Methods of Calculating Ionization Energies of Multielectron (Five or More) Isoelectronic Atomic Ions
Table 2
Coefficients/constants for calculating ionization energies of multielectron ions.
Screening constants
Coefficient
Coefficient
Reduced mass*
B
3
0.318
0.032
0.999939550
C
3.5
0.572
0.490
0.999954670
N
4
0.842
1.170
0.999961152
O
5
0.716
0.731
0.999966015
F
5.5
1.054
2.357
0.999971388
Ne
6
1.318
3.520
0.999972825
Na
7
2.222
11.809
0.999976377
Mg
7.5
2.344
12.925
0.999977367
Al
8.5
2.882
21.124
0.999979889
Si
9
3.012
22.521
0.999980614
P
9.5
3.194
24.599
0.999982497
S
10.5
2.850
22.194
0.999983051
Cl
11
2.968
23.026
0.999983571
Ar
11.5
3.306
27.683
0.999986454
**
Screening constants
Coefficient
Coefficient
Reduced mass
K
11
2.968
23.026
0.999986113
Ca
11.5
3.306
27.683
0.999986467
Sc
13.5
3.366
30.828
0.999988489
Ti
14
3.832
38.481
0.999989186
V
14.5
4.542
51.618
0.999989405
Cr
15
5.138
62.763
0.999990000
Mn
15.5
5.658
73.472
0.999990188
Fe
16.5
5.850
82.119
0.999990702
Co
17
4.484
57.749
0.999990708
Reduced masses are calculated from atomic number 5 to atomic number 26; for ions above atomic number 26, the reduced mass of atomic 26 is used since the differences between reduced masses at high atomic numbers are too small to show any differences in the calculated results.
**From the potassium series, the constants apply to calculating ionization energies from the third ionization energy (i.e., third ionization of potassium, fourth ionization of calcium, etc.).
