What are the 7 most common elements?

The 7 Most Common Elements on Earth

When we look around—at the ground beneath our feet, the air we breathe, or the structures built by humans—we’re actually seeing the work of just a few key chemical elements. While the periodic table boasts over a hundred entries, only a handful dominate the composition of our planet.

Oxygen tops the list, making up nearly half of Earth’s crust by mass. It’s not just in the air we breathe—oxygen bonds with other elements to form minerals in rocks and soil. Right behind it is silicon, the backbone of silicate minerals that form the bulk of Earth’s mantle and crust. Together, oxygen and silicon create the sturdy foundation of our solid planet.

Aluminum and iron are next in line—both metals vital to both nature and industry. Aluminum is lightweight and abundant in clay and feldspar, while iron, though more concentrated in Earth’s core, is still a major component of the crust and essential to everything from hemoglobin to heavy machinery.

Calcium, sodium, and magnesium round out the list. Calcium builds rocks like limestone and gives strength to bones and shells. Sodium, best known as table salt, plays a crucial role in ocean chemistry. Magnesium, often overlooked, is central to chlorophyll and thus to plant life.

Though not always in the top seven by crustal abundance, hydrogen deserves mention—it’s the most abundant element in the universe and key to water and organic chemistry. Together, these elements shape the physical world and sustain life as we know it. From the air to the rocks to our own bodies, these common elements are quietly running the show.