Mercury's atmosphere is incredibly thin and tenuous, often referred to as an exosphere. It's so thin that it's almost impossible to call it a true atmosphere.

While the major component of this exosphere is sodium, the "minor" gases are a bit more complex. They include:

* Hydrogen (H)

* Helium (He)

* Potassium (K)

* Oxygen (O)

* Calcium (Ca)

* Argon (Ar)

* Neon (Ne)

* Nitrogen (N)

* Xenon (Xe)

* Water vapor (H2O)

It's important to note:

* The abundance of these gases is extremely low, making them "minor" components.

* The exact composition can vary slightly depending on solar activity and other factors.

* The exosphere is constantly replenished by several sources:

* Solar wind: The sun's stream of charged particles brings some of these elements.

* Surface sputtering: Solar wind particles can knock atoms off the surface of Mercury.

* Outgassing: Some gases might be released from the planet's interior.

Mercury's exosphere is a fascinating subject, but it's still a mystery in many ways. Scientists are continuously learning more about its composition and dynamics.