* Hydrogen (H): About 70.6% of the Sun's mass

* Helium (He): About 27.4% of the Sun's mass

The remaining 2% is made up of heavier elements, including:

* Oxygen (O): 0.8%

* Carbon (C): 0.3%

* Neon (Ne): 0.2%

* Iron (Fe): 0.1%

* Silicon (Si): 0.1%

* Magnesium (Mg): 0.07%

* Sulfur (S): 0.04%

* Nickel (Ni): 0.03%

* Calcium (Ca): 0.02%

* Chromium (Cr): 0.02%

* Sodium (Na): 0.01%

* Aluminum (Al): 0.01%

The Sun's composition is a result of the nuclear fusion reactions occurring in its core, where hydrogen atoms fuse to form helium, releasing a tremendous amount of energy. This process has been ongoing for billions of years, and the Sun's composition is constantly evolving as more hydrogen is converted into helium.

It's important to note that even though the Sun is mostly hydrogen and helium, the heavier elements play crucial roles in the Sun's structure and evolution.