The elements of the periodic table are arranged in columns or groups. This way, carbon belongs to group IV, whereas nitrogen is in group V.
If these group names are used as adjectives, should they be hyphenated or is hyphenation optional? For example, which should I use:
Different group-IV materials can be used in microelectronics.
Different group IV materials can be used in microelectronics.
I have seen both ways in different scientific papers.
When two words together serve as a modifier for another word, many style manuals recommend hyphenating them, as for example…
The built-up area of town…
A brightly-lit hallway…
Since this is related to chemistry, I checked the American Chemical Society’s style manual, which does not specifically address phrasal adjectives, but does favor hyphenation for most modifiers.
However, if you’re writing for a specific journal or publication, you may want to ask them what style guide they recommend.