Explanation
Order of first ionisation potential
Na<Mg<Al<Si
Mg has extra stability than Al due to fully filled 3s-Orbital
Order of electron gain enthalapy
O<S<F<U
Order of ionisation enthalapy
F<O<N
On moving left to right in a period ionisation enthalapy increases.
Atomic no. of element B = Z
(B is a noble gas)
Atomic no. of A = Z = 1
So, A is halogen
Atomic no. of C = Z+1
It belongs to group IA. C must be an alkali metal.
Atomic no. of D = Z+2
It belongs to group II A. D must be alkaline earth metal.
Order of ionisation energy
N>0
Due to presence of half filled p-orbital in nitrogen.
Ionisation energy values for the removal of valence electrons in comparision to remove electrons from inner shell is very high. Since there is large difference between IE4 and IE5. So atom X has four valence electrons.
The physical and chemical properties of elements are periodic function of their electronic configuration. So it is correct statement.
In alkali metals, reactivity increases down the group as electropositivity increases but for halogen reactivity decreases down the group as molecular stability of halogen increases.
Amongst F, S, Fe, Be; Fe is most metallic and hence has the largest tendency to lose electrons.
Ionization energy decreases
Extra stability of the exactly half-filled p-orbitals
Just sufficient to cause an electron to escape from the atom
Ionic radius increases
With increase in atomic number, the atomic size increases both in 1st (group 1) and VII group ( group 17).
Elements (a) and (b) are alkali metals whereas (c) and (d) are alkaline earth metals. Amongst alkali and alkaline earth metals, alkali metal with the biggest size is the most electropositive element
Same number of electrons in the outermost shell of their atoms
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