What if the periodic table starts and ends with triads?

Based on a paper by
Eric Scerri, Department of Chemistry,
University of California at Los Angeles
Los Angeles, CA 90095
scerri@chem.ucla.edu

What is a triad?

Many of the elements can be grouped into groups of three, or triads, based on their chemical properties. When arranged by atomic weight, the second member of each triad is the average of the first and third. This is known as the Law of Triads.

Here is a periodic table arranged with respect to triads.
H, F, Cl are a triad.
He, Ne, Ar are a triad.
Y, Lu, Lr are a triad.

Click on any of these elements for a triad detail page.

H
He
Li
Be










B
C
N
O
F
Ne
Na
Mg










Al
Si
P
S
Cl
Ar
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
Cs
Ba
Lu
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
Fr
Ra
Lr
Rf
Db
Sg
Bh
Hs
Mt
Ds
Rg
Uub
Uut
Uuq
Uup
Uuh