Periodic Table Arrangement
The periodic table is not arranged in the order of increasing relative molecular mass. Instead, it is arranged in the order of increasing atomic number. Here's how it works:

Atomic Number
- The atomic number of an element is the number of protons in the nucleus of an atom.
- Elements are arranged in the periodic table according to their atomic number, from left to right and top to bottom.
- This arrangement allows elements with similar chemical properties to be grouped together in columns called groups.

Periods and Groups
- The periodic table is organized into periods (rows) and groups (columns).
- Elements in the same group have similar chemical properties because they have the same number of electrons in their outermost energy level.
- Elements in the same period have their electrons in the same energy level.

Increasing Relative Molecular Mass
- While elements in the same group may have similar chemical properties, they do not necessarily have increasing relative molecular mass from left to right.
- The relative molecular mass of an element is determined by the sum of the atomic masses of its atoms in a molecule.
- The periodic table does not follow a pattern of increasing relative molecular mass across periods or groups, as it is based on atomic number.
In conclusion, the periodic table is arranged in the order of increasing atomic number, not increasing relative molecular mass. This organization helps chemists predict the properties of elements and their compounds based on their atomic structure.