Electronegativity is a measure of the ability of an atom to attract electrons to itself. The higher the electronegativity of an atom, the more it will pull electrons away from other atoms. The determination of electronegativity of an element is done by measuring the electron affinity of an atom. In other words, Electronegativity is a fundamental concept in the world of chemistry, a guiding principle that governs the interactions between atoms and molecules. It’s the reason why some elements are more likely to bond with others, and why certain compounds display distinctive properties.
In this article, we’ll learn in detail about electronegativity, exploring its definition, significance, and impact on the behavior of specific elements.
What is Electronegativity?
Electronegativity is the ability of an atom in a chemical compound to attract a bond pair of electrons towards itself. The electronegativity of any given element is not constant. It helps us understand the distribution of electrons in molecules and predict how atoms will bond with each other. On the periodic table, electronegativity generally increases as you move from left to right across a period and decreases as you move down a group. Electronegativity is crucial for explaining a wide range of chemical phenomena.
Electronegativity Definition
Electronegativity is defined in chemistry as a measure of an atom’s ability to attract shared electrons to itself.
Electronegativity is measured on various scales, with the Pauling scale being the most widely used.
Electronegativity Meaning
Electronegativity indicates the net result of the tendencies of atoms in different elements to attract the bond-forming electron pairs. We measure electronegativity on several scales. The most commonly used scale was designed by Linus Pauling. Electronegativity values provide insights into the polarity of chemical bonds. Atoms with higher electronegativity tend to attract electrons more strongly, leading to an unequal sharing of electrons in a covalent bond. This results in a partial negative charge on the more electronegative atom and a partial positive charge on the less electronegative atom.
An American chemist named Linus Pauling in the year 1932 developed the most accurate scale of electronegativity. His scale popularly referred to as Pauling scale was mainly based on the development of Valence Bond Theory which seemingly helped him understand the relationship between one chemical property with another property. The scale was further based on bond-energy calculations of different elements having covalent bonds. However, electronegativity of an element cannot be measured directly as it depends solely on the different properties of each element.
Electronegativity Table of Elements
Electronegativity varies in a predictable way across the periodic table. On the periodic table, electronegativity generally increases as you move from left to right across a period and decreases as you move down a group.
The electronegativity of each element can be found on the periodic table. There are also some electronegativity trends that can be observed in the Periodic table. On moving from left to right in the Periodic table, electronegativity increases whereas on moving from top to bottom, the electronegativity decreases.
Electronegativity Chart
The electronegativity chart can also be created in accordance with the periodic table. The chart is given below and it is much easier to find the electronegativity values of the elements. The values are arranged as per the number of the element in the periodic table.A chart or graph of electronegativity values can help visualize the trends across the periodic table. Elements on the left side of the periodic table have lower electronegativity values, while those on the right have higher values.
Electronegativity Trend in the Periodic Table
In the period table from left to right across electronegativity increases. This is because of the increased number of protons as the atomic number increase. From top to bottom electronegativity decreases because of the increasing size of the atoms. As a result, Fluorine is considered the most electronegative element while cesium is the least electronegative element. Halogens are considered to have a high electronegativity, while it is low for the alkali metals and alkaline earth metals. The trend of increasing electronegativity across a period is primarily due to the increasing number of protons in the nucleus, which leads to a stronger attraction for electrons. As you move from left to right across a period, the atomic number increases, and so does the electronegativity.
Electronegativity of Specific Elements
Now, let’s explore the electronegativity of specific elements . Here is a table listing the electronegativity values of specific elements in order of increasing atomic number according to the Pauling scale.
Electronegativity of Hydrogen (H)
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2.20
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Electronegativity of Helium (He)
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N/A (Noble Gas)
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Electronegativity of Lithium (Li)
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0.98
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Electronegativity of Beryllium (Be)
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1.57
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Electronegativity of Boron (B)
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2.04
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Electronegativity of Carbon (C)
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2.55
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Electronegativity of Nitrogen (N)
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3.04
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Electronegativity of Oxygen (O)
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3.44
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Electronegativity of Fluorine (F)
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3.98
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Electronegativity of Neon (Ne)
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N/A (Noble Gas)
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Electronegativity of Sodium (Na)
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0.93
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Electronegativity of Magnesium (Mg)
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1.31
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Electronegativity of Bromine
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3.0
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Electronegativity of Phosphorus (P)
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2.19
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Electronegativity of Sulfur (S)
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2.58
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Electronegativity of Chlorine (Cl)
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3.16
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Electronegativity of Iodine
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2.66
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Element with Highest Electronegativity
Fluorine is the most electronegative element, while francium is one of the least electronegative. Fluorine holds the distinction of having the highest electronegativity of any element. Its value of 4.0 on the Pauling scale makes it the most effective electron attractor.
Least Electronegative Elements
Cesium and Francium are least Electronegative elements. Cesium and Fracium has electronegativity value of 0.69 and 0.7 on pauling scale, respectively.
Differences in Electronegativity Across Elements
The differences in electronegativity values between atoms in a chemical bond can be used to classify the type of bond formed. Larger differences result in ionic bonds, while smaller differences lead to polar covalent bonds.
How to Calculate Electronegativity?
Electronegativity depends upon the force of attraction between the nucleus and bonding electrons in the outer shell. Electronegativity of any given element is not constant. It varies according to the element to which it is bound. It is not a measurable quantity. It is only a relative number.
Electronegativity of an element is determined through Mulliken scale, and electronegativity difference of two elements is calculated through polling scale. Allred Roschow’s scale is also used to calculate the electronegativity of an atom.
Pauling Scale of Electronegativity
The Pauling scale is commonly used to calculate electronegativity. It assigns values to elements based on their chemical behavior and the properties of their compounds. The electronegativity of an element is determined by factors such as ionization energy and electron affinity.
Electronegativity Series
An electronegativity series is often referred to as an electronegativity chart, lists elements in order of their electronegativity values. The electronegativity of an element is a measure of its ability to attract electrons in a chemical bond, and it plays a crucial role in understanding the nature of chemical bonds and the behavior of elements in compounds. The Pauling scale is one of the most commonly used scales for measuring electronegativity.
Electronegativity Order
The order of electronegativity of some common elements is,
H <P < C < I < S < Br < Cl < O < F
Electronegativity Vs Electron Affinity
Electronegativity refers to the ability of the atoms to attract electrons from the other elements. Electron affinity refers to the amount of energy that is liberated whenever a molecule or a neutral atom tends to acquire an electron from the other elements. Electronegativity and electron affinity are related but distinct concepts. Electron affinity is the energy change associated with adding an electron to an isolated atom, while electronegativity pertains to the ability of an atom to attract electrons in a chemical bond. Electronegativity is a more comprehensive concept that takes into account various atomic properties.
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The ability of an atom to attract electrons in a chemical bond.
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The energy change associated with adding an electron to an isolated atom.
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Electronegativity helps predict the type of chemical bond formed between two atoms (e.g., ionic or covalent)
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Electron affinity contributes to an atom’s reactivity but does not directly predict the type of bond formed.
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Used to understand the behavior of elements in compounds, the polarity of bonds, and the electronegativity trends in the periodic table.
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Often employed to assess an element’s tendency to gain electrons and form negatively charged ions (anions).
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Electronegativity plays a significant role in determining the distribution of electrons in molecules and the nature of chemical reactions.
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Electron affinity is one of several factors influencing the reactivity of elements, especially those involved in redox reactions.
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Note: Fluorine (F) has the highest electronegativity, contributing to the polarity of the HF molecule while Chlorine (Cl) has a high electron affinity, as the addition of an electron releases energy.
Factors Affecting Electronegativity
Electronegativity of an atom is affected by following factors:
Atomic Radius
Larger the atomic radius means larger the atomic size and hence decrease in the electronegativity of the atom
Nuclear Charge
Nuclear Charge is directly proportional to the number of protons. Larger the number of protons, more will be the electronegativity of the atom
Screening Effect
Screening Effect is due to the presence of inner electrons which shield the outer electrons from nuclear effect. Hence larger the screening effect less will be the electronegativity
Also, Check
Sample Questions on Electronegativity
Q1. Which element has the highest electronegativity on the Pauling scale?
Answer:
Fluorine (F) has the highest electronegativity on the Pauling scale. It has an electronegativity value of 4.0, making it the most effective electron attractor among all the elements. This high electronegativity is due to fluorine’s strong attraction for electrons, which leads to the formation of highly polar covalent bonds in compounds it participates in.
Q2. Why does electronegativity increase across a period in the periodic table?
Answer:
Electronegativity increases across a period in the periodic table primarily because of the increasing number of protons in the nucleus. As you move from left to right across a period, the atomic number (the number of protons) increases. This higher positive charge in the nucleus exerts a stronger pull on the electrons in the outermost energy level, resulting in a greater ability to attract electrons. Consequently, elements on the right side of the periodic table have higher electronegativity values, while those on the left have lower values.
Q3. Give an example of a compound with a polar covalent bond and state the reason for its polarity.
Answer:
One common example of a compound with a polar covalent bond is water (H2O). The polarity of the H2O molecule arises from the difference in electronegativity between the hydrogen (H) and oxygen (O) atoms.
Q4. How does electronegativity influence the type of bond formed between two atoms?
Answer:
Electronegativity influences the type of bond formed. If the electronegativity difference is small, a nonpolar covalent bond is likely. A larger difference leads to a polar covalent bond or, in extreme cases, an ionic bond.
Q5. How differences in electronegativity lead to the development of partial charges.
Answer:
In water (H2O), the electronegativity difference between hydrogen and oxygen leads to partial positive charges on hydrogen and a partial negative charge on oxygen.
Q6. What is the impact of electronegativity on the physical properties of substances?
Answer:
Electronegativity affects physical properties such as melting and boiling points, solubility, and conductivity. Substances with higher electronegativity differences tend to have higher melting and boiling points and may exhibit better solubility in polar solvents.
Q7. Elaborate on the concept of Pauling electronegativity and its applications in predicting bond polarity.
Answer:
Pauling electronegativity is a scale measuring the electronegativity of elements. The difference in Pauling electronegativity values between two atoms can be used to predict the polarity of a bond: nonpolar for small differences, polar covalent for moderate differences, and ionic for large differences.
Q8. How electronegativity is significant in chemical bonding?
Answer:
Electronegativity is a measure of an atom’s ability to attract and hold electrons in a chemical bond. It is crucial in chemical bonding as it helps predict the direction and type of bond formation between atoms. Higher electronegativity values indicate a stronger attraction for electrons.
Q9. Compare the electronegativities of chlorine and oxygen, providing reasons for any observed differences.
Answer:
Oxygen has a higher electronegativity than chlorine. This is because electronegativity generally increases across a period in the periodic table, and oxygen is to the right of chlorine. Additionally, oxygen’s smaller atomic size contributes to its higher electronegativity.
Q10. Describe the trend of electronegativity across a period in the periodic table and explain the underlying factors.
Answer:
Electronegativity generally increases across a period from left to right in the periodic table. This trend is attributed to the increasing effective nuclear charge and decreasing atomic size, leading to a stronger attraction for electrons by the atoms.
Q11. Discuss the role of electronegativity in determining the polarity of chemical bonds.
Answer:
Electronegativity difference between two atoms in a bond determines the bond’s polarity. If the electronegativity difference is significant, the bond is polar, with the more electronegative atom acquiring a partial negative charge, and the less electronegative atom acquiring a partial positive charge.
Electronegativity – FAQs
1. Why does Electronegativity Increase across a Period?
Electronegativity increases across a period due to the increasing number of protons in the nucleus. This higher positive charge results in a stronger attraction for electrons, making atoms more electronegative.
2. Why does Electronegativity decrease down a Group?
Electronegativity decreases down a group because the number of energy levels (shells) increases. As electrons are farther from the nucleus, they experience less attraction, leading to lower electronegativity.
3. How to Find Electronegativity of an Element?
You can find the electronegativity of an element on the periodic table, typically listed using the Pauling scale. Alternatively, you can refer to electronegativity tables or resources that provide these values.
4. What is Polarizability and how it is related to Electronegativity?
Polarizability refers to an atom’s ability to deform its electron cloud in response to an external electric field. It is related to electronegativity in the sense that elements with lower electronegativity values .
5. Why does Fluorine have the Highest Electronegativity among all Elements?
Fluorine has the highest electronegativity because it has a strong attraction for electrons. This is primarily due to its small atomic size and high effective nuclear charge (the number of protons in its nucleus). Fluorine’s ability to attract electrons is the strongest among all the elements.
6. Can Electronegativity values change for the same element under different circumstances?
Electronegativity values are generally considered constant for a specific element. However, in certain chemical environments or compounds, the electronegativity of an element may exhibit slight variations due to factors like oxidation state and the nature of the surrounding atoms.
7. How is Element’s Position in Periodic Table determine their Electronegativity?
The electronegativity of an element is influenced by its position on the periodic table. In general, electronegativity increases as you move from left to right across a period and decreases as you go down a group. Elements in the top right corner of the periodic table, such as fluorine and oxygen, tend to have the highest electronegativity values. Elements on the left and bottom of the periodic table, such as cesium and francium, have lower electronegativity values.
8. How is Electronegativity different from Electron Affinity?
Electronegativity and electron affinity are related but distinct concepts. Electronegativity measures an atom’s ability to attract and hold onto electrons in a chemical bond. On the other hand, electron affinity measures the energy change when an atom gains an electron.
9. What is the Imapct of Electronegativity on Covalent Bonding?
Electronegativity tends to create polar covalent bonding between the atoms. Larger the difference between the electronegativity of the atoms, more will be the polarity and elctron will shift to the more electronegative atom side
10. What is the nature of Bonds Between Highly Electronegative and Highly Electropositive Atoms?
The bond between Highly Electronegative and Highly Electropositive Atoms is ionic in nature
11. Which element has the Lowest Electronegativity?
Cesium and Francium has the lowest Electronegativity
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