The ACS Style Guide is the definitive source for proper ACS citation style:
Coghill, Anne M.; Garson, Lorrin R. Eds. The ACS Style Guide: Effective Communication of Scientific Information, 3rd ed.; ACS: Washington, 2006.
It is available in the Reference Collection in the Davis Centre Library (QD8.5.A25 2006).
Most research builds on previous research. When people read an essay we've written, they want to know where we got our information or they might want to do some research of their own on the topic. For that reason, we provide details on the information we've used—it helps readers find that information on their own. Moreover, it is simply ethical and courteous to acknowledge where our ideas came from. Failure to do so—plagiarism, in other words—can have serious consequences, including course failure and even expulsion from the university.
To acknowledge someone's work, you cite that work. This means that you give information about the work in your bibliography. A style guide describes a specific format for citing material, to which you have referred to in your work. Certain disciplines prefer certain styles. For example, chemistry students will most often be required to use the American Chemical Society (ACS) style.
If you need help learning the art of scientific writing (papers, presentations or posters) then try the following resources.