This chapter provides a basic understanding in the form of a fact sheet for the element hydrogen—the oldest and cleanest element in the world—including its characteristics and physical properties, uses, sources, and other data. Hydrogen is the lightest and most abundant element in the universe; approximately 75% of the mass of the Sun, but only a tiny fraction of the Earth, is comprised of hydrogen. A hydrogen atom consists of one proton and one electron and it is the first element on the periodic table. One of the most serious gases we use is hydrogen—in our cars, buses, space launches from the Cape, and so on.
- 3.US Department of Energy. https://www.eere.energy.gov/hydrogenandfuelcells