate which of the two species is of large size : a. Fe2+\mathrm{Fe^{2+}} or Fe3+\mathrm{Fe^{3+}} b. Mg2+\mathrm{Mg^{2+}} or Ca2+\mathrm{Ca^{2+}}
  3. Ex Q.5 (C)
    Select the smaller ion form each of the following pairs: a. K+\mathrm{K^+}, Li+\mathrm{Li^+} b. N3−\mathrm{N^{3-}}, F−\mathrm{F^-}
  4. Ex Q.5 (D)
    With the help of diagram answer the questions given below: a. Which atom should have smaller ionization enthalpy, oxygen or sulfur? b. The lithium forms +1 ions while berylium forms +2 ions ?
  5. Ex Q.5 (E)
    Define : a. Ionic radius b. Electronegativity
  6. Ex Q.5 (F)
    Compare chemical properties of metals and non metals.
  7. Ex Q.5 (G)
    What are the valence electrons ? For s-block and p-block elements show that number of valence electrons is equal to its group number.
  8. Ex Q.5 (H)
    Define ionization enthalpy. Name the factors on which ionisation enthalpy depends? How does it vary down the group and across a period?
  9. Ex Q.5 (I)
    How the atomic size vary in a group and across a period? Explain with suitable example.
  10. Ex Q.5 (J)
    Give reasons. a. Alkali metals have low ionization enthalpies. b. Inert gases have exceptionally high ionization enthalpies. c. Fluorine has less electron affinity than chlorine. d. Noble gases possess relatively large atomic size.
  11. Ex Q.5 (K)
    Consider the oxides Li2O\mathrm{Li_2O}, CO2\mathrm{CO_2}, B2O3\mathrm{B_2O_3}. a. Which oxide would you expect to be the most basic? b. Which oxide would be the most acidic? c. Give the formula of an amphoteric oxide.