What is the sum of the atomic numbers of these three chemical elements: hydrogen, carbon, and oxygen?

The identity of every chemical element is fundamentally defined by its atomic number, which represents the precise count of protons found within the nucleus of an atom of that element. For hydrogen, the simplest and most abundant element in the universe, this number is 1. Carbon, the foundational element for all known life, possesses an atomic number of 6. Oxygen, vital for respiration and a major component of Earth's atmosphere and water, has an atomic number of 8. Adding these values together, 1 + 6 + 8, reveals a total of 15.

These three elements, hydrogen, carbon, and oxygen, are not just arbitrary choices; they are fundamental to existence as we know it. Hydrogen and oxygen famously combine to form water, H2O, essential for all life on Earth. Carbon, with its unique ability to form four stable bonds, acts as the backbone for countless organic molecules, from simple sugars and fats to complex proteins and the very DNA that carries genetic information. Together, they constitute the vast majority of the mass of living organisms and are critical components of Earth's atmosphere, oceans, and geology.

Understanding atomic numbers is key to comprehending the periodic table and how elements interact. Each element's unique atomic number determines its position on the periodic table, which in turn dictates its chemical properties and how it will bond with other elements. This fundamental concept allows us to predict and explain the vast diversity of chemical compounds that make up our world, from the air we breathe to the cells in our bodies.