FormulasChemistry FormulasIodine Formula 

Iodine Formula 

Iodine Formula


    Fill Out the Form for Expert Academic Guidance!


    Live ClassesBooksTest SeriesSelf Learning

    Verify OTP Code (required)

    I agree to the terms and conditions and privacy policy.

    Iodine is a chemical element with the symbol I and atomic number 53. It is a non-metal and belongs to the halogen group on the periodic table. Iodine is known for its distinctive purple-black colour and its characteristic odour. It exists as diatomic molecules, with each molecule consisting of two iodine atoms bonded together, represented by the formula I2.

    Iodine has a variety of applications and significance in various fields. It is commonly used in medicine as an antiseptic for disinfecting wounds and in the treatment of thyroid disorders. Iodine compounds are also utilized in the production of dyes, pharmaceuticals, and photographic materials. Additionally, iodine is an essential nutrient required by the human body for the synthesis of thyroid hormones, which play a crucial role in regulating metabolism.

    Structural Formula of Iodine

    The structural formula of iodine is represented as I2. This formula indicates that iodine is composed of two iodine atoms bonded together through a covalent bond. The symbol “I” represents iodine, and the subscript “2” indicates that there are two iodine atoms in the molecule.

    Uses of Iodine

    1. Medicine and Healthcare: Iodine is used in various medical applications, including disinfectants, antiseptics, and sterilization of medical equipment. It is also an essential component in the production of iodine-based contrast agents used in medical imaging procedures.
    1. Water Treatment: Iodine is used for water disinfection and purification. It is effective against a wide range of microorganisms and is commonly used in emergency situations or for camping and hiking where access to clean water may be limited.
    1. Nutrition and Dietary Supplements: Iodine is an essential nutrient for the human body, and it is added to table salt and other food products to prevent iodine deficiency disorders. It is also used as a dietary supplement to ensure adequate iodine intake.
    1. Chemical Industry: Iodine is used as a precursor in the production of various chemicals and compounds. It is utilized in the manufacturing of pharmaceuticals, dyes, pigments, catalysts, and iodized compounds.
    1. Laboratory and Research: Iodine is widely used in laboratories for various analytical and research purposes. It is utilized in chemical reactions, staining procedures, and as a reagent in laboratory tests.
    1. Photography: Iodine is used in the production of photographic films and papers. It is an essential component in the formation of silver iodide, which is sensitive to light and helps capture images.
    1. Veterinary Applications: Iodine is used in veterinary medicine for disinfection of wounds, treatment of animal diseases, and iodine supplementation for livestock.

    Physical Properties of Iodine Formula

    1. Appearance: Iodine is a solid at room temperature. It has a distinctive deep purple colour, which gives it a visually striking appearance.

    1. Melting Point: Iodine has a relatively low melting point of 113.7 degrees Celsius (236.7 degrees Fahrenheit). At this temperature, solid iodine transforms into a liquid state.

    1. Boiling Point: Iodine has a relatively high boiling point of 184.3 degrees Celsius (363.7 degrees Fahrenheit). At this temperature, liquid iodine vapourizes and becomes a gas.

    1. Density: The density of iodine is 4.93 grams per cubic centimeter. It is denser than water, which has a density of 1 gram per cubic centimeter.

    1. Solubility: Iodine is sparingly soluble in water. It dissolves more readily in organic solvents such as ethanol, diethyl ether, and chloroform.

    1. Sublimation: Iodine exhibits sublimation, which means it can undergo a phase change directly from a solid to a gas without passing through the liquid state. This is commonly observed when solid iodine crystals are heated and produce purple-coloured vapour.

    1. Odour: Iodine has a characteristic odour, which can be described as a pungent and slightly sweet smell.

    Chemical Properties of Iodine Formula

    1. Reactivity: Iodine is a relatively reactive element, especially when exposed to certain conditions or other reactive substances. It readily reacts with many elements and compounds, including metals, non-metals, and halogens.

    1. Oxidizing Agent: Iodine acts as an oxidizing agent in chemical reactions. It can accept electrons from other substances, causing them to undergo oxidation. For example, in the reaction with sodium thiosulfate, iodine oxidizes thiosulfate ions to form tetrathionate ions.

    1. Formation of Ions: Iodine can form ions by gaining or losing electrons. It can form negatively charged iodide ions (I-) by gaining an electron or positively charged iodine cations (I+) by losing an electron.

    1. Halogen Displacement Reactions: Iodine can displace less reactive halogens from their compounds through halogen displacement reactions. For example, iodine can displace chlorine from sodium chloride to form sodium iodide.

    1. Formation of Iodides: Iodine readily reacts with metals to form metal iodides. These iodides can be soluble or insoluble, depending on the specific metal and conditions.

    1. Reaction with Organic Compounds: Iodine can react with organic compounds, especially those containing carbon-carbon double or triple bonds. It can add across these bonds, leading to the formation of iodinated organic compounds.

    1. Complex Formation: Iodine can form complex compounds with certain substances, such as starch. This forms a characteristic blue colour complex, which is often used as a test for the presence of iodine.


    In conclusion, iodine (I2) is a chemical element that exists as a diatomic molecule. It is commonly known for its distinctive purple-black solid form. Iodine has numerous important applications across various industries and sectors. It is widely used in medicine as an antiseptic for disinfection and in the production of pharmaceuticals. Iodine is also utilized in the manufacturing of dyes, pigments, and photographic chemicals. Additionally, it plays a crucial role in the production of iodized salt, which is essential for preventing iodine deficiency disorders. Furthermore, iodine has applications in laboratory research, analytical chemistry, and nuclear medicine. Overall, iodine’s unique properties and versatile nature make it a valuable element with a wide range of uses.

    Solved Examples on Iodine Formula

    Example 1: Calculate the molar mass of iodine (I2).

    Solution: The molar mass of iodine (I2) can be calculated by adding the atomic masses of two iodine atoms.

    Atomic mass of iodine (I) = 126.90 g/mol

    Molar mass of iodine (I2) = 2 × 126.90 g/mol = 253.80 g/mol

    Therefore, the molar mass of iodine (I2) is 253.80 g/mol.

    Example 2: A 0.50 g sample of iodine (I2) reacts completely with excess sodium metal to form sodium iodide (NaI). Calculate the mass of sodium iodide produced.


    First, we need to determine the molar ratio between iodine (I2) and sodium iodide (NaI) using their balanced chemical equation: I2 + 2Na → 2NaI

    From the equation, we can see that one mole of iodine reacts with two moles of sodium iodide.

    Molar mass of iodine (I2) = 253.80 g/mol

    Molar mass of sodium iodide (NaI) = 149.89 g/mol

    Using the molar ratio, we can calculate the moles of iodine:

    Moles of iodine = mass of iodine / molar mass of iodine

    Moles of iodine = 0.50 g / 253.80 g/mol ≈ 0.00197 mol

    From the balanced equation, we know that the molar ratio between iodine and sodium iodide is 1:2. Therefore, the moles of sodium iodide produced will be twice the moles of iodine:

    Moles of sodium iodide = 2 × moles of iodine

    = 2 × 0.00197 mol

    = 0.00394 mol

    Finally, we can calculate the mass of sodium iodide produced:

    Mass of sodium iodide = moles of sodium iodide × molar mass of sodium iodide

    Mass of sodium iodide = 0.00394 mol × 149.89 g/mol ≈ 0.591 g

    Therefore, the mass of sodium iodide produced is approximately 0.591 g.

    Frequently Asked Questions on Iodine Formula

    1: Why is iodine in baby formula?

    Answer: Iodine is added to baby formula to ensure that infants receive an adequate supply of this essential nutrient. Iodine is necessary for the production of thyroid hormones, which play a crucial role in the development and functioning of the brain and nervous system. Infants have a higher iodine requirement compared to adults, as their bodies are growing rapidly and their thyroid glands are still developing.

    2: What is unusual about iodine?

    Answer: One unusual property of iodine is its ability to undergo sublimation. Sublimation is the process by which a substance directly transitions from a solid to a gas phase without passing through the liquid phase.

    In the case of iodine, it has a relatively low boiling point of 184.3 degrees Celsius (357.7 degrees Fahrenheit) and a high vapour pressure at room temperature. This means that when solid iodine is exposed to air or heated, it undergoes sublimation and transforms directly into a purple-coloured gas without melting into a liquid.

    3: Why is iodine stored in a dark bottle?

    Answer: odine is often stored in a dark bottle to protect it from light. Light, especially ultraviolet (UV) light, can cause a photochemical reaction that can degrade iodine over time. This degradation may result in the formation of iodine vapour or other iodine compounds, which can reduce its potency and effectiveness.

    4: What colour is iodine in milk?

    Answer: When iodine is added to milk, it can cause a colour change, turning the milk a yellowish-brown colour. This reaction occurs due to the reaction between iodine and certain components present in the milk, such as proteins and fats.

    5: Which gives no colour with iodine?

    Answer: Glycogen, a polysaccharide storage form of glucose in animals, does not give a colour reaction with iodine. Unlike starch, which forms a deep blue or black colour complex with iodine, glycogen does not have the same affinity for iodine.

    When iodine is added to a solution containing glycogen, there will be no significant colour change observed. The iodine will remain in its original colour (typically dark purple) without forming a distinct complex with glycogen.

    6: Where is iodine found?

    Answer: Iodine is found naturally in the Earth’s crust and seawater. It is primarily obtained from underground deposits of minerals such as caliche ore and brine pools. Iodine-rich soils and rocks can also contribute to the iodine content in groundwater and surface water. Additionally, seaweed and other marine organisms are known to accumulate iodine from seawater, making them a natural source of iodine.

    7: What is I2 called in chemistry?

    Answer: In chemistry, I2 is called “diiodine” or simply “iodine.” It is a molecular form of iodine composed of two iodine atoms bonded together.

    8: Why is it called iodine?

    Answer: The element iodine is named after the Greek word “iodes,” which means violet-colored. This name is derived from the characteristic violet vapor that iodine produces when heated. The element was discovered in 1811 by French chemist Bernard Courtois, who initially referred to it as “substance X.” It was later named iodine to reflect its distinctive violet color and vapor.

    Chat on WhatsApp Call Infinity Learn

      Talk to our academic expert!


      Live ClassesBooksTest SeriesSelf Learning

      Verify OTP Code (required)

      I agree to the terms and conditions and privacy policy.