Question

What is the physical state of iodine at room temperature?

Answer 1

Hint: Iodine belongs to the seventeenth group of the periodic table. While moving down the group it comes after bromine. The physical state of any substance depends on the intermolecular forces of attraction between its molecules. Iodine has the largest atomic radii among all halogens.

Complete answer:
Iodine is the element of the ${17}^{th}$ group of the modern periodic table. In a group while moving down the atomic radii increase and iodine has the largest atomic radii among all halogens. Also The atomic number of iodine is $53$ . The atomic mass of iodine is $127\text{ a}\text{.m}\text{.u}$ which is the largest among all halogens. We know that Vander wall forces of attraction depend on the mass of the element. Thus it has high Vander wall forces of attraction. Therefore the physical state of iodine at room temperature is solid. Indeed bromine is liquid and others are in gaseous state. Iodine is present in solid as it has high molecular mass and has a high intermolecular force of attraction. The atoms of iodine are closer to each other as compared to other halogens. Also it exists in orthorhombic structure. Therefore the iodine is in solid state at room temperature.

Note:
The iodine molecules are linked to each other and thus form an orthorhombic crystal at room temperature. When it is heated the crystal breaks down. The boiling point of iodine is also greater than the rest of the halogens. The hydride of iodine is also used as a reducing agent in various organic reagents. Also iodine has some antiseptic properties which makes its use in making soaps and body creams.