In periodic table trends, which of the following elements has the lowest electronegativity value among the choices given?

Introduction / Context:
Electronegativity is a key periodic trend that describes how strongly an atom attracts electrons in a chemical bond. It plays an important role in predicting bond polarity, molecular structure, and reactivity. Across periods and down groups, electronegativity follows predictable patterns. This question asks which element from a small set has the lowest electronegativity value.

Given Data / Assumptions:
- The elements listed are bromine, fluorine, carbon, and lithium. - Fluorine is located in Group 17 (halogens) in Period 2. - Bromine is a halogen in Period 4. - Carbon is a nonmetal in Group 14 and Period 2. - Lithium is an alkali metal in Group 1 and Period 2.

Concept / Approach:
Electronegativity generally increases across a period from left to right and decreases down a group in the periodic table. Nonmetals, especially halogens, are highly electronegative, while alkali metals have low electronegativity. Fluorine is famously the most electronegative element. On the other hand, lithium, located on the far left of Period 2, has a relatively low electronegativity compared to the others in the list. Using these trend rules, we can identify lithium as the element with the lowest electronegativity among the given options.

Step-by-Step Solution:
Step 1: Recall the general trend: electronegativity increases from left to right and decreases from top to bottom. Step 2: Recognise that fluorine is the most electronegative element in the periodic table, so it cannot have the lowest electronegativity. Step 3: Bromine is a halogen lower in the same group as fluorine, so it is still quite electronegative, though less than fluorine. Step 4: Carbon is a nonmetal in the upper right part of the table, giving it a moderate to high electronegativity value. Step 5: Lithium is an alkali metal at the far left of Period 2. Alkali metals have low electronegativity because they prefer to lose their single valence electron. Step 6: Compare all four and conclude that lithium has the lowest electronegativity among the options listed.

Verification / Alternative check:
Approximate electronegativity values on the Pauling scale support this conclusion. Fluorine has a value of about 3.9, bromine about 2.8, carbon about 2.5, and lithium about 1.0. Clearly, lithium has the smallest numerical value, confirming it is the least electronegative element in this group. These values are consistent across standard chemical references and confirm the periodic trend reasoning.

Why Other Options Are Wrong:
Option A (Bromine) is a halogen with relatively high electronegativity compared to metals and many other nonmetals, so it is not the lowest. Option B (Fluorine) is the most electronegative element in the periodic table, so it is the opposite of the correct answer. Option C (Carbon) has a moderate electronegativity but is still significantly more electronegative than lithium.

Common Pitfalls:
Students sometimes mix up electronegativity with other properties such as ionisation energy or atomic radius. Another common mistake is to assume that all nonmetals are automatically more electronegative than all metals without checking specific positions in the periodic table. While this is often true, it is always safer to recall the exact trend and, when possible, approximate values. Remembering that alkali metals like lithium have very low electronegativity values helps avoid confusion.

Final Answer:
The correct answer is: Lithium.