Question

The electron affinity is the energy released when an electron is added to a neutral atom to make a 1- anion. The table below shows the electron affinities for the 2nd period (row) elements. The value reported is the amount of energy released when an electron is added to a neutral atom. If no energy is released the anion is not stable and that is reported. Explain the overall trend of electron affinity increasing as you move left to right across the period. (1 pt) Electron Atom affinity (eV) Li 0.618 Ве not stable 0.278 В 1.262 not stable о 1.461 3.401 F Ne not stable

Answer 1

Atom®	Li	Be	B	C	N	O	F	Ne
Electron Affinity (eV) value®	0.618	Not Stable	0.278	1.262	Not Stable	1.461	3.401	Not Stable

The ground state electronic configuration of the 2^nd Period containing elements present in Modern Periodic Table is given below---

Element	Ground state electronic configuration
Li	1s2 2s1
Be	1s2 2s2
B	1s2 2s22p1
C	1s2 2s22p2
N	1s2 2s22p3
O	1s2 2s22p4
F	1s2 2s22p5
Ne	1s2 2s22p6

In the above electronic configuration it is found that when Li atom accept one extra electron and it accommodate at ‘2s’ orbital and the corresponding electron affinity value for Li + e^- = Li^- is 0.918 eV. As Be atom having closed shell electronic configuration it cannot accommodate the extra electron and hence Be^- is not stable. In case of both B and C atoms they can accept one extra electron and it accommodate at ‘2p’ orbital and the corresponding electron affinity value for B + e^- = B^- and C + e^- = C^- is 0.278 eV and 1.262 eV respectively. Due to the half-filled electronic configuration of ‘2p’ orbital of N atom it is relatively more stable therefore N^- is not stable. In case of both O and F atoms they can accept one extra electron and it accommodate at ‘2p’ orbital and the corresponding electron affinity value for O + e^- = O^- and F + e^- = F^- is 1.461 eV and 3.401 eV respectively. Formation of Ne^- is not possible because Ne having closed shell electronic configuration. So, F have higher electron affinity value compared to other elements present in 2nd period in modern periodic table.