What are the two most abundant chemical elements on Earth?
Oxygen is the most abundant element on Earth. It comprises 49.5 percent of the total mass (amount) of the Earth’s crust, waters, and atmosphere. Silicon is the second most abundant element. Silicon dioxide and silicates (salts derived from silicon dioxide) make up about 87 percent of the materials in the Earth’s crust. Source: Tzimopoulos, Nicholas D., et al. Modern Chemistry, pp. 289, 758.
