Problem 63 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following has the highest electronegativity? (a) \(\mathrm{K}\) (b) \(\mathrm{B}\) (c) \(\mathrm{Cl}\) (d) \(\mathrm{Na}\)

Step-by-Step Solution

Answer

Chlorine (Cl) has the highest electronegativity.

Step 1: Understand Electronegativity

Electronegativity is a measure of an atom's ability to attract and hold onto electrons. In the periodic table, electronegativity generally increases across a period from left to right and decreases down a group.

Step 2: Locate the Elements on the Periodic Table

Identify where each of the elements is located on the periodic table: - \(K\) (Potassium) is in Group 1, Period 4.- \( ext{B}\) (Boron) is in Group 13, Period 2.- \( ext{Cl}\) (Chlorine) is in Group 17, Period 3.- \( ext{Na}\) (Sodium) is in Group 1, Period 3.

Step 3: Analyze Electronegativity Trends

From the location of the elements, compare their positions:- \( ext{Cl}\) is to the far right of the periodic table, indicating a higher electronegativity.- \( ext{B}\) is to the right but above \( ext{Na}\) and \( ext{K}\).- \( ext{Na}\) and \( ext{K}\) are on the far left, typically having lower electronegativities.

Step 4: Recall Electronegativity Values

The known electronegativity values are:- \( ext{Cl}\) (Chlorine) has an electronegativity of about 3.16.- \( ext{B}\) (Boron) has an electronegativity of about 2.04.- \( ext{Na}\) (Sodium) has an electronegativity of about 0.93.- \( ext{K}\) (Potassium) has an electronegativity of about 0.82.

Step 5: Determine the Element with the Highest Electronegativity

Compare the electronegativity values of the given elements. Chlorine, with an electronegativity of 3.16, has the highest value among the elements listed.

Key Concepts

Periodic Table

The periodic table is a crucial tool in understanding chemical elements and their properties. It is organized into rows called periods and columns known as groups. Each element's position in the table provides valuable information about its atomic structure and behavior.
The periodic table consists of:

• Groups: Vertical columns that contain elements exhibiting similar chemical behaviors. For example, elements in Group 1 (alkali metals) are highly reactive.
• Periods: Horizontal rows where electronegativity usually increases from left to right. Elements in the same period have the same number of electron shells.

The elements are ordered by increasing atomic number, which tells the number of protons in an atom's nucleus. Understanding the layout helps predict how elements might interact in chemical reactions.

Electronegativity Trends

Electronegativity is an essential concept in chemistry. It refers to an atom's ability to attract electrons when it forms a chemical bond. In the periodic table, electronegativity trends are intriguing and critical to understanding element behavior.
General trends include:

• Across a Period: Electronegativity tends to increase from left to right. This is because the number of protons increases, intensifying the pull on shared electrons.
• Down a Group: Electronegativity decreases as you move down a group. This trend occurs because additional electron shells are added, increasing distance and reducing the pull on electrons.

These trends help predict how elements might interact or the type of bonds they might form, such as ionic or covalent bonds, by examining their relative electronegativities.

Chemical Properties

Chemical properties are characteristics that dictate how an element interacts with other substances. Electronegativity is a fundamental aspect influencing these properties, as it determines the nature of bonds.

• High Electronegativity: Elements like chlorine, which have high electronegativity, tend to form ionic bonds with metals or covalent bonds with other nonmetals.
• Low Electronegativity: Elements like potassium and sodium, with low electronegativity, are more likely to lose electrons and form positive ions in reactions.

The chemical behavior of elements, such as reactivity and ability to form compounds, hinges on these properties, providing insights into their role in various chemical processes and applications.