-------+-----------+
1 | | | | |
2 |N=14.04 |O=16 |F=19 | |
--------+-----------+-----------+-----------+-----------+
3 | P=31| S=32.06| Cl=35.45| |
--------+-----------+-----------+-----------+-----------+
4 |V=51.2 |Cr=52.1 |Mn=55 |Fe=55.9 |
| | | |Ni=58.7 |
| | | |Co=59 |
--------+-----------+-----------+-----------+-----------+
5 | As=75| Se=79.2| Br=79.96| |
--------+-----------+-----------+-----------+-----------+
6 |Cb=94 |Mo=96 | |Ru=101.7 |
| | | |Rh=103 |
| | | |Pd=106.5 |
--------+-----------+-----------+-----------+-----------+
7 | Sb=120.2| Te=127.6| I=126.97| |
--------+-----------+-----------+-----------+-----------+
8 |Ta=183 |W=184 | |Os=191 |
| | | |Ir=193 |
| | | |Pt=194.8 |
--------+-----------+-----------+-----------+-----------+
9 | | | | |
--------+-----------+-----------+-----------+-----------+
10 | U=238.5 | | | |
--------+-----------+-----------+-----------+-----------+
| R_{2}O_{5}| RO_{3} | R_{2}O_{7}| RO_{4} |
| RH_{3} | RH_{2} | RH | |
--------+-----------+-----------+-----------+-----------+

[* This includes a number of elements whose atomic weights lie
between 140 and 173, but which have not been accurately studied, and
so their proper arrangement is uncertain.]

~Place of the atmospheric elements.~ When argon was discovered it was seen
at once that there was no place in the table for an element of atomic
weight approximately 40. When the other inactive elements were found,
however, it became apparent that they form a group just preceding Group
1. They are accordingly arranged in this way in Group 0 (see table on
opposite page). A study of this table brings to light certain very
striking facts.

~Properties of elements vary with atomic weights.~ There is evidently a
close relation between the properties of an element and its atomic
weight. Lithium, at the beginning of the first group,