Can we, and should we, ever really be neutral? In a new series, Zócalo explores the idea of neutrality—in politics, sports, gender, journalism, international law, and more. In this essay, chemist Paul G. Jasien considers what “neutral” means in the lab and beyond.

The meanings of certain words can be less clear-cut than one might expect when they appear in different contexts. In Lewis Carroll’s classic book Through the Looking-Glass, for instance, the following conversation takes place between Alice and Humpty Dumpty:

“When I use a word,” Humpty Dumpty said in a rather scornful tone, “it means just what I choose it to mean—neither more nor less.”

“The question is,” said Alice, “whether you can make words mean so many different things.”

Words that mean one thing in everyday speech may have very specific and possibly quite different meanings in other contexts, particularly in science. There are many such words, but one example of this ambiguity is the meaning of the word neutral. In chemistry, neutral defines a specific state of matter—a water solution that is neither acidic nor basic, or an atom or molecule with no electrical charge. But in non-scientific uses of the word, it generally means “not favoring either side,” such as in a contest or competition.

In non-scientific contexts, it is usually clear what it means to not take a side: We can think of a “neutral judge” or a “neutral playing field.” But when using neutral in a scientific context, such as a “neutral solution” or a “neutral atom,” the “sides” in the contest may not be as apparent, although the basic definition still can be made to fit. Alternate meanings for the same term can be confusing when trying to describe a scientific concept in the classroom. This issue arises with many terms commonly used in biology, chemistry, and physics.

Let’s more closely examine the word neutral as used in the phrase “neutral water solution.” Chemically, all water solutions contain two charged components: the hydrogen ion and the hydroxide ion. (An ion is simply an atom, molecule, or sometimes larger aggregate that has an electrical charge.) An acidic solution is one in which the concentration of hydrogen ions is larger than that of hydroxide ions, whereas a basic solution is one in which the opposite is true. A “neutral solution” describes a very special state of the water solution in which the concentration of hydrogen ions is exactly equal to that of hydroxide ions. Applying the colloquial meaning of neutral—“not favoring either side”—in trying to understand the scientific concept can often lead to confusion. For instance, in my experience, chemistry students often incorrectly associate neutral in the phrase “neutral solution” with stationary or unchanging, and subsequently with a solution that is chemically unreactive.

Alternately, when scientists use the term neutral to describe an electrical state of a sample of matter, the two “sides” in the competition are the positively-charged subcomponents of atoms known as protons and the negatively-charged subcomponents known as electrons. In this case, understanding the concept of neutral through the lens of “not favoring either side” would be with respect to having equal numbers of protons and electrons—and thus, no excess positive or negative electrical charge. Applying the general definition here works to a point, but can also lead to inconsistencies such as equating neutral with inactive or stable.

Understanding of the meaning of neutral can get more confusing when the related term neutralize is considered. In everyday speech, to neutralize someone or something is often taken to mean “to remove the threat of someone or something that might be dangerous, especially by killing them or destroying it.” One might casually speak of “neutralizing a poison” or “neutralizing an enemy threat.” Although the former use sounds scientifically accurate, to neutralize in chemistry means something very narrow: to react a hydrogen ion with a hydroxide ion to form a water molecule. When that occurs, a solution can become either less acidic or less basic but there is no killing—these are inanimate chemical species—nor destroying, because of the fundamental principle of conservation of matter in chemical processes. In an acid-base reaction, the component parts are still present, but in a different combined form.

Although a good chemist would not equate “neutralizing a poison” with an actual acid-base neutralization reaction, a novice chemistry learner might—making the actual meaning of “neutralization” murkier in his or her mind. This is yet another instance in which the overlapping contextual meanings of a word like neutral, or its variants, have the potential to lead a person to misunderstand the meaning of a scientific term.

Many years of observing university-level students’ understanding (and misunderstanding) of multiple-meaning terms have convinced me that science learners need to develop skills in discerning and contextualizing word meaning—not only to advance their basic science skills, but to better prepare themselves for their professional lives. But the responsibility of overcoming the tendency to conflate scientific and colloquial meaning should be shared by instructors and students alike.

Science vocabulary is often taught through rote memorization, but this is not the only means to do so. As the science educator Arnold B. Arons observed, scientific terms “are metaphors, drawn from everyday speech, to which we give profoundly altered scientific meaning, only vaguely connected to the meaning in everyday speech.” Therefore, “students remain unaware of the alteration unless it is pointed to explicitly many times.”

If we want chemistry students to really understand acids, bases, neutral solutions, what it means to be electrically neutral, and other scientific concepts, we must emphasize the places where scientific language differs from everyday speech.

Learning concepts in a specialized subject often entails learning to use a new language built of familiar words. A part of this requires being able to reconcile a previous understanding of what certain terms mean in the language of that subject. In other words, it is necessary to be able to compartmentalize language for various subjects or audiences. Science educators need to carefully consider how understanding of the subtle differences between colloquial and scientific usages of specific terms may be essential in forming a deep understanding of scientific concepts.

An analogous, but not quite equivalent situation in confusing word meaning arises in learning a foreign language where English sounding words mean something totally different in another language despite shared Latin roots. For example, Spanish’s embarazada does not mean embarrassed, but pregnant.

Learning technical concepts can be difficult, especially when it involves cognitive conflicts that necessitate replacing what you believed with a more correct interpretation. Words, including neutral, are the major currency of human communication both in science, and in social discourse. It is imperative that we negotiate and contextualize word meaning so we can better understand the world around us and communicate with each other.