The particular style that your paper should be written in will be determined by your professor, and you should ask him/her or your TA. If a certain style is not specified, it's probably best to choose one you like and be consistent. (If you aren't sure what a citation style is, it is basically the set of rules which determine how the references should look in the text and at the end of your paper.)
Some common scientific styles are CSE (Council of Science Editors) and ACS (American Chemical Society). The library has the guides to these in print in the S&E library.
Other style guides are available as well, such as APA, MLA, etc.
If you want more specific help, please contact me.