Robert is studying a substance that is a made out of one element this means that

it means that Robert is studying a simple substance.

Explanation:

A simple substance can be a raw material, an atom, or an chemical element. It is an exhaustive investigation of only one element that is part of all the study subject. It’s important that when someone study only an element know that it can be a potencial part of a big factor, to be a gratest function inside the world.

responsibilities im assuming

an informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.