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 halogens. What are halogens, and where might you encounter them in your daily life?
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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, astatine is considered one of the rarest naturally occurring elements, and tennessine is an artificially created element.
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?
- Fluorine: You’ve probably encountered fluorine in your toothpaste in the form of sodium fluoride. When paired with hydrogen — one of the hydrogen properties that makes them easy to identify — it becomes hydrofluoric acid that’s used in glass etching. Fluorine in its natural gaseous state is toxic. Just breathing in a breath of air that is 0.1 percent fluorine can kill you. It’s one of the most reactive elements on the planet and will bond with just about anything.
- Chlorine: There’s chlorine in your laundry room right now if you wash your clothes with bleach. Chlorine bleach is popular because of its disinfectant properties. Pools are treated with it as well. Chlorine is also a poisonous gas in its pure form, but in spite of its toxicity, small amounts are necessary for human health, along with fluorine and iodine.
- Bromine: Bromine is a toxic chemical that’s used in agriculture and in some insecticides. It can be used in flame retardants as well, but you probably haven’t encountered it in your daily life. It’s also difficult to store — it will evaporate at room temperature.
- Iodine: Iodine is great as a disinfectant — it stings like mad on open wounds, but it’s effective at killing fungus, bacteria and other microorganisms. When paired with potassium, it becomes potassium iodide, which can be an effective treatment for radiation exposure.
- Astatine: Astatine is another radioactive element that’s sometimes used during cancer treatment. It’s another element that you probably won’t encounter during your daily activities due to its fairly short half-life.
- Tennessine: Tennessine is one element that you won’t encounter unless you work in a nuclear research lab. It was created by scientists who bombarded berkelium with calcium ions until they could detect the new element. They’ve only ever managed to create a few atoms at a time, which decayed so quickly that you definitely won’t find them in your home.
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.