The outer electronic configurations of two members of the lanthanoid series are as follow: `4f^(1) 5d^(1)` and `4f^(7) 5d^(0) 6s^(2)`. Whataretheir atomic numbers? Predict the oxidation states exhibited by these elements in their compounds.

Name the members of the lanthanoid series which exhibit + 4 oxidation states and those which exhibit +2 oxidation states. Try to correlate this type of behaviour with the electronic configuration of these elements.

Which elements has electronic configuration 1s^2 2s^ 3s^2 3p^6 4s^2 ?

Which is more stable configuration and why ? 4s^2 3d^9 and 4S^1 4s^10

The electronic configuration of an atom is 1s^2 2s^2 2p^6 3s^2 . Determine its atomic number. How many neutrons are present in the nucleus if its atomic weight is 24.

If the nitrogen atom had electronic configuration is 1s^7 , it would have energy lower than that of the normal ground state configuration 1s^2 2s^2 2p^3 because the electrons would be closer to the nucleus. Yet 1s^7 is not observed. It violates:

The co-ordination number and oxidation number of X in the following compound [X(SO_4)(NH_3)_5]C1 will be: