3. Electron Configuration and Periodic Properties
   
   1. Of the elements Li, O, C and F, identify the one with the largest atomic radius and the one with the smallest atomic radius.
      
   2. Of the elements Br, At, F, I and Cl, identify the one with the smallest atomic radius and the one with the largest atomic radius.
      
   3. Consider the four hypothetical main group elements Q, R, T and X with the outer electron configurations indicated below. Then answer the questions that follow.
      Q: 3s ² 3p ⁵
      R: 3s ¹
      T: 5s ² 4d ¹⁰ 5p ⁵
      X: 5s ² 4d ¹⁰ 5p ¹
      
      a) Identify the block locationof each hypothetical main group element.
      b) Which of these elements are in the same period?
      c) Which of these elements are in the same group?
      d) Which element would you expect to have thehighest first ionization energy?
      e) Which element would have the lowest first ionization energy?
      f) Which element would you expect to have the highest second ionization energy?
      g) Which of the elements is most likely to form a 1+ ion?
      
   4. Consider the five hypothetical main group element E, G, J, L and M with the outer electron configurations shown below.
      E: 2s ² 2p ⁵
      G: 5s ² 4d ¹⁰ 5p ⁵
      J: 2s ² 2p ²
      L: 6s ² 5d ¹⁰ 6p ⁵
      M: 2s ² 2p ⁴
      
      a) Identify the block location for each element.
      b) Indicate which elements are in the same period.
      c) Indicate which elements are in the same group.
      d) Which element would you expect to have the highest electron affinity?
      e) Which would you expect to from a 1- ion?
      f) Which should have the highest electronegativity?
      g) Compare the ionic radius of the typical ion formed by the element G with the radius of its neutral atom.
      h) Which element(s) contains seven valence electrons?
      
   5. State the general period and group trends among main group elements with respect to each of the following properties:
      a) atomic radii
      b) first ionization energy
      c) electron affinity
      d) ionic radii
      e) electronegativity
      
   6. Among the main group elements, what is the relationship between group number and the number of valence electrons among group members?
      
   7. a) How do the first ionization energies of main group elements vary across a period and down a group?
      b) Explain the basis for the trends.
      
   8. a) What signs are associated with electron affinity values, and
      b) What is the significance of each sign?
      
   9. For each of the following groups, indicate whether electrons are more likely to be lost or gained in compound formation and give the number of such electrons typically involved:
      a) Group 1
      b) Group 2
      c) Group 13
      d) Group 16
      e) Group 17
      f) Group 18
      
   10. Why is fluorine special in terms of electronegativity?
       

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