9.56. Choose one of the given causes as the best explanation of each of the effe
ID: 717060 • Letter: 9
Question
9.56. Choose one of the given causes as the best explanation of each of the effects listed later. CAUSES: (1) Scandide contraction. (2) Lanthanide contraction. (3) Relativistic i in mass of a valence s electron penetrating a heavy nucleus. (4) Relativistic shielding ofa valence d or felectron by massive s electrons. (5) No special cause needed; this is a normal periodic trend. EFFECTS: (a) Gold has the highest electron affinity of any element other than a halogen. (b) Gold has a +5 oxidation state, higher than is known for Cu or Ag. (c) It took 100 years to discover that the element hafnium is always present in samples of the element zirconium. (d) Gallium is more electronegative than aluminum. (e) Indium is less electronegative than gallium. ncreaseExplanation / Answer
1) scandide contraction -d) Ga is more electronegative than aluminium
this is the effect of completely filled d orbital of 4th period. as due to poor sheilding of d orbital electrons there is increase in electronegativity of gallium.it appears due to the newly appeared filled d orbital.
2) lanthanide contraction - c) it took 100 years to discover that the element hafnium is always present in the sample of the element zirconium.
lanthanide contraction appear after a fully filled f orbital appear first which cause no increase in the in the size of 6th period element of d block compared to corresponding 5th period element. which causes similar properties of elements like Zr and Hf.
3) relativistic increase in the mass of valance s electrons penetrating a heavy nucleus. - b) Gold has +5 oxidation state higher known for Cu and Ag.
in heavy metals the core electron move freely and valnce s electron penetrates in heavy nucleus strongly which give unusual behavior to gold.
4)relativistic shielding of a valance d or f electron by massinve s electrons - a) gold has highest electron affinity of any element other than halogen.
as d and f orbital electron show poor shielding there is an unexpected increase in effective nuclear charge in heavy metals. that is why gold due to its relativistic effects has high electron affinity.
5) No special cause needed , it is a general periodic trend - e) indium is less electronegative than gallium.
electronegativity generally decrease down the group because size of atom increase and z eff . decrease.
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