Among the following, the isoelectronic specie (s) is/are
(i) O2-, F-, Na+, Mg2+
(ii) Na+, Mg+, Al3+, F-
(iii) N3-, O2-, F-, Ne
(i) and (ii)
(i), (ii) and (iii)
(ii) and (iii)
(i) and (iii)
D.
(i) and (iii)
lsoelectronic species are elements or ions that have the same, or equal number of electrons. Hence, O2-, F-, Na+, Mg2+, Ne, N3-, Al3+ are isoelectronic species. But Mg+ is not isoelectronic with respect to other species.
The size of the iso-electronic species Cl-, Ar and Ca2+ is affected by:
nuclear charge
Prinicpal quantum number of valence shell
azimuthal quantum number of valence shell
electron-electron interaction in the outer orbitals
The equation used to represents the electron gain enthalpy is
X(g) + e- → X-(g)
X(s) + e- → X-(g)
X(g) → X+(g) + e-
X(s) → X+(g) + e-
An element in +2 oxidation state has 24 electrons. The atomic number of the element and the number of unpaired electrons in it respectively are
24 and 4
26 and 4
24 and 2
26 and 5
The electronic configuration of Eu (Atomic no.63), Gd (Atomic no. 64) and Tb (Atomic no. 65) are
[Xe]4f6 5d1 6s2, [Xe] 4f7 5d1 6s2 and [Xe] 4f9 6s2
[Xe] 4f6 5d1 6s2 , [Xe] 4f7 5d1 6s2 and [Xe] 4f8 5d1 6s2
[Xe] 4f7 6s2, [Xe] 4f7 5d1 6s2 and [Xe] 4f9 6s2
[Xe] 4f7 6s2, [Xe] 4f7 5d1 6s2 and [Xe] 4f9 6s2
The increasing order of the first ionisation enthalpies of the elements B, P, S and F is
B < S < P < F
F < S < P < B
P < S < B < F
B < P < S < F
The element having greatest difference between its first and second ionization energies, is
K
Ca
Ba
Sc
The electronic configuration of 59Pr ( praseodimium) is
[54Xe] 4f25d16s2
[54Xe] 4f15d16s2
[54Xe] 4f36s2
[54Xe] 4f35d2