Problem 153 - A Complete Resource Book in Chemistry for JEE Main

Question

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

Step-by-Step Solution

Answer

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

Step 1: Identify Characteristics

Recognize the unique physical states and colors of the substances in Column-I: - \( \mathrm{F}_{2} \) is a pale yellow gas.- \( \mathrm{Cl}_{2} \) is a greenish-yellow gas.- \( \mathrm{Br}_{2} \) is an orange-red liquid.- Iodine, I, is typically a violet solid.

Step 2: Match Column-I with Column-II

Using the characteristics identified in Step 1, match each Column-I substance to its corresponding physical property in Column-II:- \( \mathrm{F}_{2} \) matches with option (p) pale yellow coloured gas.- \( \mathrm{Cl}_{2} \) matches with option (s) greenish coloured gas.- \( \mathrm{Br}_{2} \) matches with option (r) orange red liquid.- Iodine (I) matches with option (q) violet colour solid.

Key Concepts

Halogens

The group of elements known as halogens includes fluorine ( ext{F}_2), chlorine ( ext{Cl}_2), bromine ( ext{Br}_2), and iodine ( ext{I}_2). Halogens are situated in Group 17 of the periodic table. Each halogen contains seven valence electrons, making them highly reactive. They readily form bonds to complete their electron shells, typically by gaining an electron to form negative ions or by sharing electrons.

• Fluorine is the most reactive of the halogens, and it's known to react, often explosively, with many substances.
• Chlorine, while less reactive than fluorine, is still highly reactive and is well-known for its role in disinfection.
• Bromine and iodine exhibit even lower reactivity but are still good oxidizing agents.

The trend in reactivity among the halogens can be explained by their ability to gain an electron, a property that decreases from fluorine to iodine.

Physical Properties of Elements

Understanding the physical properties of elements, such as color, state, and reactivity, provides insight into their behavior and uses. Each element’s physical properties are influenced by its atomic structure, including the arrangement of electrons.

• Color: The visible color of an element can help identify it. For example,  ext{F}_2 is pale yellow, while  ext{I}_2 is violet.
• State: Elements can be gaseous, liquid, or solid at room temperature. Halogens exhibit all three states:
  • Fluorine and chlorine are gases.
  • Bromine is a liquid.
  • Iodine is a solid.
• Reactivity: The reactivity of an element can determine its applications and how it is handled in a laboratory setting.

These physical properties help chemists and scientists predict how elements will react under different conditions.

Elemental States and Colors

The physical states and colors of elements not only contribute to their identification but also to their applications and handling. Halogens display a fascinating range of physical states and colors.

Identification through Color

Elements often exhibit distinct colors that can be tied to their chemical structure.  ext{F}_2 is pale yellow,  ext{Cl}_2 appears greenish-yellow,  ext{Br}_2 manifests as an orange-red liquid, and  ext{I}_2 is found as a violet solid. These differences are due to the different ways electrons absorb and emit light.

Solid, Liquid, and Gas

The state of an element at room temperature can tell scientists how it might be used and what precautions might be necessary when handling it. Gaseous  ext{F}_2 and  ext{Cl}_2 require cautious handling due to their reactivity as gases, while liquid  ext{Br}_2 and solid  ext{I}_2 can be handled with more straightforward containment measures but still require caution due to their reactive nature.

Applications

The diverse states and colors of elements like the halogens have direct implications for their practical applications, from industrial uses to laboratory research. Their color and reactivity guide their utility, ensuring proper application and safety measures.