The universe is composed of 92 naturally occurring elements, yet a few dominate the cosmos. The overwhelming majority of the universe's ordinary matter is made up of just two elements: Hydrogen and Helium.
Hydrogen (H)
Hydrogen is the lightest and most abundant element in the universe, making up approximately 75% of its elemental mass. It is primarily found in the plasma of stars, where it undergoes nuclear fusion to create energy and heavier elements.
|
Atomic Number |
Abundance (by Mass) |
Primary Location |
|---|---|---|
|
1 |
~75% |
Stars, interstellar gas clouds |
Helium (He)
Helium is the second most abundant element, accounting for nearly 25% of the universe's elemental mass. Like hydrogen, it is a light gas and is mostly found in stars, where it is a product of hydrogen fusion.
|
Atomic Number |
Abundance (by Mass) |
Primary Location |
|---|---|---|
|
2 |
~24% |
Stars, planetary atmospheres |
Oxygen (O)
After the two lightest elements, oxygen is the most common element, though it makes up a much smaller percentage of the total mass. Oxygen is a crucial component of water, minerals, and the atmosphere of rocky planets. It is formed in the cores of massive stars.
|
Atomic Number |
Abundance (by Mass) |
Primary Location |
|---|---|---|
|
8 |
~1.0% |
Planets, molecular clouds |
Carbon (C)
Carbon is the fourth most common element by mass. It is the fundamental building block of all known life and is essential for organic chemistry. Like oxygen, carbon is created inside stars through nuclear fusion.
|
Atomic Number |
Abundance (by Mass) |
Primary Location |
|---|---|---|
|
6 |
~0.5% |
Organic molecules, stars, planets |
Other Common Elements
While Hydrogen, Helium, Oxygen, and Carbon are the most abundant, the following elements are also found in significant quantities throughout the universe, often as products of stellar evolution and supernovae:
- Neon (Ne): An inert gas produced during the late stages of stellar fusion.
- Iron (Fe): The heaviest element created by fusion in ordinary stars and the final stable element in a star's core before collapse.
- Nitrogen (N): A key component of Earth's atmosphere and an essential element in amino acids.
- Silicon (Si): A main component of most rocky planets and their crusts.