Important Differences Between lodine and lodide


Iodine is a chemical element with the symbol I and atomic number 53. It is a non-metal, belonging to the halogen group in the periodic table. At room temperature, iodine exists as a shiny purple-black solid that sublimes directly into a violet gas. It is the least reactive of the halogens, and it is relatively rare in the Earth’s crust compared to other elements in its group. Iodine is essential for the production of thyroid hormones, which regulate metabolism. It is commonly used in various applications, including as a disinfectant, in pharmaceuticals, and in the production of certain dyes. Iodine deficiency can lead to serious health issues, making it a crucial element for human health.

Physical Properties of Iodine:

  • State:

Iodine exists as a shiny, purple-black solid at room temperature.

  • Odor:

It has a distinctive, pungent odor.

  • Density:

Its density is around 4.93 grams per cubic centimeter.

  • Melting Point:

Iodine has a relatively low melting point of 113.7 degrees Celsius.

  • Boiling Point:

It sublimes directly from a solid to a violet gas at 184.3 degrees Celsius.

  • Solubility:

Iodine is sparingly soluble in water but dissolves readily in organic solvents like ethanol and chloroform.

  • Crystal Structure:

It crystallizes in a rhombohedral lattice structure.

Chemical Properties of Iodine:

  • Reactivity:

Iodine is less reactive compared to other halogens like chlorine and bromine.

  • Halogen Characteristics:

It belongs to the halogen group and exhibits typical halogen properties.

  • Oxidation States:

Iodine can exhibit various oxidation states, including -1, +1, +3, +5, and +7.

  • Reactivity with Metals:

It reacts with certain metals to form iodides.

  • Reaction with Hydrogen:

Iodine reacts with hydrogen gas to form hydrogen iodide.

  • Reaction with Organic Compounds:

Iodine can react with organic compounds, often undergoing substitution reactions.

  • Complex Formation:

It forms complexes with various metals and can act as a ligand in coordination compounds.

  • Biological Role:

Iodine is essential for the production of thyroid hormones in the human body.

Uses of lodine in real-life

  • Medical Applications:

Iodine is used in the production of antiseptics and disinfectants for wound care and sterilization.

  • Thyroid Health:

Iodine is a crucial component in the production of thyroid hormones, which are essential for regulating metabolism and overall health.

  • Pharmaceuticals:

It is used in the production of certain drugs and medications, particularly those related to thyroid function and radiology.

  • Nutritional Supplements:

Iodine is added to table salt and other food products as a nutritional supplement to prevent iodine deficiency disorders.

  • Radiography:

Iodine-based contrast agents are used in medical imaging procedures like X-rays and CT scans to enhance visibility of internal organs and structures.

  • Dye Production:

Iodine compounds are used in the manufacturing of dyes and stains for textiles and laboratory applications.

  • Photography:

Iodine can be used in photographic processes for sensitizing emulsions.

  • Veterinary Medicine:

It is used in animal health products, such as disinfectants and supplements.

  • Analytical Chemistry:

Iodine is used as a reagent in various analytical techniques, including titrations.

  • Water Treatment:

Iodine-based disinfectants are used to purify water in emergency situations or in regions with limited access to clean water sources.

  • Industrial Applications:

Iodine is used in industries like electronics, optics, and metallurgy.

  • Biotechnology:

It is used in molecular biology techniques, such as DNA staining and protein labeling.


Iodide refers to a chemical compound containing the iodine ion (I⁻). It is the reduced form of iodine, where the iodine atom gains an electron to achieve a stable electronic configuration. Iodide is essential for various biological processes, particularly in the synthesis of thyroid hormones.

In the human body, iodide is actively transported into the thyroid gland, where it is incorporated into thyroid hormones like thyroxine (T4) and triiodothyronine (T3). These hormones play a crucial role in regulating metabolism, growth, and development.

Iodide also finds applications in industries such as pharmaceuticals, where it is used in the production of drugs and medications. Additionally, iodide compounds have applications in analytical chemistry, as well as in the production of photographic materials.

Physical Properties:

  • State:

Iodide compounds can exist in various states, including solid, liquid, or gas, depending on the specific compound and conditions.

  • Color:

Iodide salts are typically white or colorless, while iodine itself is a dark purple-black solid.

  • Solubility:

Most iodide salts are highly soluble in water, forming clear solutions.

  • Density:

The density of iodide compounds can vary widely depending on the specific compound.

  • Melting and Boiling Points:

These values depend on the specific iodide compound. For example, potassium iodide (KI) has a melting point of about 680°C.

Chemical Properties:

  • Redox Reactions:

Iodide ions can undergo redox reactions, readily accepting or donating electrons. For example, iodide ions can be oxidized to iodine (I2) or reduced to iodine anions (I⁻⁻).

  • Reaction with Acids:

Iodide ions can react with strong acids to release iodine gas. For example, with hydrochloric acid (HCl), iodine gas (I2) is liberated.

  • Complex Formation:

Iodide ions can form complexes with various metal ions, leading to the formation of compounds with distinctive properties.

  • Reactivity with Halogens:

Iodide ions can react with other halogens like chlorine (Cl₂) or bromine (Br₂) to form interhalogen compounds.

  • Thermal Stability:

Some iodide compounds may decompose at high temperatures, releasing iodine vapor.

  • Photodissociation:

In the presence of certain wavelengths of light, iodide ions can undergo photodissociation reactions, releasing iodine gas.

  • Reaction with Oxidizing Agents:

Iodide ions can be oxidized by strong oxidizing agents, resulting in the release of iodine.

Uses of lodide in real-life

  • Thyroid Health:

Iodide is a crucial component for the production of thyroid hormones. These hormones play a vital role in regulating metabolism, growth, and development.

  • Medical Treatments:

Potassium iodide (KI) is used in medicine to treat hyperthyroidism and to protect the thyroid gland from the effects of radiation exposure, particularly in nuclear emergencies.

  • Nutritional Supplements:

Iodide is added to table salt (iodized salt) to prevent iodine deficiency disorders. This helps maintain proper thyroid function in populations with limited access to iodine-rich foods.

  • Pharmaceuticals:

Iodide compounds are used in pharmaceuticals for various applications, including antiseptics, contrast agents for medical imaging, and in the synthesis of drugs.

  • Dye Industry:

Iodine and iodide compounds are used in the production of dyes and stains for textiles, paper, and biological samples.

  • Analytical Chemistry:

Iodide ions are employed in various analytical techniques, including titrations and colorimetric assays, to determine the concentration of substances in a sample.

  • Photography:

Iodide compounds were historically used in the development of photographic films and papers.

  • Sterilization:

Iodine-based solutions are used as antiseptics for disinfecting skin and surgical equipment in healthcare settings.

  • Veterinary Medicine:

Iodide compounds are used in the treatment of various animal health conditions, similar to their applications in human medicine.

  • Industrial Processes:

Iodide compounds find applications in industrial processes such as metallurgy, petroleum refining, and chemical synthesis.

  • Food Industry:

Iodide is used as an additive in certain foods and beverages, particularly in the production of iodized salt.

Important Differences Between lodine and lodide

Basis of Comparison



Chemical Form Element Anion (I⁻)
Charge Neutral Negatively Charged (-1)
State at Room Temp. Solid Ionic Compound (e.g., NaI)
Role in Thyroid Health Precursor for Thyroid Hormones Essential for Thyroid Function
Oxidation State Variable -1 (Always)
Electron Configuration [Kr] 4d¹⁰ 5s² 5p⁵ [Kr] 4d¹⁰ 5s² 5p⁶
Natural Occurrence Found in Nature Formed by Iodine and Metals
Applications Medical Treatments, Dyes, etc. Nutritional Supplements, Drugs, etc.
Physical Properties Purple Vapors, Dark Crystals Colorless, Odorless Crystals
Chemical Properties Reacts with Metals, Halogenation Forms Ionic Compounds
Uses Disinfectants, Contrast Agents Iodized Salt, Pharmaceuticals, etc.
Toxicity Toxic in High Doses Generally Considered Safe
Iodine Number (IN) Measure of Iodine Content in Organic Compounds Not Applicable
Environmental Impact Environmental Hazard Generally Considered Safe
Dietary Sources Seafood, Seaweed, Iodized Salt Iodized Salt, Some Foods

Important Similarities Between lodine and lodide

Basis of Comparison



Chemical Origin Both are iodine-based compounds Both involve iodine in some form
Iodine Component Iodine is a component of iodides Iodides contain iodine
Health Relevance Both are important for thyroid function and health Both play a role in thyroid health
Uses Both can have applications in various industries and medical settings Both find applications in different fields
Role in Nutrition Iodine and iodides are used to fortify salt and ensure sufficient iodine intake Iodized salt contains iodide for nutritional purposes
Chemical Behavior Both can participate in chemical reactions and form compounds Both can react with other elements and molecules
Role in Medical Field Both iodine and iodides can be used in medical applications Medical treatments and contrast agents may involve iodine or iodides
Occurrence in Nature Both are found naturally in certain environments Seawater, soil, and some foods contain iodine and iodides
Chemical Form Iodine exists as an element (I₂), while iodides are typically ionic compounds Iodides are ionic compounds formed from iodine and other elements

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