We use the different elements of the periodic table every single day without even realizing it. Oxygen and hydrogen make up the water you drink. Oxygen and nitrogen make up the air you breathe. The various metals make up everything from the silverware you eat with to pieces of the car you drive. Today, we’re going to take a closer look at halogen properties. What are halogens, and where might you encounter them in your daily life?
Halogen Properties and Order of Abundance
There are six elements in the halogen group, but they’re very rarely found in their pure form in nature. These elements are very reactive, so when they’re found in nature, it’s usually in the form of compounds or as ions. The six are:
Fluorine and chlorine are fairly abundant in the Earth’s crust. Iodine and bromine are rarer. Scientists consider astatine one of the rarest naturally occurring elements. On the other hand, scientists artificially created Tennessine.
Chemical and Physical Traits
Each of these elements has similar chemical and physical properties. Halogen properties are identified by their outer shell — each halogen element has seven valence electrons in its outer shell. In their pure form, you’ll never find a single atom of a halogen element. They’re all found as diatomic molecules — two atoms of the element — or bonded with another element.
Each of these elements will also form acids when combined with hydrogen. Unlike some of the other elemental groups, halogens span all three states of matter. Iodine and astatine are found as solids, bromine is found as a liquid, and fluorine and chlorine in their natural state are gasses.
Tennessine is a bit difficult to classify because it was created in a lab, so there have only been a few atoms created at any given time, and the element has a half-life of only around 80 milliseconds.
Where can you find the halogen elements in your daily life? Since the nature of halogen properties makes then hard to find alone, here are common diatomic molecules of each element found in our lives.
Fluorine is a bit of an elemental problem child. It’s the most reactive element on the periodic table, bonding with anything that gets close enough to swap electrons. It also refuses to let go of any of its ill-gotten gains. No chemical on the planet can separate fluorine from any of its compounds. This reactivity means you’ll never find pure elemental fluorine in nature.
There are plenty of applications for this problematic element, and you’ve likely encountered a couple of them in your daily life.
Uses for Fluorine
- Toothpaste: Pair fluorine with sodium, and you get sodium fluoride. You’ll find this compound in most toothpaste as it helps prevent tooth decay.
- Glass etching: Paired with hydrogen, fluorine becomes hydrofluoric acid. This acid is often found in both consumer and commercial glass-etching compounds.
- Uranium isotopes: Fluorine even bonds with radioactive elements. Uranium hexafluoride helps nuclear engineers separate out uranium isotopes for different applications.
Chlorine is another element that happily bonds with nearly anything that crosses its path, though it isn’t as reactive as fluorine. The element dates back to the late 1700s, and most of the chlorine we use today comes from the oceans via electrolysis.
You’ll find chlorine in all sorts of different products — many of which you probably have in your home right now.
Uses for Chlorine
- Cleaners: Bleach is made from diluted chlorine. Its antiseptic properties make it valuable for everything from disinfecting surfaces to purifying drinking water.
- Swimming pools: Another application for chlorine is swimming pool maintenance. The element sanitizes the water and prevents algae and bacterial growth.
- Table salt: Take two dangerous chemicals — sodium and chlorine — and allow them to bond, and you’ve got a tasty addition to most foodstuffs. Sodium chloride is the chemical name for table salt.
Bromine and Iodine
Bromine gets its name from the Greek word bromos, which means stench. This element is liquid at room temperature and has an incredibly noxious smell. It’s a dangerous substance, causing chemical burns if it comes into contact with your skin. It will also evaporate at room temperature, creating a halogen gas that will irritate the eyes and lungs.
Iodine, on the other hand, was another accidental discovery. A chemist was trying to remove sodium and potassium from seaweed. Adding too much sulfuric acid to the compound released a cloud of purple gas that, when condensed, contained elemental iodine.
Uses for Bromine and Iodine
- Photo development: Bromine used to be necessary to keep lead from building up in engines when we still used leaded gasoline. Today, unleaded is standard, and the only practical use for bromine is in the form of silver bromide, which is necessary for developing photographs.
- Disinfectants: Iodine mixed with alcohol is an incredibly effective antiseptic for superficial wounds. These days, it’s not as common as it once was, but you can still find a bottle or two in your local pharmacy.
- Radiation exposure: Iodine is a necessary micronutrient that supports thyroid health. When it bonds with potassium, the resulting potassium iodide can treat acute radiation exposure.
Astatine and Tennessine
Astatine is so incredibly rare in nature that scientists estimate only 30 grams exist at any given time. It forms when thorium and uranium decay.
Tennessine doesn’t occur naturally, but it is incredibly radioactive. It has an incredibly short half-life — around 80 milliseconds — so you won’t find it in your daily life. Outside of laboratory settings, there are no practical uses for either of these elements.
Second to Last, but not Least
The halogen group might not be as common as some of the other element groups, but these elements are an essential part of the world around us, and many of them are the basis for things like the bleach in your laundry room or the toothpaste in your bathroom. You might not encounter them in their pure form, but in the case of things like fluorine and chlorine, that’s not a bad thing. If you’ve got iodine in your first aid kit, you’ve encountered halogens in your daily life.