Question

What fact about elements would help explain why two elements would bond with the same element in the same proportion?

Answer 1

The elements are found in the same column on the periodic table.

Answer 2

Their electronic configuration.

Step-by-step explanation:

Atomic propreties can be undestood upon analisis of its electronic configuration, because the way that electrons fill up the atomic orbitals will determine its reactivity.

So, if element X when combined with Y or Z givez XY or XZ it means that Y and Z must have the same electronic configuration.

The periodic table is made in a way that atoms with the same electronic configuration are at the same group, so Y and Z must be at the same group as well.