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1.why transition metals and their compounds act as a catalyst?

2.The outer electronic configurations of two members of the lanthanide series as follows:4f15d16s2 and 4f75d06s2.what are their atomic numbers?predict the oxidation states exhibited by these elements in their compounds?

Transition elements: Those elements have incompletely filled d-orbitals.

  • Transition elements act as good catalyst in chemical reaction. The most important reason transition metals are good catalysts is that they can lend electrons or withdraw electrons from the reagent, depending on the nature of the reaction. The ability of transition metals to be in a variety of oxidation states, the ability to interchange between the oxidation states and the ability to form complexes with the reagents and be a good source for electrons make transition metals good catalysts.
  • Cerium element has electronic configuration [Xe] 4f1 5d1 6S2. Atomic number of Cerium is 58. It shows +3 and +4 oxidation states.
  • Europium has electronic configuration [Xe] 4f7 5d0 6S2. Atomic number of Europium is 63. It shows +2 and +3 oxidation states.

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Transition metals are any of various metallic elements such as chromium, iron and nickel that have valence electrons in two shells instead of only one. A valence electron refers to a single electron that is responsible for the chemical properties of the atom. Transition metals are good metal catalysts because they easily lend and take electrons from other molecules.

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1. Transition elements act as good catalysts:

(i) Due their variable oxidation states, they form intermediate complexes, thereby providing a new path for the reaction with lower oxidation state,

(ii) They provide a surface for the reaction, to occur.

2. Note: 3d series means it has [Ar] core (ie, all 3d element have 1s2 2s2 2p6 3s2 3p6 as common configuartion)

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 2. So 5d series (ie, lanthanoids, included) have common [Xe] core {atomic number of Xenon is 54}

so: [Xe] 4f1 5d1 6s2 means 54 + 1 + 1 + 2 = 58.

Hence, the element is Cerium and Ce4+ is its stable oxidation state (as it will attain the noble gas configuraton).

Similarly,

[Xe] 4f7 5d0 6s2 means 54 + 7 + 0 + 2 = 63.

Thus, the element is Europium and Eu2+ is its stable oxidation state (due to its half - filled  f - orbital).

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1. Transition elements act as good catalysts:

(i) Due their variable oxidation states, they form intermediate complexes, thereby providing a new path for the reaction with lower oxidation state,

(ii) They provide a surface for the reaction, to occur.

2. Note: 3d series means it has [Ar] core (ie, all 3d element have 1s2 2s2 2p6 3s2 3p6 as common configuartion).

Thus, 5d series (ie, lanthanoids, included) have common [Xe] core {atomic number of Xenon is 54}

so: [Xe] 4f1 5d1 6s2 means 54 + 1 + 1 + 2 = 58.

Hence, the element is Cerium and Ce4+ is its stable oxidation state (as it will attain the noble gas configuraton).

Similarly,

[Xe] 4f7 5d0 6s2 means 54 + 7 + 0 + 2 = 63.

Thus, the element is Europium and Eu2+ is its stable oxidation state (due to its half - filled f - orbital).

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