Chemistry Writing Guide
- Writing Assignments
- Discipline-Specific Strategies
- Watch Out for...
- Professor's Comments and Websites
Writing in chemistry is similar to writing in other disciplines in that your paper must have a clear purpose that explains why you are writing, a thesis statement or main idea that defines the problem to be addressed, and background information wherever necessary. In addition, you should include evidence in the form of figures, graphs, and tables to support your argument.
You will be asked to write an abstract -- a single-spaced paragraph summary that briefly states the purpose of the experiment, important results (and how the results were obtained), and conclusions. Ideally, the abstract can be thought of as one or two sentences from each section of the paper that form a cohesive paragraph that summarizes the entire paper. The abstract should be single spaced unless you receive other instructions from your professor.
When writing an abstract, you should avoid too much experimental detail (e.g. concentration of stock solutions used) or preliminary results (i.e. "raw" data). In addition, make certain that the purpose of the experiment is stated clearly and early in the abstract. Ideally, it should be stated in the first or second sentence.
There are six main sections in a chemistry paper: introduction, experimental section, results section, discussion section, conclusion, and list of references. As with most disciplines, the introduction should include your background knowledge of the experiment, including theory and past research, the relevance of your research, and the thesis statement. You may also state in your introduction any general conclusions you discovered, but try to avoid making your introduction longer than a page.
The purpose of the introduction in a chemical journal is to provide (1) a literature review of what has been published on the subject to justify the importance of your research, (2) an explanation of any unusual experimental approaches, and (3) any background information or explanations that will help the reader understand your experiment and your results. Ultimately, the introduction should explain how the experimental approach you chose allows you to find the numerical or qualitative results you are looking for. For example, if you're going to determine if the substance you synthesized is a particular compound by examining its UV-Vis spectrum, you should find in the literature or a reference book the maximum wavelength of the compound and present it in the introduction.
The experimental section focuses on the details of the experiment. Be certain to include enough information so that the reader could repeat the experiment and obtain similar results within the limits of uncertainty. The following should be addressed in this section: treatment of data (e.g. calculations or computations used to generate graphs) and an identification of instruments and sources of materials used (e.g. synthesized within the lab or bought from Aldrich, Sigma, or Fluka). For commercially available equipment, the manufacturer and the model should be mentioned (e.g. JASCO UV-Vis Spectrophotometer).
The results section should include any figures, graphs, and tables that summarize the data. The material in this section should be presented in the order that best defends the thesis and the order in which they will be addressed in the discussion section. The order in which the data was collected is rarely important. For example, just because the data for graph N was collected before that of graph M does not mean that M shouldn't be presented first if it makes the presentation of data more coherent.
In the results section, graphs are usually listed as figures. Tables are numbered and given specific titles (must include concentrations, volumes, etc.), which are placed at the top of the table. Figures (graphs or any other visuals) are numbered and given a caption, not a title. The caption should be several sentences long and explain what the figure is, what result is found from the figure, and the importance of the result. Captions are placed below the figure.
For a results section, the text, tables, and figures should mirror each other. That is, the text must include all of the important information given in the graphs and tables, but in written form. If a table or figure is included in the report, it must be specifically referenced in the text as at the end of this sentence (Table 1). It might also be worthwhile to note that figures and tables are usually submitted to a journal and also to a professor with the tables and figures attached to the end of the report, not interspersed throughout the text. Journals insert your figures and tables according to their page format.
In the discussion section, you should explain your results and observations and illustrate how they support your thesis, discuss any possible sources of error, and suggest potential future research stemming from your results. You may also want to mention any past research in the field that may pertain to your experiment's results.
Something to think about: results and discussion sections are often combined in chemical journals. In that case, each result is presented and then its relevance is explained. If you are writing a results section alone, you should only present, not interpret, your results. For example, a statement like, "The UV-Vis spectrum of the complex showed a peak at 291 nm" is a statement of your numerical result and is appropriate for a results section. A statement like, "The peak at 291 nm indicates that the complex changed conformation" is interpretive and belongs in a discussion section.
Your conclusion should contain a brief summary of the paper and must state important results (e.g. yield of product) and assess the research with respect to the purpose. This section may be combined with the discussion section; that is, the last paragraph of the discussion section may act as a conclusion.
In the reference section you must list all non-original sources used in the paper in the order in which they appear with the appropriate number. Citations should be made according to the format of the journal to which you will submit your paper. For a Swarthmore class, the Journal of the American Chemical Society format is appropriate. Unlike other disciplines, citations in a chemistry paper are usually not in-text or parenthetical, but incorporated using superscripts as at the end of this sentence.1 It is sometimes appropriate in a discussion section to refer to other researchers by name and end the sentence with a reference. For example, "Khmelnitksy, et al. found that trypsin denatures in 2-propanol."2
- Chemistry papers should be written in passive voice (unless you receive other instructions from your professor).
- Abbreviations or acronyms must be explained the first time they are used.
- Figures, graphs, and tables must be titled and referenced in the text.
- References (including textbooks and lab manuals) must be cited and numbered consecutively with the superscript number corresponding to that reference in the reference section of the paper. The use of superscript suffices as the mode of reference because it eliminates the need for in-text citations and footnotes.
I. Organization: As for all lab reports, chemistry reports are very structured and must be highly organized in a logical way. Organization of results is especially important. Your results and discussion sections, as well as tables and figures, should be organized in a way that leads the reader to draw the same conclusion that you did based on your data. Don't just tack on a graph at the end of the paper or arbitrarily put your results into a table. Think about how you can use tables to make comparisons between your data and literature or reference values. Think about the format of your tables and the chronology of your results section. How can you present your results so that the reader is already convinced of your conclusion before you explicitly state it?
II. Repetition: If you've already said it once, or it's already been published somewhere else, don't say it again. You can refer to other parts of your paper instead of repeating explanations or facts. If you've already written an experimental methods section, you've already explained your procedure; there is no need to provide procedural details again when you talk about results. If the procedure you used came from a published article, provide a short summary, explain any alterations, and then give the citation. Also, if you explain someone else's experimental results in the introduction, it is acceptable to write statements like, "As discussed above, Khmelnitsky, et al. found contradictory results" in your results section. Journals have page limits. Repetitious or unnecessary words or figures are unwelcome.
III. Distraction: Remember that the whole point of writing a chemistry paper is to present results and prove your conclusion based on those results. There are a lot of numbers, facts, and procedure information that you can easily get bogged down by. Just remember that ultimately you have to convince the reader that your conclusion is accurate. If you feel overwhelmed by the amount of information you have to include, try making a flow chart that shows the logical progression of your procedure. Or create your figures and tables first, and then use them as an outline or guide to write your results section. Take a look at published articles to get a sense of how others organize papers and what kinds of phrases and sentence structure are useful and accepted.
Courses Taught: General Chemistry, Organic I and II laboratories
Particular stylistic issues you should keep in mind:
"Write as concisely as possible. Know the meanings of the words you use and choose the best word for your purpose."
Grammar/spelling and word choice pet peeves:
- Using "this" and "that' as undefined pronouns
- Using "so" without "that" or "as"
- Misspelling of terms that are presented in the manual