Explanation

The human body contains traces of many elements, and approximately 99% of its mass is comprised of just six essential elements:

1. oxygen
2. carbon
3. hydrogen
4. nitrogen
5. calcium
6. phosphorus

Another five elements—

1. sulfur
2. potassium
3. sodium
4. chlorine
5. magnesium

Make up about 0.85% of the remaining mass, bringing the total of essential elements to 11