Here's a breakdown:

* Hydrogen: Makes up about 70.6% of the Sun's mass.

* Helium: Makes up about 27.4% of the Sun's mass.

The remaining 2% is composed of trace amounts of heavier elements like oxygen, carbon, neon, and iron.

The Sun's energy comes from nuclear fusion happening in its core, where hydrogen atoms are fused together to form helium, releasing immense amounts of energy in the process.