the two most abundant elements in earth’s atmosphere today are
Abundance of the chemical elements The order of elements by volume-fraction (which is approximately molecular mole-fraction) in the atmosphere is nitrogen (78.1%), oxygen (20.9%),[14] argon (0.96%), followed by (in uncertain order) carbon and hydrogen because water vapor and carbon dioxide, which represent most of these two elements in the air, are variable components. Sulfur, phosphorus, and all other elements are present in significantly lower proportions.
Chemical element A chemical element is a species of atoms having the same number of protons in their atomic nuclei (that is, the same atomic number, or Z).[1] 118 elements are identified, of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radionuclides, which decay over time into other elements. Iron is the most abundant element (by mass) making up Earth, while oxygen is the most common element in the Earth's crust.[2]