Source : Webster's Revised Unabridged Dictionary (1913)
TABLE OF THE PERIODIC LAW OF THE CHEMICAL ELEMENTS (The vertical
columns contain the periodic groups) Series1[ 2[ 3[ 4[ 5[ 6[ 7[
8[ 9[ 10[ 11[ 12[
--------------------------------------------------------------
|I. II. III. IV. V. VI. VII. VIII. | RH4 RH3 RH3 RH |R2O RO R3O3
RO2 R2O5 RO3 R2O7 RO4
-------------------------------------------------------------- H
1 Li 7 Na 23 K 39 (Cu) 63 Rb 85.2 (Ag) (108) Cs 133 (-) (-) (Au)
(197) (-)
---------------------------------------------------------------
Note: A similar relation had been enunciated in a crude way
by Newlands; but the law in its effective form was
developed and elaborated by Mendelejeff, whence it is
sometimes called {Mendelejeff's law}. Important
extensions of it were also made by L. Meyer. By this
means Mendelejeff predicted with remarkable accuracy
the hypothetical elements ekaboron, ekaluminium, and
ekasilicon, afterwards discovered and named
respectively scandium, gallium, and germanium.
{Periodic star} (Astron.), a variable star whose changes of
brightness recur at fixed periods.
{Periodic time of a heavenly body} (Astron.), the time of a
complete revolution of the body about the sun, or of a
satellite about its primary.