1.
2020-2021
A SMINAR PRAJENTED BAY - DHARMENDRA
SEM.- 1st
S. P. C. GOVT COLLEGE AJMER
TOPIC- EFFECTIVE ATOMIC NUMBER AND
18 ELECTRON RUAL

2.
Effective Atomic Number
A/C To Sidgwick When ‘CO, Molecules Donate l.p of Electrones
to metal Atome or ion the totel number of Electrones on the
central Atom. Including Accepting Electrones from ‘CO,
molecules is called Effective Atomic number of Metal Atom.It
in many cases ‘ EAN, is equal to the Atomic Number of Sidgwick
And have shown the Following Formula

3.
E.A.N (G)= Xm+2Y/ x = x-1
Where x= no. Of metal atom
y= no.of’ CO, MOLECULES
M= ATOMIC NO. OF METAL
G= ATOMIC NO. OF NEXT INERT GASE
For mononuculer carbonyl’ x , = 1
e.a.n= G= m+2y

4.
Examples:_ 1. Ni(co)4
For ‘ni, m=28
y= 4
E.A.N= 28 + 2×4=36 (kr)

5.
Example:_2. FE(CO)5
For ‘ Fe, Atom
M= 26
y=5
E.A.n=26+2×5=36

6.
E.A.n for polynuclear carbonyl
Ex:_ mn2(Co)10
Electrons from 2 mn Atoms = 2×25 = 50 es.
Electrones from 10 ‘ Co, Molecules = 2× 10 = 20 es.
Electrones from 1 mn-mn Bond = 1×2=2 es.
Totel Electrones = 72 Electrones

7.
Example:_2 . FE3(CO)12
Electrons from 3 ‘fe, Atoms = 3×26= 78
Electrones from 12 ‘ CO,ATOMS = 2×12=24
Electrones from 3 ‘ fe, Bond = 3×2= 6
totel Electrones = 108
E.a.n of fe = 108/3= 36 (kr)

8.
18 Electrones Rule
A/c to this rule sum no. Of outer shell
Electrones the metal atom and no. Of electrons
donated by ‘ Co, Molecules is equal to = 18
1. ex_1. Ni (co)4
For Ni 3d84s2 = 10 electrones
1. ‘CO, ele. 2×4=8 electrones
Totel = 18 elec.

9.
Example – 2 fe(co)5
for fe = 3d64s2 =8
For ‘ Co, ele.= 2×5= 10
totel = 18 Electrones

10.
Thank you……