When to Capitalize Chemical Elements and Compounds in Writing

When it comes to chemical names in grammar, a common question is are chemical names capitalized? While chemistry can be confusing and contain many complex rules, the guidelines for capitalization are pretty straightforward.

Are chemical names capitalized?

In general, when dealing with chemical compounds and elements in grammar, there are a few things to remember. Chemical elements, like hydrogen, nitrogen, and helium, are not capitalized when used in a sentence. They should be treated the same as proper nouns.

Their chemical symbols, however, like H for hydrogen, N for nitrogen, and He for helium, are indeed capitalized.

This changes when chemical elements are used in a title. In a title, treat each chemical element like a common noun. In all writing styles, the first letter of each common noun is capitalized in a title. Take, for example, this title: “Properties of Hydrogen.” In the title, hydrogen should be capitalized.

What about chemical compounds?

The rules apply for chemical compounds, which are two or more chemical elements combined. For example, the chemical elements that makeup water are two molecules of water and one molecule of oxygen. The chemical compound is written out as dihydrogen monoxide.

In a sentence, dihydrogen monoxide would typically be written in its chemical symbols of H2O, but if it were to be written out in its elements, it would be lowercased dihydrogen monoxide. In a title, however, the words would follow the same rules as common nouns and be capitalized.

While this might seem complicated, it’s actually straightforward. Just remember, chemical elements and chemical compounds when used in a sentence should not be capitalized. When using the chemical symbols, which are the single or pairs of letters that replace the elements, the first letter should always be capitalized.

Finally, when using chemical elements and compounds in a title, the first letters should be capitalized.

To learn more about proper title capitalization rules, give our free title capitalization tool a try.

Capitalize My Title is a dynamic title capitalization tool used to make sure your titles or headlines use proper capitalization rules according to various style guides include APA, AP, MLA, and Chicago. It also counts your words and checks for grammar issues.


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