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) \(\bar{I}_{2}\) 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: Analyze Column-I Options

Examine the options in Column-I for their physical state and color:(a) \(\mathrm{F}_{2}\) is a pale yellow gas.(b) \(\mathrm{Cl}_{2}\) is a greenish-yellow gas.(c) \(\mathrm{Br}_{2}\) is an orange-red liquid.(d) \(\mathrm{\bar{I}_{2}}\) is a violet or dark purple solid.

Step 2: Analyze Column-II Options

Analyze the colors and states presented in Column-II:(p) Pale yellow gas is matched with \(\mathrm{F}_{2}\).(q) Violet solid is matched with \(\mathrm{\bar{I}_{2}}\).(r) Orange red liquid is matched with \(\mathrm{Br}_{2}\).(s) Greenish gas is matched with \(\mathrm{Cl}_{2}\).

Step 3: Match Column-I to Column-II

Using the analysis from the previous steps, establish the correspondences:- (a) \(\mathrm{F}_{2}\) matches with (p) pale yellow gas.- (b) \(\mathrm{Cl}_{2}\) matches with (s) greenish colored gas.- (c) \(\mathrm{Br}_{2}\) matches with (r) orange red liquid.- (d) \(\mathrm{\bar{I}_{2}}\) matches with (q) violet colored solid.

Key Concepts

Physical properties of halogens

Halogens are a fascinating group of elements found in Group 17 of the periodic table. They have notable physical properties that help in easily distinguishing them from one another. Each halogen exists in different physical states at room temperature:

• Fluorine (\(\mathrm{F}_{2}\)): A pale yellow gas.
• Chlorine (\(\mathrm{Cl}_{2}\)): A greenish-yellow gas.
• Bromine (\(\mathrm{Br}_{2}\)): An orange-red liquid.
• Iodine (\(\bar{\mathrm{I}}_{2}\)): A violet solid.

These unique colors and states of matter are due to the differing strengths of intermolecular forces and molecular weights among the halogens. As you move down the group from fluorine to iodine, the elements change from gases to liquids to solids, highlighting an increase in molecular interactions.

Chemical bonding

Understanding chemical bonding in halogens is key to grasping their behavior. Halogens are diatomic molecules, meaning they consist of two atoms bonded together. They have seven valence electrons, which makes them highly reactive as they strive to attain a complete octet by gaining one more electron. This drive to achieve stability often leads them to form covalent bonds with other nonmetals or ionic bonds with metals. For example:

• Fluorine reacts vigorously with many elements because it is the most electronegative.
• Chlorine can form compounds such as hydrogen chloride (HCl) when it bonds covalently with hydrogen.

These bonds significantly impact the properties of halogen-containing compounds, making halogens essential in many chemical reactions.

Color and state of matter

The stunning colors and distinct states of halogens arise from their molecular structures and the way electrons absorb and emit light. Fluorine appears as a pale yellow gas due to the scattering of light by its small molecules. Chlorine's greenish hue is also an outcome of light interaction with its gaseous form. Bromine is unique among the halogens as a liquid, exhibiting a reddish-orange color due to light absorption and reflection by its denser form. Iodine, on the other hand, exists as a violet solid because of its larger, more complex molecular structure, which affects how it interacts with light.
The vibrant colors and various states of halogens are not just visually captivating but also provide clues about their chemical behavior and interactions, making these elements crucial for scientific exploration and applications.