Which characteristic gives the most information about what kind of element an atom is ?

The atomic number

Explanation:

igneous rocks also form where plates converge. the subducting plate melts as it sinks into the crust of the earth, and the melt rises into the overriding plate forming volcanoes. metamorphic rocks are formed mainly in the lithosphere, wherever there is high pressure and high temperature. -woods

e/c, where e is its total energy