How Many Naturally Occurring Elements Exist?
The periodic table lists 118 confirmed elements — but not all of them occur naturally on Earth. Scientists generally recognize 94 naturally occurring elements, meaning they can be found in nature without being created in a laboratory or nuclear reactor.
The remaining 24 elements (atomic numbers 95–118) are synthetic: they are produced artificially through nuclear reactions and do not exist in measurable quantities in nature.
What Makes an Element "Naturally Occurring"?
An element is considered naturally occurring if it exists on Earth in detectable quantities through natural processes. These processes include:
- Primordial elements — formed before Earth existed, during stellar nucleosynthesis and the Big Bang (e.g., hydrogen, helium, carbon)
- Radiogenic elements — produced by the radioactive decay of other elements (e.g., radium is produced from uranium decay)
- Cosmogenic elements — formed continuously by cosmic ray bombardment of existing elements (e.g., carbon-14)
The 94 Natural Elements: A Quick Breakdown
Of the 94 naturally occurring elements, they span from hydrogen (atomic number 1) to plutonium (atomic number 94). Here's a summary of some key groupings:
| Category | Examples | Where Found |
|---|---|---|
| Abundant metals | Iron, aluminium, calcium | Earth's crust and core |
| Noble gases | Helium, neon, argon | Atmosphere |
| Rare earth metals | Cerium, neodymium, lanthanum | Mineral deposits |
| Radioactive elements | Uranium, thorium, radium | Rock formations |
The Most Abundant Elements on Earth
By mass, the most common elements in Earth's crust are:
- Oxygen — makes up about 46% of the crust by mass
- Silicon — roughly 28%
- Aluminium — about 8%
- Iron — about 5%
- Calcium, sodium, potassium, magnesium — each contributing smaller percentages
In the universe as a whole, hydrogen is by far the most abundant element, followed by helium.
What About Elements 93 and 94?
Neptunium (93) and plutonium (94) occupy an interesting middle ground. They were first produced synthetically, but scientists later confirmed they exist in trace amounts in uranium ores due to natural nuclear reactions. This is why they are included in the 94 naturally occurring elements, even though they are extremely rare in nature.
Key Takeaway
The number 94 is the widely accepted count of naturally occurring elements, though the boundary between "natural" and "synthetic" can be nuanced for elements near the top of that range. Understanding where elements come from — stellar explosions, radioactive decay, cosmic rays — is one of the most fascinating chapters in modern science.