What Characteristics Does Hydrogen Have?
- Nearly 75 percent of the universe's visible mass is comprised of hydrogen, making it the most abundant of all 118 known elements. Hydrogen holds the number-one position of elements on the periodic table due to its single, positively charged proton and one negatively charged electron, according to the University of Nottingham's Periodic Table of Videos website. This single proton also designates hydrogen as the simplest element in the universe.
- Hydrogen is classified as a non-metal, has an atomic weight of 1.00794 grams per mole; a density of 0.0000899 grams per cubic centimeter and an atomic volume of 14.4 cubic centimeters per mole. Hydrogen has a melting point of 14.01 K, a boiling point of 20.28 K, a triple point of 13.8033 K and a critical point of 32.97 K. Hydrogen occurs in three isotopes. Each isotope contains one proton and one electron, but hydrogen can also have one or two neutrons. Hydrogen with one extra neutron is deuterium, while tritium has two additional neutrons. Nuclear fusion reactors use both deuterium and tritium as fuels; deuterium and tritium have been used in thermocuclear weapons.
- Because odorless, tasteless, colorless hydrogen gas is the lightest of the gases, only trace amounts exist in Earth's atmosphere -- any pure hydrogen gas rises quickly into space. Hydrogen is present in all living matter in the form of compounds, the most famous of which being two atoms of hydrogen bonded with one atom of oxygen, or water. According to the U.S. Energy Information Administration's Energy Kids website, hydrogen combines with carbon to form various energy-producing compounds, hydrocarbons, such as petroleum, methane and coal.
- According to the Universal Industrial Gases website, the most common means of producing hydrogen is through a steam reforming process of methane gas or other hydrocarbons. Simply put, this method separates hydrogen atoms from carbon atoms in the compounds. Hydrogen is also separated from water through electrolysis, an emission-free procedure that splits hydrogen atoms from oxygen atoms of water molecules. For ease of storage and safety in handling, hydrogen is often converted to a liquid state from a gas by significantly reducing its temperature. Hydrogen gas becomes a liquid when brought below its boiling point of -423 degrees Fahrenheit.
- When mixed with oxygen, hydrogen gas is highly flammable. Even though hydrogen gas has no toxicity, in small, enclosed spaces, hydrogen gas leaks pose asphyxiation dangers, because the extremely light gas diffuses quickly and fills an area.