Question

Match the following (a) \(\mathrm{F}_{2}\) (p) pale yellow coloured gas (b) \(\mathrm{Cl}_{2}\) (q) violet colour solid (c) \(\mathrm{Br}_{2}\) (r) orange red liquid (d) \(\mathrm{I}_{2}\) (s) greenish coloured gas

Short answer

(a) (p), (b) (s), (c) (r), (d) (q).

Step-by-step solution

Understanding the Chemistry

The given exercise requires matching halogens to their characteristic physical states and colors at room temperature. We need to identify the typical appearance of each halogen: fluorine (F_{2}), chlorine (Cl_{2}), bromine (Br_{2}), and iodine (I_{2}).

Identify Fluorine Properties

Fluorine (F_{2}) is known as a pale yellow coloured gas. This matches description (p).

Identify Chlorine Properties

Chlorine (Cl_{2}) is a greenish-coloured gas. This matches description (s).

Identify Bromine Properties

Bromine (Br_{2}) is an orange-red liquid at room temperature. This matches description (r).

Identify Iodine Properties

Iodine (I_{2}) is a violet coloured solid. This matches description (q).

Match the Elements with Their Properties

Using the identifications from the previous steps, we match each halogen with its corresponding property: - (a) F_{2} corresponds to (p) pale yellow coloured gas. - (b) Cl_{2} corresponds to (s) greenish coloured gas. - (c) Br_{2} corresponds to (r) orange red liquid. - (d) I_{2} corresponds to (q) violet colour solid.

Key concepts

Fluorine

Fluorine is the most reactive element on the periodic table and is found in the halogen group. It is represented by the chemical formula \( \text{F}_2 \). At room temperature, fluorine is a pale yellow gas with a pungent smell.

Fluorine's extreme reactivity is due to its high electronegativity and small atomic size, which make it highly eager to form bonds with other elements. This reactivity means handling fluorine requires special precautions to avoid reactions with other materials.

Some everyday applications of fluorine include fluoride toothpaste and Teflon coatings. Despite its reactivity, fluorine plays a vital role in dental health and non-stick cookware.

Chlorine

Chlorine is a halogen represented by \( \text{Cl}_2 \). It is a greenish colored gas at room temperature, known for its strong, irritating smell.

Chlorine is widely used due to its disinfectant properties. It is commonly found in swimming pool sanitation and household bleach. Its ability to kill bacteria and other microbes makes it invaluable for water purification.

Beyond disinfection, chlorine is used in the production of various consumer products, including PVC plastic. As a powerful oxidizing agent, chlorine plays a crucial role in many industrial processes.

Bromine

Bromine, noted for its unique characteristics, appears as \( \text{Br}_2 \). Unlike other halogens, bromine is a liquid at room temperature with an orange-red color.

While less volatile than chlorine, bromine's high density and ability to evaporate quickly at room temperature can create fumes that are potentially harmful if inhaled. This makes handling bromine with care important.

Bromine is extensively used in flame retardants, which are essential in preventing fires in a variety of consumer products. It also plays a part in pharmaceuticals, photography, and certain types of water purification.

Iodine

Iodine, represented as \( \text{I}_2 \), is the least reactive of the common halogens but still holds essential applications in many fields. At room temperature, iodine is a violet-colored solid.

This element sublimates easily, turning from solid to violet gas without passing through a liquid state. Iodine's antiseptic properties make it valuable for medical use as a disinfectant.

In our diet, iodine is a critical trace element necessary for the production of thyroid hormones. Iodized salt is a common source, helping to ensure that populations consume adequate iodine levels to prevent deficiencies.