Arrange the elements in each of the following groups in order of increasing ionization energy:

(a) Li, Na, K
Order: K < Na < Li.
Ionization energy decreases as you move down the group because atomic size increases, and the outermost electron is farther from the nucleus, experiencing less attraction.

(b) Cl, Br, I
Order: I < Br < Cl.
Ionization energy decreases as you go down the group because the atomic size increases, and the outermost electron is further from the nucleus.

Related Questions:

  1. Explain why Na has higher ionization energy than K.
  2. Write the valence shell electronic configuration of an element present in the 3rd period and Group IIA.
  3. Define halogens.
  4. Which atom has a higher shielding effect, Li or Na?
  5. Alkali metals belong to the S-block in the periodic table. Why?
  6. Why does atomic radius decrease across a period from left to right?
  7. Why do noble gases have high ionization energy?
  8. Why are alkali metals highly reactive?
  9. What is periodicity in the periodic table?
  10. Differentiate between a period and a group in the periodic table.
  11. Arrange the elements in each of the following in order of decreasing shielding effect:
  12. Specify which of the following elements you would expect to have the greatest electron affinity: S, P, Cl
  13. Electronic configurations of some elements are given below. Group the elements in pairs that would represent similar chemical properties:
  14. Arrange the elements in groups and periods from Q. No. 6:
  15. For normal elements, the number of valence electrons of an element is equal to the group number. Find the group number of the following elements:
  16. Write the valence shell electronic configuration for the following groups:
  17. Write the valence shell electronic configuration of the atoms of the following elements:
  18. In which block, group, and period in the periodic table would you place each of the following elements with the given electronic configurations?
  19. Explain the trends of atomic size, ionization energy, and electron affinity in the periodic table with suitable examples.
  20. Explain the position and properties of alkali metals and halogens in the periodic table. Why do they react so easily with each other?