Sciency Words PHYS copy

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Every Friday, we take a look at a new and interesting scientific term to help us all expand our scientific vocabularies together. Today’s word is:


In colloquial English, the word volatile is an adjective used to describe things like the stock market or the Middle East. But as a technical, scientific term, volatile is a noun.

Volatiles are chemicals that tend to turn into gas at relatively low temperatures or when exposed to a vacuum (like the vacuum of space). Examples include:

  • Hydrogen
  • Oxygen
  • Ammonia
  • Methane
  • Water

Many volatiles are so eager to become gases that they’ll sublimate, meaning they’ll transform from solid to gas without bothering to be liquids first.

As we continue our exploration of the Solar System, we’ll be talking about this class of chemicals a lot. They’re especially important if you want to understand why Mercury is the way that it is. More about that on Monday.


Volatiles from Wikipedia

Outgassing from Wikipedia

10 responses »

  1. This really takes away the force of the colloquial usage for me. The next time someone describes something as volatile, I’ll think “eager to evaporate” instead of “ready to explode.” I wonder how we came to use the term the way we do if that’s the technical meaning. Any clues in the history?


    • James Pailly says:

      I’ve had the same problem. Just the other day, someone made a comment about another person’s “volatile personality” which I, for a moment, understood as a personality that will readily evaporate.

      The history of this word will mess with your brain even more. According to the O.E.D., the word originally meant “creatures that fly,” or in other words, “birds.” I now think of that whenever I see a flock of geese.

      The meanings “explosive” and “evaporative” somehow evolved from that “bird” meaning at approximately the same time (circa 17th Century), and the original meaning was lost.

      Liked by 1 person

  2. […] little air Mercury has comes from several sources. Volatile chemicals seep out of the planet’s crust through a process called outgassing. In addition, those […]


  3. […] The Moon has a lot in common with the planet Mercury, and just like Mercury, the Moon has trouble retaining its volatiles. […]


  4. […] The Moon has a lot in common with the planet Mercury, and just like Mercury, the Moon has trouble retaining its volatiles. […]


  5. […] closest approach to the Sun, making it warmer than northern summer. This extra heat releases extra volatiles (mostly CO2 gas) from the south polar ice cap. This agitates the atmosphere, which in turn whips up […]


  6. […] Volatiles like water vapor are constantly spewing from certain Saturnian moons. Perhaps these outgassed […]


  7. […] and Neptune accumulated vast quantities of ice (hence the name ice giant). By ice, I mean any volatile substance in a solid state, not just water […]


  8. […] (which makes the most sense to me) is that is was a comet. Comets are composed of lighter, more volatile chemicals like water. So when the Tunguska comet exploded, it would have been completely vaporized, […]


  9. […] Heat radiating from the baby star plus heat trapped in the disk itself vaporizes water and other volatile chemicals, which are then swept off into space by the solar […]


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