I sometimes do an ethics workshop with our summer research students and I share with them the American Chemical Society's "Code of Conduct" https://www.acs.org/careers/career-services/ethics/the-chemical-professionals-code-of-conduct.html

I'm not sure if it's the kind of thing you're looking for and I've never used it in a class, but it is "ours." And it looks like it's been updated recently.

I've never done this, but the question gave me the idea...what about trying to begin with a discussion (perhaps prompted by a reading, perhaps not), in which the students try to generate a list of the key characteristics of honorable and ethical scientific conduct? I would be curious to see first whether their list matched my own, but second to see what aspects of "being a scientist" perhaps come naturally to them at that point in their careers, and what aspects are things which they absorb late in their education. 

Of course, if they generate it, they will also feel a greater obligation to uphold it (ownership) and will see it as less of a set of externally imposed rules for your benefit, and more of an internally generated rule-set for their own benefit.

I also wanted to add that my favorite resource for teaching ethics in chemistry is Jeff Kovac's book: The Ethical Chemist: Professionalism and Ethics in Science. It has a lot of great case studies for students to work through.

 The ACS has a document on teaching ethics called "Supplement on the Teaching of Professional Ethics," which you can find at https://www.acs.org/content/dam/acsorg/about/governance/committees/trai…

The ACS has a bunch of additional resources at:

http://portal.acs.org/portal/acs/corg/content?_nfpb=true&_pageLabel=PP_…;

And more cases can be found at this National Academy of Engineering site:

https://onlineethics.org/taxonomy/term/1891

I agree with Joanne that the ACS Code is a good place to start. When I used to teach my department's Literature and Seminar course (which had a multi-week unit on ethics), I used to have students read "codes of conducts" from several different scientific societies such as ACS, Sigma Xi, APS, ASM, etc. An interesting activity might be to have your students construct their own code based on the codes of other scientific societies. Another engaging way to introduce codes of condut is to give students a C&EN article about a misconduct case (such as H. Schon at Bell labs, 2002), have a discussion, and then formulate a code of ethics.  My students have always been fascinated by these stories - they're real attention grabbers.

I'm also a huge fan of the Jeff Kovac book that Joanne referenced. We've had our students role play these scenarios (and others from a book put out by one of the Microbiology societies).  They really get into this. 

I do a very similar thing in my senior seminar course.  That's how we start out the unit, in fact.  Students generally immediately list values like integrity and honesty (and this leads to excellent discussions on what these words mean in context).  It takes them a while, but they also eventually list less "obvious" values, that maybe have less to do with being an ethical scientist, per se, and more to do with being the kind of colleague that others will enjoy working with and learning from.  One student (unprompted!) listed "generosity of spirit" as a key quality of being a scientist.  I liked that!

The assignment I use (though I might modify it somewhat this spring) for ethics in my senior seminar course is in the General Teaching Resources content area of VIPEr.  I think the most valuable part of our discussions is talking about why "doing the right thing" is sometimes hard.  Students seem to "get" why you're not supposed to lie or make up data or take someones idea, but they have usually not thought through the fact the pressures increase, not decrease, in grad school and beyond.