In a covalent molecule containing halogen atoms, the property of attracting shared electrons towards the halogen atoms is called what?

Introduction / Context:
Halogens such as fluorine, chlorine, bromine and iodine are well known for their strong tendency to attract electrons in chemical bonds. This tendency influences bond polarity, molecular shape and reactivity. Several related terms are used in chemistry, including electron affinity and electronegativity, and it is important to distinguish between them. This question asks for the name of the property that describes how strongly an atom in a molecule attracts shared electrons in a covalent bond, which is crucial for understanding polar covalent bonds and partial charges.

Given Data / Assumptions:

• We are dealing with covalent molecules where atoms share electron pairs.
• Halogen atoms usually have high attraction for shared electrons in bonds.
• Electron affinity is a separate concept, referring to energy change when an isolated gaseous atom gains an electron.
• Electropositivity refers to the tendency of an atom to lose electrons and form cations.
• We assume basic knowledge of terms used in periodic trends.

Concept / Approach:
Electronegativity is defined as the ability of an atom in a molecule to attract the shared electron pair towards itself in a covalent bond. It is a relative scale without units, with fluorine as the most electronegative element. This property is responsible for bond polarity, where one end of a bond becomes partially negative and the other partially positive. Electron affinity, in contrast, is an energy change for an isolated atom, not specifically for a bonded atom in a molecule. The correct approach is to choose the term that matches attraction for shared electrons in a bond, which is electronegativity.

Step-by-Step Solution:
Step 1: Identify the property being described: attraction for electrons in a covalent bond, not energy change for an isolated atom. Step 2: Recall that electronegativity is defined as the tendency of an atom in a molecule to attract the shared pair of electrons toward itself. Step 3: Recognise that halogens are high in electronegativity because they are close to completing their valence octet. Step 4: Electron affinity refers to the energy released or absorbed when a gaseous atom gains an extra electron, which is a different concept from electronegativity. Step 5: Electropositivity is the tendency of an element, usually a metal, to lose electrons and become a cation, which is the opposite behaviour of halogens. Step 6: Electrochemistry and electrical conductivity are branches and properties related to charge transfer and flow, not directly to electron attraction in covalent bonds. Step 7: Thus the correct term for the electron attracting property of halogen atoms in a molecule is electronegativity.

Verification / Alternative check:
Periodic tables often list electronegativity values alongside atomic numbers. Fluorine has the highest electronegativity, followed by oxygen, chlorine and so on. Halogens consistently show high electronegativity values, reflecting their strong pull on shared electrons. Bond polarity diagrams, which show partial charges, are based on differences in electronegativity between atoms in a bond. In contrast, tables of electron affinities show energy changes for adding electrons to isolated atoms, which is related but not the same as behaviour in a bonded state. This confirms that electronegativity is the property needed in this question.

Why Other Options Are Wrong:
Option A, electron affinity, describes the energy change when an isolated gaseous atom accepts an electron and is not defined specifically for atoms in molecules. Option B, electropositivity, refers to the tendency to lose electrons and is high for alkali metals, not for halogens. Option C, electrochemistry, is a branch of chemistry studying redox reactions and cells, not a property of atoms. Option E, electrical conductivity, describes how well a substance conducts electric current, which is not the same as attraction for shared electrons. Only option D, electronegativity, correctly names the property by which halogen atoms attract shared electrons in a covalent bond.

Common Pitfalls:
Students often confuse electron affinity and electronegativity because both involve attraction for electrons and show similar periodic trends. The key distinction is that electron affinity is about isolated atoms and energy changes, while electronegativity is about atoms that are part of a molecule and their influence on shared electron pairs. Another pitfall is to equate electropositivity simply with low electronegativity, but they are used in different contexts. Making clear mental definitions for each term and linking electronegativity specifically to covalent bonds will help avoid mistakes.

Final Answer:
The property of attracting shared electrons towards halogen atoms in a molecule is called Electronegativity.