What is the valency of platinum?

Platinum can have 1-3 valence electrons, as it is in the transition metals group.

All elements within the transition metals group do not have specific valency. However, for the other groups, there is a fixed valency that those elements may have.

The first column/group, known as the alkali metals group, will always have 1 valence electron, and will be attracted to elements that have 7 valence electrons. When they group together, they complete the 8 max valence electrons.

The second column/group, known as the alkali-earth metals group, will always have 2 valence electrons, and be attracted to elements that have 6 valence electrons.

Elements in the third group will always have 3 valence electrons, thereby attracting to elements with 5 valence electrons.

The fourth group will have elements with 4 valence electrons, fifth group 5 valence electrons, sixth group 6 valence electrons, seventh group 7 valence electrons, and eighth group 8 valence electrons.