Problem 139 - A Complete Resource Book in Chemistry for JEE Main

Question

How many of these elements are less electronegative than N-atom (No. only) \(\mathrm{F}, \mathrm{O}, \mathrm{C}, \mathrm{B}, \mathrm{Be}, \mathrm{P}, \mathrm{C}, \mathrm{Si}, \mathrm{Br}\)

Step-by-Step Solution

Answer

6 elements

Step 1: Determine Electronegativity of Nitrogen

The electronegativity of nitrogen is 3.04 on the Pauling scale.

Step 2: Find Electronegativity of Given Elements

The electronegativity values for the given elements are: - Fluorine (F): 3.98 - Oxygen (O): 3.44 - Carbon (C): 2.55 - Boron (B): 2.04 - Beryllium (Be): 1.57 - Phosphorus (P): 2.19 - Silicon (Si): 1.90 - Bromine (Br): 2.96

Step 3: Compare Each Element with Nitrogen

Compare the electronegativity of each element with nitrogen (3.04): - F (3.98) > N, O (3.44) > N - C (2.55) < N, B (2.04) < N, Be (1.57) < N - P (2.19) < N, Si (1.90) < N, Br (2.96) < N

Step 4: Count Elements Less Electronegative Than Nitrogen

Count the number of elements whose electronegativity is lower than nitrogen's: - C, B, Be, P, Si, Br Six elements are less electronegative than nitrogen.

Key Concepts

Pauling scale

The Pauling scale is a tool used to measure the electronegativity of different elements, which reflects an atom’s ability to attract and hold onto electrons. Developed by Linus Pauling, this scale is perhaps the most commonly used method in chemistry to compare electronegativity across elements.
It ranges from around 0.7 to 4.0, where a higher value indicates a stronger pull on electrons within a chemical bond.

This measure helps predict how atoms will interact, and from this, we can infer certain chemical properties and behaviors. For example, if one element in a compound is significantly more electronegative than the other, it's likely to pull electrons closer, leading to a polar bond formation.

Periodic table elements

The periodic table arranges all known elements in order of increasing atomic number. It is a fundamental tool in chemistry for understanding how elements behave and interact with each other.

In the periodic table, electronegativity values increase across a period (from left to right) and decrease down a group (from top to bottom). This pattern helps predict how different elements will react with each other.

• Fluorine, located at the top right corner, has the highest electronegativity.
• Elements like beryllium and boron, which are further left, have lower electronegativities.

Understanding the placement of elements helps in anticipating their chemical reactivity and types of bonds they can form.

Chemical properties

Chemical properties of elements are largely determined by their electronegativity, affecting how they bond and interact with other elements. Electronegativity plays a crucial role in predicting the type of chemical bonds that will form.

For example, when two atoms with very different electronegativities come together, the bond tends to be ionic, with the more electronegative atom pulling electrons away from the other. Conversely, atoms with similar electronegativities are more likely to share electrons, forming covalent bonds.

• Fluorine and oxygen form polar covalent bonds with many elements due to their high electronegativity.
• Elements like carbon, which has moderate electronegativity, can form versatile bonds, both covalent and polar.

This understanding helps predict how substances will react during chemical processes, an essential aspect of chemistry and chemical engineering.

Nitrogen electronegativity

Nitrogen is a key element in the periodic table with an electronegativity of 3.04 on the Pauling scale. This value positions nitrogen as highly electronegative, though not as high as fluorine or oxygen.

Nitrogen's high electronegativity allows it to form strong covalent bonds, making it a common participant in organic compounds.
In molecules like ammonia (NH₃) and nitrogen gas (N₂), nitrogen’s electronegativity dictates how it interacts and bonds, usually resulting in stable and strong chemical structures.

• Its ability to form triple bonds, such as in N₂, is due to its high electronegativity.
• Nitrogen is essential in biological molecules like DNA and proteins, where it participates in hydrogen bonding and functional group interactions.

Understanding nitrogen's electronegativity is important for various fields, including biochemistry and environmental science, where nitrogen compounds play critical roles.