Why is the symbol for protactinium pa?

Answer 1

The chemical symbol for protactinium is Pa because Pr, Po, and Pt were already taken.

Protactinium was discovered in 1913. Praseodymium (Pr, discovered in 1885), polonium (Po, discovered in 1898), and platinum (Pt, known at least since the 1500s) were already discovered and named. The symbol Pa uses the first unused letter (a) in protactinium's name.

Answer 2

The symbol for protactinium is Pa because it comes from the first two letters of its name, "proto-" and "-actinium". The convention for elements’ symbols is to use one or two letters that correspond to the element’s name in Latin or English.