The Element Hydrogen
Introduction to Hydrogen
When it comes to the periodic table, the element hydrogen is number one – literally. It is both the lightest and simplest element, with only one proton, one electron, and an atomic number of one.
Ten Interesting & Fun Facts About Hydrogen
- Hydrogen makes up about 70% of the universe by mass, which makes it by far the most abundant element.
- In stars like the sun, hydrogen atoms collide to create Helium atoms, which is a fusion reaction.
- Though there are only three naturally occurring isotopes of Hydrogen, some with more neutrons can be made by bombarding Tritium (hydrogen with 2 neutrons) with Deuterium (Hydrogen with 1 neutron). These isotopes are highly unstable and have half-lives of fractions of a second.
- Tritium is a component of some high-end wristwatches and provides them with glowing hands. However, these watches stop glowing after about 12 years due to Tritium’s short half-life.
- Like Chlorine, Fluorine, Bromine, Iodine, Oxygen, and Nitrogen, hydrogen is diatomic. This means it occurs in nature most commonly as a two-atom molecule.
- Carbon and Hydrogen create hydrocarbons, which are a diverse family of organic compounds.
- When heated, Hydrogen gas reacts violently with Oxygen in the air to form water vapor.
- Because Hydrogen is lighter than air, it was used to float airships until accidents such as the Hindenburg disaster made people aware of its dangers.
- Hydrogen is a part of more different compounds than any other element except Carbon.
- The element Hydrogen is so light that it can escape Earth’s atmosphere when not contained.
Hydrogen in the Periodic Table
Hydrogen’s symbol is H, and its atomic number is 1. In its most common isotope, it has only one proton, one electron, and no neutrons. Though it sits in group one with the alkali metals, it is not metallic. It is also in period one with Helium.
Hydrogen has an electronegativity of 2.2 and is above lithium on the periodic table. Its electron configuration is 1s1. There are three naturally occurring isotopes of Hydrogen: Protium, Deuterium, and Tritium. Protium has no neutrons, Deuterium has one, and Tritium has two. Protium makes up 99.98% of the naturally occurring Hydrogen on Earth.
Hydrogen – The Haber Process
The Haber process is a common method of producing ammonia (NH3) for fertilizer. To do so, Hydrogen gas reacts with Nitrogen gas under high temperature and pressure with the help of a metal catalyst. This results in the creation of ammonia, which is then cooled. The process was created by and named after German scientist Fritz Haber, who won the Nobel Prize in Chemistry for this work.
A Hydrogen atom without its electron is just a proton. Having higher concentrations of protons in a solution makes the solution more acidic. This happens when Hydrogen dissociates from its bond to a more electronegative atom such as Chlorine. Hydrogen creates a variety of acids through bonding with the halogens or as a part of the carboxylic acid functional group.
On the other hand, when Hydrogen takes on an extra electron, it becomes a Hydride anion. This allows it to act as a base by picking up protons from the solution.
One of Hydrogen’s unique properties is Hydrogen Bonding. When Hydrogen is attached to Nitrogen, Oxygen, or Fluorine, it receives a slight positive charge. This allows Hydrogen to have intermolecular interactions with electronegative atoms that have a slight negative charge (like, once again, N, O, or F), causing them to stick together. In order for an electronegative atom to participate in Hydrogen Bonding, it must have a lone pair. Despite its name, Hydrogen Bonds are actually intermolecular forces rather than covalent or ionic bonds.
Hydrogen Bonding is the cause of water’s surprisingly high boiling point. Hydrogen and Oxygen atoms in different water molecules will attract each other, and this attraction must be overcome before water can boil. Because Oxygen is so electronegative, it creates strong Hydrogen Bonds.
Applications of Hydrogen in Today’s World
Hydrogen’s most common novel application today is as a potential alternative fuel. Unlike airships, which used large cavities full of Hydrogen to float, model Hydrogen fuel cells create power similarly to the way a battery does.
Hydrogen Fuel Cells
One of the most important uses of Hydrogen today is as an alternative to fossil fuels. Hydrogen fuel cells work by first separating the Hydrogen gas into protons and electrons. While the protons can easily pass through the membrane, the electrons cannot and therefore must take another way, producing an electrical current in the process. The Hydrogen protons and electrons then combine with Oxygen, forming water—the only by-product of this process. This means that Hydrogen fuel cells do not release any greenhouse gases. Additionally, Hydrogen fuel cells have the potential to be more efficient than internal combustion engines.
Currently, there is a limited number of Hydrogen fueling stations around the United States, and the production of Hydrogen Fuel cells is expensive as well. This means that if they do become common, it will not be until those problems are resolved.
One of the issues with using Hydrogen as a fuel source is that even though burning Hydrogen does not produce greenhouse gases, the main method of producing it does. To make Hydrogen gas, methane from fossil fuels undergoes a process called “steam reforming,” which turns the methane into Carbon Monoxide, which then becomes Carbon Dioxide.
Low-temperature Hydrogen (about -240°C) could also replace Kerosene as fuel for airplanes. Similar to Hydrogen Fuel cells, this method has the potential to produce less greenhouse gas emissions than Kerosene and reduce the amount of maintenance a plane requires.
Within the pharmaceutical industry, Hydrogen has uses in both the pathways to creating necessary starting materials and as a treatment. For example, Hydrogen is a major part of the production of Hydrogen Peroxide (H2O2). Hydrogen Peroxide has many uses in the chemical industry, both as an anti-microbial substance and an oxidizer.
In addition, because pharmaceuticals are organic compounds, Hydrogen is definitionally a part of them all. In organic compounds, Hydrogen acts as a placeholder. It takes up space to help Carbon make four bonds, but chemists often treat it as a part of the molecule not worth mentioning. Most of the time, the presence of Hydrogen simply indicates the lack of a functional group.
When and How was Hydrogen Discovered?
Though earlier scientists noticed Hydrogen’s traces, in 1766 English chemist Henry Cavendish became the first to demonstrate its existence as a unique element. Cavendish saw that when Hydrogen burned, it formed water.
Years later, in 1783, Antoine Lavoisier gave the element Hydrogen its name. The name “Hydrogen” comes from the Greek “Hydro” and “Genes,” which means water-forming.
American chemist Harold Urey discovered Deuterium, also called Heavy Hydrogen, in 1931. To make this discovery, Urey distilled the two isotopes from each other. In 1934, Urey won a Nobel Prize for his Hydrogen research.
Hydrogen Chemistry – Compounds, Reactions, Oxidation States, Isolation
Chemical Properties of Hydrogen
When burned, Hydrogen reacts violently with air to produce water (2 H2 (g) + O2 (g) → 2 H2O (g)). It exists in nature as a diatomic molecule or as a part of other chemical compounds.
Hydrogen makes such a wide variety of compounds that to list them all is impossible. However, many of the compounds Hydrogen is a part of fit into several broad categories.
Carbon and Hydrogen together make up organic compounds. Compounds that contain only these two types of atoms are called hydrocarbons. These compounds are flammable liquids and gases whose primary purposes are as fuels.
Hydrogen is also present in Amino Acids, which are the building blocks of life.
Even though Hydrogen is present in every organic compound, it usually does not play as important a role in defining the compounds’ properties as functional groups.
When part of an acid, the proton from the Hydrogen dissociates in the solution, which makes the solution acidic. The electron which belonged to the Hydrogen remains with the conjugate base.
NaH is an ionic compound made up of Na+ and H– ions. Unlike acids, which release a proton in solution, NaH releases a Hydride ion, which is basic. A Hydride ion is a Hydrogen atom with an extra electron that gives it a negative charge.
Without water, life on this planet would not exist as it does. Water is necessary for all living organisms. Because of Hydrogen Bonding, water has a high boiling point, which allows it to absorb more heat energy and not boil.
Industrially, one of Hydrogen’s most important applications is in the creation of NH3 for fertilizer.
Isolation of Hydrogen
Because Hydrogen gas is not easy to obtain directly from nature, it must be isolated from other compounds. It is separated from methane through steam reforming. This process also creates Carbon Dioxide as a byproduct. Another method of making Hydrogen is electrolysis, where an electric current splits apart water molecules to remove the Hydrogen.
Hydrogen Oxidation States
Hydrogen only has two oxidation states, +1 and -1. In ionic compounds, Hydrogen’s oxidation state depends on the relative electronegativity of the other ion. For example, when bonded to a halogen, Hydrogen is in its +1 state. This is also its more common oxidation state, as H takes on a +1 oxidation state when bonded to nonmetals. When bonded to a metal, it is in its -1 state.
Physical Properties of Hydrogen
Hydrogen is a colorless and odorless gas. It is the smallest and least dense element on the periodic table.
- Symbol: H
- Melting Point: -259.16 °C
- Boiling Point: -252.87 °C
- Density (g/mL): 8.988 x 10-5
- Atomic Mass: 1.008
- Atomic Number: 1
- Electronegativity (Pauling Scale): 2.20
- Classification: Group I, nonmetal
- Crustal Abundance: 0.14%
- Electron Configuration: 1s1
- Isotopes: Protium, Deuterium, Tritium
- Found naturally in: water, ammonia, organic compounds
- Toxicity: Hydrogen is not toxic
Where can I buy Hydrogen?
Companies such as Cal Gas Direct sell Hydrogen gas in metal canisters. The gas generally costs between $1-3 per liter.