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Overview

This chapter will review the basic writing structures of sentences and paragraphs.

There are different levels of structure in writing. The overall structure of the proposal, article, or thesis (see individual chapters for examples) and structures within the sections e.g., an article introduction has a common structure of broad to narrow. This chapter will discuss sentence and paragraph structure.

Sections in this chapter

• Sentence structure
• Paragraph structure
• Paragraph coherence

Sentence Structure

Sentence Basics

Sentences are arrangements of subjects and objects (nouns), verbs,  and adjectives. Sentences in a scientific paper are on average 25 words, and in a Times Magazine article the average is 17 words.

• Basic: one subject, one verb
• Complex: basic sentences joined with dependent clauses
• Compound: Two or more sentences joined by a conjunction.

There are no set rules around sentence length, but it’s good to keep an eye out for long sentences and vary the length.

Active vs. Passive Voice

In this section, we’ll look at how sentences are structured in active voice and passive voice.

Active voice: A stirring bar mixed the chemicals.

Passive voice: The chemicals were mixed with a stirring bar.

• Subject = stirring bar
• Object = the chemicals
• Verb = mixed
• Auxiliary verb = were
• Preposition = with

In the example above, we see an example of a common chemistry method described using active and passive voice. Passive voice may seem more familiar, it is extremely common in methods sections of scientific articles. But why?

One reason is that methods are often written in the past tense, and people tend towards passive voice when writing past tense. Passive voice is useful when you need to be vague, or if the actor is unknown or irrelevant.

Another reason is personal liability. To say “The reagents were mixed but no products were obtained.” lies the blame on some unseen passive force; We know that the authors did the reaction, but in this sentence it’s not stated explicitly. In active voice, “We obtained no products”, adds some personal liability to the authors.

Lastly, academics often use passive voice because it seems more professional. This has been questioned for years and is finally starting to change.

Active voice is more clear and requires fewer words. In the example above you see that the active voice does not need an auxiliary verb or preposition. Since science is about generating ideas and taking ownership of actions, we should try to take responsibility for actions by using active voice. Passive sentences like “Studies have been conducted…” confuse the reader: Who did the studies, you or someone else? Should there be a citation?

Grammar and Spelling

While many like to argue, grammar is not set in stone, and there are specific rules for grammar in science. Still, using acceptable grammar is important when writing scholarship applications and journal articles; you don’t want to annoy your reviewers!

The newer versions of Microsoft Word (Office 365 Suite) provide grammar corrections along with classic spell check. There are also many resources online, including the free version of the Grammarly tool. This tool allows you to upload text and scans it for grammar, spelling, clarity, and wordiness. With Grammarly you can tune your feedback by setting your audience (general, knowledgeable, expert), formality, context (email, academic, business), and even tone.

Punctuation

(.) period – terminates a sentence; abbreviations
(?) question mark – terminates a question
(!) exclamation point – terminates an exclamatory statement
(,) comma – pauses the flow of a sentence to prevent ambiguity
(-) hyphen – clarifies compound modifiers
(–) dash – sets off phrase with emphasis; don’t overuse
(:) colon – initiates series
(;) semicolon – initiates independent clause
( ) parenthesis – encloses nonessential words and phrases

Commas: use after an introductory phrase “Therefore, we…”, to separate clauses (after and, but, or…), and to enclose phrases “The catalyst, which we make in our lab, works at low concentrations”.

Hyphens: Use for compound adjectives like “high-spatial-frequency components”. Do not use a hyphen as a negative sign symbol!

Capitalization: Capitalize titles of journals, books, reports ( Journal of the American Chemical Society), and references to figures (Chapter 2, Figure 8, Appendix C). Do not capitalize medical terms, laws, principles, theories,  or constants, unless they are eponyms.

• infectious mononucleosis; third law of thermodynamics; synthesis
• Alzheimer’s disease; Boyle’s law; Avagadro’s number

Unless at the beginning of a sentence or title, the name of an element (iron) is not capitalized but the short form (Fe) is always capitalized.

Italics: use for Latin words (et al., e.g., cis, trans) and for emphasis.

Bold: use for headings, compound numbers (compound 34 was…), and for emphasis.

Abbreviations:

• M.Sc.
• Ph.D.
• et al. (and others)
• i.e. (that is)
• e.g. (for example)
• Fig. (figure), Eq. (equation)
• Acronyms: NMR, ESI-MS, HTML

Table 2.1. Unit abbreviations

Numbers: You can either use Arabic numerals (1,2,3) or write out numbers as words (one, two, three). At the start of a sentence, write out the number. In other situations, do what is best for the flow of the paper. If two numbers appear together in a sentence (see example below), spell out one of them. Express units of measure and percents in Arabic numerals.

Common spelling mistakes

The molecule is a dimmer with a low molecular wait and tongues ten is the central element. 

A traditional spell checker finds no mistakes in the above sentence! The new proofing features in Microsoft Word (Office 365) are very good but are unfamiliar with terms used in scientific writing. One solution is to download and use a customizable Chemistry Spell-Check Dictionary for Word Processors.

It’s and Its

It’s is a contraction of the words “it is”. Its is a possessive form of it. People confuse these because apostrophes are often used in other possessive forms of words.

It’s always a good idea to dry your reagent and check its purity.

Your and You’re

You’re is a contraction of “you are” and your is a possessive form of you.

When you’re using the instrument you should have your goggles on!

Lose and Loose
Loose can be an adjective or verb and means the opposite of tight or contained. But lose is always a verb:

If the flask is loose and falls then I could lose my entire reaction mixture.

Compliment and Complement

Complement is used for something that matches or completes a set. A compliment is something nice you say to someone.

I want to compliment you on your style: your lab coat complements your goggles nicely.

Principal and Principle

In science you probably mean to say principle. A principal is the head of a school.

Queen’s has a principal instead of a president, who upholds our universities principles.

Except and Accept
Accept means to include, but except means to exclude.

I can’t accept that result, except if you are sure you ran the procedure properly.

Affect and Effect
Effect is a noun, something that happens. Affect is a verb.

Increasing the temperature in my reaction had a dramatic effect on the yield, this affected my plans for the next stage of the study.

Paragraph Structure

This section is adapted from Communication at Work by Jordan Smith which is licensed under a Creative Commons Attribution 4.0 International License.

Like sentences, paragraphs should vary in length depending on audience needs and abilities, as well as the topics being covered. An audience with advanced literacy skills can handle longer paragraphs that would lose an audience reading at a more basic level, which takes us back to our earlier points about adjusting the message to the audience profile. Some topics need more development sentences than others and don’t easily divide in the middle, though a paragraph of ten sentences or more is really pushing it. “Wall-of-text” paragraphs longer than a page are out of the question in professional writing. No matter what the size, however, all paragraphs should follow the standard structure explained below so that readers at any level can easily find what they’re looking for.

A well-organized paragraph has three parts :

1. Topic sentence
2. Body or development sentences
3. Transitional or concluding sentence

The topic sentence states the main point or thesis of the paragraph and thus summarizes the small collection of sentences following it, so the reader can take in the whole before examining the parts. In the following body sentences, readers should be able to see how every sentence in any well-organized paragraph expands on something said in the topic sentence. The sentences that follow the topic sentence (including this one) illustrate how that system works with examples. The final concluding sentence wraps up the topic as broached in the first sentence while bridging to the next topic sentence, which in this case is about how to come up with a topic sentence.

1. TOPIC SENTENCE

For many writers, drafting a topic sentence is typically a search for one while writing the rest of the paragraph first and then discovering it as a concluding summary exercise. When you are just putting ideas down in the drafting stage of the writing process, you may not know yet what your point is at the outset of writing a paragraph. You likely have a general sense of your topic and some points to cover, probably based on information you collected in your research earlier. As you connect that evidence and build sentences around those information points, you begin to see where you’re going with the topic and it suddenly comes into focus near the end. If you then say “In conclusion, …, ” summarize what you were getting at in a nutshell, and leave it there, however, you will do your reader a disservice by leaving your topic sentence buried under the pile of evidence that should be supporting it. In this case, delete “In conclusion,” highlight the final sentence, cut and paste it at the top of the paragraph so it does what a topic paragraph should do: preview what follows with an at-a-glance summary.

2. BODY OR DEVELOPMENT SENTENCES

The development sentences expand on every part of the topic sentence in a sequence of complete thoughts. The sentences that comprise this sequence explore the topic by following an organizing principle through detailed explanations, supporting evidence, illustrative examples, rhetorical counterpoints, and so on. As parts of a logical sequence of sentences, each sentence connects to those around it with pronouns that use effective repetition (referring to nearby points without repeating them word for word) and transitional expressions (see Table 2.2) to drive the topic exploration forward. In this paragraph, for instance, the pronoun “this” in the first development sentence (the second sentence in the paragraph) represents the topic (development sentences). In the sentence above this one, the transitional phrase “for instance” signals an illustrative example offered as supporting evidence of the topic sentence thesis on the sentences’ path towards the transitional or concluding sentence.

3. TRANSITIONAL OR CONCLUDING SENTENCE

The final sentence of a well-organized sentence wraps up the topic exploration by completing the main point stated in the topic sentence, as well as establishing a thematic bridge to the topic sentence of the next paragraph if indeed there is one. As a bridge, the final sentence looks forward to the following topic sentence by previewing some of its terminology, just as the paragraph preceding this one does. As a wrap-up, the final sentence should do more than merely paraphrase the topic sentence. Rather, the final sentence completes the expansion of topic-sentence points carried by the development sentences, leaving no loose ends to confuse the reader.

Paragraph Coherence

Coherence is achieved by paragraphs sticking to the topic summarized in the opening sentence, as well as using pronouns and transitional expressions to link sentences together while developing that topic. Generally, a paragraph sticks to just one topic while the one following it covers a related but distinct topic.

Like the organizational principles we explored above, we have a repertoire of recognizable pronouns, transitional expressions, and particular words or phrases that connect ideas in our writing so readers can easily follow our trains of thought. Pronouns such as ‘this’, ‘it’, ‘they’, ‘he’, ‘she’ allow us to represent nouns, phrases, and even whole sentences that came before (called antecedents) without repeating them word for word—as long as the antecedents are clear (Pronouns, 2016; Darling, 2014).

Transitional expressions drive a topic forward by establishing the relationships between the content of sentences. Table 2.2 below collects many such adverbs and conjunctive adverbs, prepositions and prepositional phrases, coordinating and subordinating conjunctions, infinitive phrases, interjections, and so on.

Table 2.2. Transitional expressions. Source: Transitional Expressions (2003) – use with caution!