Everything Everywhere Daily: History, Science, Geography & More - Nitrogen

Starting point is 00:00:00 If aliens were to look at the Earth through a telescope from far away and analyze our atmosphere, they would find that the dominant element is nitrogen. Nitrogen makes up 78% of our atmosphere, and it's all around us. However, it behaves very differently than other common elements. Nitrogen isn't just vital for the functioning of life, but it's also used in various industrial and chemical applications as well. Learn more about nitrogen, the invisible yet vital element on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed.

Starting point is 00:00:52 It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR. I've previously done episodes on the elements carbon and oxygen, which sit immediately on either side of nitrogen on the periodic table. table. Nitrogen, despite being neighbors with these elements, behaves very differently. Oxygen is very reactive, with six electrons in its outer shell. Carbon has four free electrons, which allows it to bond in a wide variety of ways with different elements. Nitrogen has five electrons. As with carbon and oxygen, understanding nitrogen involves understanding its atomic structure.

Starting point is 00:01:36 Nitrogen is the seventh element on the periodic table and the seventh most abundant element in the universe. With seven protons in its nucleus, it also has seven electrons. Two fill up its inner shell and five are in its outer shell, which can hold up to eight. That means that nitrogen has three electron spots in its outer shell that it wants to fill. This is really the fundamental thing you need to know about nitrogen. While I suppose you can say this is true with every element, in the case of nitrogen, it really likes to bond with other nitrogen atoms to form a nitrogen molecule known as N2. When nitrogen bonds with itself, it creates a very strong triple covalent bond.

Starting point is 00:02:15 More on this extremely important bit in a moment. While humans have been breathing nitrogen ever since they first existed, and why several nitrogen compounds have been known since antiquity, nitrogen as a separate element, was unknown up until a few centuries ago. The discovery of nitrogen is usually attributed to the Scottish chemist Daniel Rutherford, who identified a component in air that didn't support combustion in 1772. Rutherford's initial name for this gas was noxious air. Rutherford didn't know that his noxious gas was in fact a separate element.

Starting point is 00:02:48 The French chemist Antoine Lavassier did experiments as well and found out that any living thing subject to an atmosphere consisting of only this gas died. He called it mephitic air. The English word comes from the French word, Nitrogen, which is a combination of nitre, which comes from the French word for Salpeter, and Jen from the Greek word for creation, as in Genesis. As I noted in the introduction, nitrogen is the overwhelmingly dominant gas

Starting point is 00:03:15 that makes up our atmosphere. 78% of the air you breathe is made up of nitrogen in molecular form. However, because the atoms in a nitrogen molecule are bound so tightly with each other, for the most part, nitrogen acts like an inert gas. It doesn't react with much because it's so hard to break apart the bonds

Starting point is 00:03:34 within a nitrogen molecule. The inertness of nitrogen molecules does have its uses. Nitrogen is one of the most commonly used gases used for preserving items. You pump in nitrogen to displace oxygen, and whatever it is you're trying to preserve will last longer without any oxygen to react with. This is most commonly done with food. Many incandescent light bulbs are filled with nitrogen, so the filaments inside don't quickly combust in the presence of oxygen. Nitrogen is cheap and abundant, so it's preferable in most applications to truly inert gases, such as argon or helium. However, as I also mentioned in the introduction,

Starting point is 00:04:08 nitrogen is vital for life. Every amino acid, and hence every protein molecule, has to contain nitrogen. If so much of nitrogen is tightly bound up with itself in the form of nitrogen molecules in the air, how do life forms get access to nitrogen? This is done through a process known as nitrogen fixation. Nitrogen fixation is a crucial biological process that converts atmospheric nitrogen gas into ammonia or other nitrogen compounds that plants and other organisms can use. Plants and animals cannot process atmospheric nitrogen molecules directly. They require it to be done by other means. One way in which nitrogen is fixated, although it doesn't account for much nitrogen fixation, is via lightning. Lightning strikes carry enormous amounts of energy that can

Starting point is 00:04:58 break apart the nitrogen bonds and allow nitrogen to bond with oxygen to form nitrogen oxides. However, the vast majority of nitrogen fixation on Earth is done via single-celled organism such as bacteria and archaea. These microbes are known as deazotrophic, and they're able to convert molecular nitrogen into usable forms via a class of enzymes known as nitrogenases. There are two types of deazotrophic microbes. The first are those that live free in the soil. They are not symbiotically attached to any plants, but the nitrogen that they fixate is usable

Starting point is 00:05:31 by any plants that happen to be nearby. The other type are those that have symbiotic relationships with plants. Bacteria such as rhizobium and Brady rhizobium form symbiotic relations with specific plants, often legumes such as soybeans, peas, and clover. In these mutualistic relationships, the bacteria reside inside specialized root nodules of the host plant. The plant provides a bacteria with sugars and other nutrients, while the bacteria converts atmospheric nitrogen into ammonia and provides it to the plant as a nitrogen source. In return, the plant benefits from increased nitrogen availability, which enhances its growth.

Starting point is 00:06:09 Once the plants consume the nitrogen, animals then eat the plants and the free nitrogen is placed into the food chain. Nitrogen is extremely important for plant growth, and something that farmers have to take into consideration. If too many crops are planted in succession without nitrogen fixing bacteria, the soil will eventually become exhausted of nitrogen. This is one of the reasons why farmers practice crop rotation. Between crops such as corn or wheat, other nitrogen fixing crops such as legumes add nitrogen to the soil. Sometimes these crops aren't even harvested. They're just plowed back into the ground to provide even more nutrients. Crop rotation was not the only way that farmers would add nitrogen to the soil. They would also fertilize the soil, usually through the addition of manure from farm animals or other by products like Ophal or blood. Native Americans famously taught the early English settlers how to grow corn by planting each stalk on the remains of a fish.

Starting point is 00:07:01 which provided nitrogen for the plant. However, as crop production grew in the 19th century, natural fertilizer was reaching its limits. There's only so much manure to go around. Guano, aka bird poop, deposits were mined around the world, but they were a very limited resource. By the start of the 20th century, there were concerns about the inability

Starting point is 00:07:21 to provide enough nitrogen fertilizer to feed the world's growing population. The man who solved this problem was the German chemist Fritz Haber, on whom I've done a previous episode. Hobber developed a system for artificially taking atmospheric nitrogen and creating ammonia. In 1909, he was able to perform a laboratory demonstration that could produce drops of ammonia at the rate of about 125 milliliters or four fluid ounces an hour. Haber sold his invention to the German chemical company BASF, who in turn gave Carl Bosch the assignment of scaling up the process so ammonia could be produced at an industrial scale.

Starting point is 00:07:57 Now known as the Haber-Bosch process, it resulted in the creation of enough artificial, officially fixated nitrogen that eliminated concerns about the ability to have enough fertilizer to feed the world. Both Fritz-Hobber and Karl Bosch were awarded Nobel Prizes for their work. While nitrogen is vital for agricultural crops, it's possible to have too much of a good thing. When nitrogen fertilizer runs off of agricultural land, it can leach into the water supply and result in what is known as eutrification. Utrification is when a body of water becomes saturated with minerals and nutrients, particularly nitrogen. This can result. in algae blooms, which can deplete the oxygen in the water and kill off most of the life

Starting point is 00:08:36 forms that live in it. While nitrogen fertilizer is an important use of nitrogen, it is far from the only one. In many specialty cases, tires are often inflated with pure nitrogen instead of air. Oxygen can be reactive and moisture in the air can cause excessive expansion and contraction due to temperature. Race cars and airplanes will often inflate tires with nitrogen to solve these problems. And nitrogen tire inflation has even found its way to some commercial gas stations and auto repair centers. Pure nitrogen gas is also used in a host of other applications where unwanted oxidation isn't desired. The process of nitriding is used on metals. Nitriding is a surface hardening process used to improve the hardness and wear resistance of metals, particularly

Starting point is 00:09:19 steel. It involves the diffusion of nitrogen into the surface layers of metal. Nitrogen is also used in some fire suppression systems in lieu of carbon dioxide as well. In the 19th century, one of the first artificial chemical creations using nitrogen was nitroglycerin. It is an extremely highly volatile explosive that was used as the basis for dynamite, which will be the subject of a future episode. One of the most important industrial and commercial uses of nitrogen today is liquid nitrogen. Nitrogen has a boiling point that can be achieved relatively easy with commercial equipment. It will liquefy at negative 196 degrees Celsius, negative 320 degrees Fahrenheit, or 77 Calvin. Liquid nitrogen can be used for medical purposes for the removal of warts and other skin legions.

Starting point is 00:10:07 I actually had this procedure performed on me when I was really young and I had a wart on my hand. They injected a topical anesthesia, froze the effrending wart with liquid nitrogen, which caused the area to eventually shrivel and die. Liquid nitrogen is sometimes used on metal parts to shrink them a tiny amount so that they can fit better together and then expand when they get warm. Many high-end classical musicians give their instruments chryogenic treatments. The process of making an instrument can result in microscopic fractures in the metal. By exposing the instruments to extreme cold temperatures provided by liquid nitrogen, many of the micro-fractures in the metal can heal. And believe it or not,

Starting point is 00:10:44 this technique is also used on woodwinds as well as brass instruments. Liquid nitrogen is used to cool the sensors in high-end astronomy telescopes. It's necessary to remove small heat fluctuations which allow the instruments to become more sensitive to low light conditions. One of the holy grails of physics and material science right now is trying to find a cheap, high-temperature superconductor. While a room-temperature superconductor would be ideal, even one that could operate at the temperature of liquid nitrogen could be made cost-effective for many uses. Some high-end molecular gastronomy restaurants use liquid nitrogen to freeze foods and even to make ice cream. Liquid nitrogen is normally very safe to work with, but it can be very dangerous if used improperly.

Starting point is 00:11:26 When nitrogen boils and becomes a gas, it expands to 694 times the volume from when it was a liquid. In 2006, there was an accident at Texas A&M University involving liquid nitrogen. A large tank of liquid nitrogen had a damaged pressure relief valve that didn't allow the gas to vent. The pressure built up, resulting in a catastrophic explosion which literally blew the tank through the ceiling and broke a concrete beam below it. In 2012, a woman from England was hospitalized and had to have her stomach removed after she drank a cocktail made out of liquid nitrogen. I find nitrogen to be a very odd element. It's everywhere and with us all the time, yet it's very difficult to work with beyond using it in its molecular form. It's absolutely vital for life,

Starting point is 00:12:13 yet most life can't access it directly. It has a variety of industrial and commercial uses, but we couldn't actually extract it from the air until the 20th century. All of these apparent contradictions, I guess, are what make nitrogen so special. The executive producer of Everything Everywhere Daily is Charles Daniel. The associate producers are Peter Bennett and Cameron Kiefer. I wanted to give a big thanks to everyone who supports the show on Patreon. Your support helps me put out a new show every day. And if you're interested in Everything Everywhere Daily merchandise,

Starting point is 00:12:47 Patreon is currently the only place where it's available. And if you'd like to talk to other listeners of the show and get notified, to future episodes and projects, please join my Facebook group or Discord server. Links to everything are in the show notes.

Everything Everywhere Daily: History, Science, Geography & More - Nitrogen

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