Elements are the fundamental building blocks of everything in the vast universe. These atoms determine the properties and interactions of all matter. Understanding element prevalence helps scientists unravel the cosmic story of formation and evolution. This cosmic inventory reveals one element’s striking dominance, shaping the very fabric of the cosmos.
The Dominant Element
Hydrogen is the most common element throughout the universe. With atomic number 1, it has a single proton in its nucleus, making it the simplest and lightest chemical element. By mass, hydrogen accounts for approximately 75% of all normal matter.
Why It Is So Abundant
Hydrogen’s abundance traces back to Big Bang nucleosynthesis. Within minutes after the Big Bang, the universe was incredibly hot and dense, allowing for the formation of the simplest atomic nuclei. Protons and neutrons fused to create hydrogen and helium, along with trace amounts of lithium. As the simplest element, hydrogen was the most readily formed. While stars continuously convert hydrogen into heavier elements through nuclear fusion, the initial amount created during the Big Bang far outweighs this ongoing consumption.
Its Cosmic Presence and Role
Hydrogen is found everywhere in the cosmos, playing a fundamental role in astronomical phenomena. It serves as the primary fuel for stars, including our Sun, where intense heat and pressure cause hydrogen atoms to fuse into helium, releasing enormous energy. Vast clouds of hydrogen gas, known as nebulae, are the birthplaces of new stars and planetary systems. On planets, hydrogen is a component of water molecules and integral to organic compounds, forming the basis of life. Its fusion within stars is also the initial step in forging all other heavier elements, enabling chemical complexity in the universe.
Other Key Elements
While hydrogen dominates, other elements contribute to the universe’s composition. Helium is the second most abundant element, making up approximately 24% of normal matter, and also formed during Big Bang nucleosynthesis alongside hydrogen. Following these, common elements include oxygen, carbon, and iron. These heavier elements are not primordial; instead, they are forged later inside stars through nuclear fusion and dispersed into space during events like supernova explosions. This stellar recycling enriches the interstellar medium, providing raw materials for subsequent generations of stars and planets.