The document discusses electron affinity, defined as the energy change when an electron is added to a neutral atom to form a negative ion. It outlines factors affecting electron affinity including nuclear charge, atomic size, and electron configuration, noting that electron affinity generally increases across a period and decreases down a group. Additionally, it describes how electron affinity is often an exothermic process and can be analyzed using the Born-Haber cycle.

1. CHEMISTRY
PRESENTATION
TOPIC -: ELCTRON AFFINITY AND ITS TRENDS
SUBMITTED TO -: Ms. JAYSREE VISHWAS

2. ELECTRON AFFINITY
 Energy that occur when an electron is added to a
neutral atom in the gaseous state to form a
negative ion.
X(g) + e- ---- X.(g)
E = electron attachment energy
Electron affinity = - E (electron attachment)

3. SECOND ELECTRON AFFINITY :-
 Second electron affinity of n element M(g) is
defined as the amount of energy required to add
one more electron to its mononegative anion,to
form dinegative anion.
The addition of second electron to uni-
negative ion is an endothermic process

4. Factors Affecting Electron Affinity :
 Nuclear Charge :
More the nuclear charge of the atom more
strongly will it attract additional electron. Therefore, electron affinity
increases as the nuclear charge increases.
 Atomic Size :
The smaller the size of atom smaller will be the
distance between the extra electron and the nucleus. Therefore,
electrostatic force of attraction will be more and the electron affinity
will be higher.
 Electron Configuration :
Atoms having stable electronic configuration (i.e.
those having completely filled or half filled outer orbitals) do not show
much tendency to add extra electron, so have either zero or very low
electron affinities.

5. Periodic Trends :
 Electron affinity values generally increases on moving left to right in
a period.
 Electron affinities undergo a general decrease down a group.
 Electron affinity is usually exothermic.
 Electron affinities can be obtained by using Born-Haber cycle.

6.  In general, electron
affinity becomes more
exothermic as you go
from left to right across
a row.
 The first occurs
between Groups IA
and IIA.
I. Added electron
must go in p-
orbital , not s-
orbital.
II. Electron is farther
from nucleus and
feels repulsion
from s-electrons.

7. THANK YOU
SUBMITTED BY : NABEEL KHAN