What Is Bromine? Physical and Chemical Properties Explained
When you think about Bromine, you may imagine something reddish-brown. Gases containing bromine atoms have not such pleasing colours, have a foul smell, and they can irritate your nose and skin. The name bromine has derived from the Greek word ‘Bromos,’ which means something that smells bad. Its symbol is ‘Br’, and the bromine atomic number is 35. It’s a member of the halogen family of elements; fluorine, chlorine, and iodine are its companions. The Br element can cause serious health problems to humans. Nonetheless, it still is highly useful in our lives. Balard found this element in 1826. One of the fascinating things about Bromine is that it’s the only non-metallic element which is a liquid at room temperature. You can learn about properties, uses, and facts about Bromine further in this article.
What is Bromine?
Bromine is a chemical element with a fuming brown-red liquid. The noxious liquid is a member of the halogen family of the periodic table. It is the third-biggest halogen with an exceptional vapour pressure at room temperature. And it’s the only non-metallic element that stays in a liquid state at room temperature.
Physical Properties of Bromine
Before we move onto some unique properties of Br element, below are some fundamental physical properties.
Bromine belongs to the group – 17, period – 4, and block – p.
Bromine electron configuration is [Ar] 3d¹⁰ 4s² 4p⁵, and its atomic number is 35.
Its melting point is −7.2°C, 19°F, 266 K and boiling point is 58.8°C, 137.8°F, 332 K.
The relative atomic weight is 79.904, and it has a density of (g cm-3) 3.1028.
The appearance of an element is reddish-brown, and it has metallic lustre in solid-state.
Bromine has 29 known isotopes; it ranges from Br-69 to Br-97. And there are two stable isotopes Br-79 and Br-81.
Chemical Properties of Bromine
Bromine has significantly high electron affinity, which is equivalent to chlorine. However, the oxidizing power of bromide is relatively low as bromide ion has weaker hydration than chloride ion.
Bromine gels violently with alkali metals and with aluminium, arsenic, phosphorus and antimony. But it combines less violently with other particular metals.
Bromine tends to displace hydrogen from saturated hydrocarbons and adds it to unsaturated hydrocarbons, but not as seamlessly as chlorine does.
Bromine has high first ionization energy and compounds that contain Bromine get stabilized by appropriate ligands, primarily oxygen and fluorine. Compounds having oxidation numbers +1, +3, +4, +5, and +7 all have covalent bonds.
Uses of Bromine
Right from the discovery of Bromine, its compounds have a majority of applications across different industries. Below are some important purposes that bromine servers.
Water Purification: Purifying or disinfecting the water is a major use of Bromine. It serves as an alternative to chlorine. Brominated compounds get used to treating water in swimming pools and hot tubs. It also helps prevent algae and bacterial growth in industrial processes.
Pesticides: As you know that Bromine is poisonous to the human body, it also has a major application in pesticides. It can efficiently control insect infestations.
Healthcare: Brominated substances are an essential ingredient of over-the-counter and prescription drugs, which includes analgesics, antihistamines, and sedatives. Some drugs have been successful in treating pneumonia and cocaine addiction.
Photography: Many liquids get used to developing perfect photographs. Bromine compounds get used to making a vital light-sensitive part of a photographic emulsion. A picture wouldn’t be able to capture adequate light if not for bromine compounds. They also help with photo development.
Plastics: You must know that all plastics are not the same; you can say so by looking at your toys and other devices in your home. There is a unique plastic which is flame resistant. And Bromine gets used to manufacturing those flame-resistant products.
Few Facts About Bromine
Elemental Bromine is poisonous, and it causes corrosion burns upon contact with the skin. Also, inhalation in low concentration lead to irritation and inhaling in higher concentration can cause death too.
Bromine ranks 64th in the list of most abundant elements found in earth’s crust, having an abundance of 2.4 mg/kg.
Elemental Bromine has a reddish-brown colour and a liquid state at room temperature. Mercury is the only other element that has a liquid state at room temperature.
FAQs on Bromine: Key Properties, Uses, and Facts
1. What is bromine and where is it commonly found?
Bromine (symbol Br, atomic number 35) is a chemical element belonging to the halogen group. It is the only nonmetallic element that is a liquid at room temperature, appearing as a dense, reddish-brown fluid that readily evaporates into a similarly coloured gas with a strong, bleach-like odour. Bromine is not found freely in nature but occurs as bromide salts in the Earth's crust and, most abundantly, dissolved in seawater, salt lakes, and underground brines.
2. What are the key physical and chemical properties of bromine?
Bromine has several distinct properties that define its behaviour and uses. Key properties include:
- Physical Properties: It is a dense (3.1 g/cm³), reddish-brown liquid with a relatively low boiling point of 58.8°C and a melting point of -7.2°C. It is moderately soluble in water but highly soluble in organic solvents like carbon tetrachloride.
- Chemical Properties: As a halogen, bromine is highly reactive and a strong oxidising agent, though less powerful than chlorine. It readily combines with most metals and many non-metals. It also participates in substitution and addition reactions with organic compounds.
3. Why is bromine a liquid at room temperature, unlike chlorine (a gas) and iodine (a solid)?
The physical state of halogens at room temperature is determined by the strength of the intermolecular van der Waals forces between their diatomic molecules (e.g., Br₂). As you move down the halogen group from chlorine to iodine, the number of electrons per molecule increases. This leads to stronger temporary dipoles and thus stronger van der Waals forces. For chlorine, these forces are too weak to hold the molecules together as a liquid at room temperature. For iodine, they are strong enough to hold the molecules in a fixed solid lattice. Bromine's intermolecular forces are of intermediate strength, sufficient to keep it in a liquid state but not strong enough to make it a solid.
4. How does bromine differ from chlorine when used as a water disinfectant?
While both are effective disinfectants, bromine has key advantages, especially for hot tubs and spas. The main differences are:
- Stability: Bromine is more stable than chlorine at higher temperatures and in a wider pH range, making it more effective in heated water.
- Byproducts: When bromine combines with organic waste, it forms bromamines. While less potent than bromine itself, bromamines are still effective disinfectants and have a much less pungent odour than the chloramines formed by chlorine.
- UV Sensitivity: Bromine is less susceptible to degradation by ultraviolet (UV) light from the sun compared to chlorine, making it last longer in outdoor pools.
5. What are the most important industrial and commercial uses of bromine?
Bromine and its compounds are vital in various industries. The most significant applications include:
- Fire Retardants: Brominated flame retardants (BFRs) are widely used in plastics for electronics, textiles, and furniture to reduce fire hazards.
- Water Treatment: It is used as a disinfectant for swimming pools, spas, and industrial water systems.
- Pharmaceuticals: Many drugs, including sedatives, antihistamines, and analgesics, contain bromine in their chemical structure.
- Agriculture: Bromine compounds are used as pesticides and fumigants to protect crops and stored grain.
- Photography: Silver bromide (AgBr) is a light-sensitive compound crucial for traditional photographic films and papers.
6. What makes bromine a strong oxidising agent?
Bromine's power as an oxidising agent stems from its atomic structure and position in the periodic table. As a halogen in Group 17, a bromine atom has seven valence electrons. It has a very strong tendency to gain one more electron to achieve the stable electron configuration of a noble gas (krypton). This high electron affinity and electronegativity mean it readily accepts electrons from other substances, thereby oxidising them while it gets reduced itself. This fundamental drive for stability is what makes it highly reactive and a powerful oxidising agent.
7. What are the potential health hazards associated with elemental bromine?
Elemental bromine is highly toxic and corrosive. Exposure can cause severe health issues depending on the concentration and duration. Direct contact with the skin can lead to painful chemical burns and sores. Inhaling bromine vapour is particularly dangerous as it severely irritates the respiratory tract, causing coughing, shortness of breath, and damage to the lungs. It also irritates the mucous membranes of the eyes and throat, causing immediate discomfort and potential long-term damage.
