What is the primary element that makes up 90% of normal matter?

Hydrogen is the primary element that makes up 90% of normal matter, which reflects its fundamental role in the universe. As the simplest and most abundant element, hydrogen comprises one proton and one electron, making it the building block for more complex elements. In the early universe, hydrogen was primarily formed during the Big Bang nucleosynthesis and has remained prevalent ever since.

In stars, hydrogen undergoes nuclear fusion, converting it into heavier elements, but the sheer quantity of hydrogen present in the universe ensures that it remains the dominant element. This process also drives the lifecycle of stars, leading to the formation of galaxies, and ultimately influencing the composition of the universe at large. Thus, recognizing hydrogen as the most abundant element helps to understand not only the nature of normal matter but also various astrophysical processes.