Ionisation energy in group 1A varies in the decreasing order as
Li > Na > K > Cs
Na > Li > K > Cs
Li > Cs > K Na
K > Cs > Na > Li
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
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 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 electronic configuration of 59Pr ( praseodimium) is
[54Xe] 4f25d16s2
[54Xe] 4f15d16s2
[54Xe] 4f36s2
[54Xe] 4f35d2
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