Is Iodine a Metal or Nonmetal? (+ 3 Things to Know)

Iodine is a nonmetal. It is a chemical element with the symbol I and atomic number 53. It belongs to the halogen group on the periodic table, which includes other nonmetals such as fluorine, chlorine, and bromine. ¹

Well, this was just a simple answer. But there are few more things to know about this topic which will make your concept super clear.

So let’s dive right into it.

Why is iodine a nonmetal?

Iodine is classified as a nonmetal because it lacks the physical and chemical properties of a metal. 

Nonmetals are elements that are usually gases or brittle solids and are poor conductors of heat and electricity. They tend to have low melting and boiling points, low densities, and are generally not malleable or ductile. ²

Iodine is a dark, shiny, purple-black solid at room temperature and pressure, and it has a low melting point and boiling point. ³ It is a poor conductor of heat and electricity, and it is not malleable or ductile. These characteristics make it similar to other nonmetals like sulfur and carbon.

In addition to its physical properties, iodine also exhibits chemical properties that are characteristic of nonmetals.

For example, it tends to form covalent bonds with other elements, rather than the metallic bonds that are typical of metals. It also tends to gain electrons in chemical reactions, rather than losing them as metals do. ⁴

Overall, based on its physical and chemical properties, iodine is classified as a nonmetal.

Properties of iodine that classify it as a nonmetal

Iodine exhibits several properties that classify it as a nonmetal:

• Physical state: At room temperature and pressure, iodine is a dark, shiny, purple-black solid. Nonmetals are typically gases or brittle solids at room temperature and pressure, and iodine’s solid state is characteristic of nonmetals.
• Low melting and boiling point: Iodine has a relatively low melting point (113.7 °C) and boiling point (184.3 °C). Nonmetals typically have low melting and boiling points compared to metals, which have high melting and boiling points. ⁵
• Poor conductor of heat and electricity: Iodine is a poor conductor of heat and electricity. This is a characteristic of nonmetals, which do not have free electrons that can carry electrical current.
• Brittle: Iodine is a brittle solid, meaning that it can break or shatter easily when subjected to stress. This property is also typical of nonmetals.
• Low density: Iodine has a relatively low density of 4.93 g/cm³. Nonmetals generally have lower densities than metals, which have higher densities. ^{6 7}
• Covalent bonding: Iodine tends to form covalent bonds with other elements, rather than the metallic bonds that are typical of metals. This is another characteristic of nonmetals.

Tendency to gain electrons: Iodine has a tendency to gain electrons in chemical reactions, rather than losing them as metals do. This property is also typical of nonmetals.

How is iodine different from other nonmetals?

Iodine differs from other nonmetals in several ways:

• Appearance: Iodine is a distinctive purple-black color and has a shiny appearance. Other nonmetals such as sulfur and carbon are not typically this color and do not have a shiny appearance.
• Density: Iodine has a higher density than most other nonmetals, including sulfur and carbon. ⁸
• Biological importance: Iodine is an essential element for human health, and is required for the synthesis of thyroid hormones. This biological importance is not shared by other nonmetals. ^{9 10 11 12}
• Melting and boiling point: While iodine has a relatively low melting and boiling point compared to metals, it has a higher melting and boiling point than many other nonmetals.
• Reactivity: Iodine is less reactive than some other nonmetals such as fluorine and chlorine, which are highly reactive and can even react explosively with certain substances.

Further reading

Is Xenon a Metal?
Is Barium a Metal or Nonmetal?
Is Gold a Metal or Nonmetal?
Is Mercury a Metal or Nonmetal?
Is Lead a Metal or Nonmetal?

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