SKT3033_Topic 2 Descriptive Properties for Representative Elements_pptx

Page 14

  • Inert pair effect is the tendency of the two electrons in the outermost atomic s orbital to remain unionized upon the formation of a chemical bond

  • It is exhibited by some heavier nucleus p-block metal elements with common valence electron configuration ns2 np1-6

  • These elements contain inner d or f – electrons

Page 15

  • The tendency of the two s-electrons to stay inert is called the inert pair effect

  • Poor or ineffective shielding of the outermost ns2 electrons by intervening d and f electrons

  • Due to poor shielding effect, the effective nuclear charge on the outermost s-electrons acts strongly and attracts the electrons to bind with the nucleus

  • Consequently, the two s-electrons show less tendency to participate in chemical reactions

Page 16

  • Moving down the group, the stability of elements and compounds changes due to the inert pair effect

  • Examples: C, Si, Ge, Sn, Pb

  • CO is easily oxidized to CO2 (conversion of +2 to +4)

  • Formation of SiCl4 and SiO2

  • SnCl2 is more stable than SnCl4 due to the inert pair effect

Page 17

  • The inert pair effect also causes variety in the oxidation state of elements in the same group

  • The inert ns2 pairs cause the oxidation state to be 2 less than the expected group valence for the heavier elements in Group 13, 14, 15, and 16

  • Examples of oxidation states for elements in Group 13, 14, 15, and 16

Page 18

  • The inert pair effect also influences the oxidizing and reducing properties of compounds

  • +5 oxidation state is less stable