Discuss Halogen elements with reference to the following:(a) Position in the periodic table(b) Physical state of elements(c) Electron gain enthalpy(d) Electronegativity(e) Formation of interhalogen compounds

by

Points to Remember:

  • Halogens are Group 17 elements.
  • They are highly reactive non-metals.
  • They exhibit a gradation in properties down the group.
  • Interhalogen compounds are formed between different halogen atoms.

Introduction:

Join Our Telegram Channel

Halogens, meaning “salt-formers,” are a group of non-metal elements found in Group 17 (VIIA) of the periodic table. They include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Their reactivity stems from their electron configuration, possessing seven valence electrons, making them one electron short of a stable octet. This drives their strong tendency to gain an electron, forming negatively charged ions (halide ions). Their properties show a clear trend as we move down the group, with fluorine being the most reactive and astatine the least.

Body:

(a) Position in the Periodic Table:

Halogens occupy Group 17 of the periodic table. This group is characterized by elements having the general electronic configuration ns²np⁵, where n represents the principal quantum number. Their position dictates their chemical behavior, specifically their high electronegativity and strong oxidizing power.

(b) Physical State of Elements:

At room temperature, the physical states of halogens vary:

  • Fluorine (F₂) and Chlorine (Cl₂) are gases.
  • Bromine (Br₂) is a liquid.
  • Iodine (I₂) is a solid.
  • Astatine (At) is a solid, but its properties are less well-known due to its radioactivity and short half-life.

This variation is due to the increasing strength of van der Waals forces with increasing atomic size and mass down the group.

(c) Electron Gain Enthalpy:

Electron gain enthalpy refers to the energy change when an atom gains an electron. Halogens have highly negative electron gain enthalpies, indicating a strong tendency to accept an electron. However, there is a slight decrease in the magnitude of electron gain enthalpy down the group. Fluorine, despite having the highest electronegativity, has a less negative electron gain enthalpy than chlorine. This anomaly is attributed to the small size of the fluorine atom, leading to increased electron-electron repulsion in the relatively compact 2p subshell.

(d) Electronegativity:

Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond. Halogens exhibit high electronegativity, with fluorine being the most electronegative element. Electronegativity decreases down the group, reflecting the increasing atomic size and decreasing nuclear attraction for valence electrons. This trend explains the decreasing reactivity down the group.

(e) Formation of Interhalogen Compounds:

Subscribe on YouTube

Interhalogen compounds are formed between two different halogen atoms. They have the general formula XYₙ, where X is the less electronegative halogen and Y is the more electronegative halogen, and n can be 1, 3, 5, or 7. Examples include ClF, BrF₃, IF₅, and IF₇. The formation of these compounds is due to the difference in electronegativity between the halogens, leading to the formation of polar covalent bonds. The size difference between the halogens also plays a role in determining the structure and stability of the interhalogen compounds. These compounds are often highly reactive and strong oxidizing agents.

Conclusion:

Halogens are a unique group of elements exhibiting a clear trend in their properties down the periodic table. Their high electronegativity and electron gain enthalpy make them highly reactive non-metals. The variation in their physical states, coupled with the formation of interhalogen compounds, highlights the diverse chemistry of this group. Understanding these properties is crucial in various applications, including industrial processes, synthesis of new materials, and even in biological systems. Further research into the less understood aspects of astatine and the applications of interhalogen compounds holds potential for future advancements in various fields. A holistic approach to studying halogens, considering their environmental impact and safe handling procedures, is essential for responsible scientific progress.

CGPCS Notes brings Prelims and Mains programs for CGPCS Prelims and CGPCS Mains Exam preparation. Various Programs initiated by CGPCS Notes are as follows:-

error: Content is protected !!