The most abundant element in the entire universe is hydrogen, making up about 3/4 of all matter. Helium makes up most of the remaining 25%. Oxygen is considered the third most abundant element in the universe. All other elements are relatively rare.
The chemical composition of our Mother Earth is quite a bit different from that of the universe. The most abundant element in the earth’s crust is oxygen, making up 46.6% of the mass. Silicon is the second most abundant element (with 27.7%), followed by aluminum (8.1%), iron (5.0%), calcium (3.6%), sodium (2.8%), potassium (2.6%). and magnesium (2.1%).
The most abundant element in our human body is oxygen, which makes up about 65% of the weight of each person.