Problem 37 - Chemistry: The Central Science

Question

Which of the following statements about electronegativity is false? (a) Electronegativity is the ability of an atom in a molecule to attract electron density toward itself. (b) Electronegativity is the same thing as electron affinity. (c) The numerical values for electronegativity have no units. (d) Fluorine is the most electronegative element. (e) Cesium is the least electronegative element.

Step-by-Step Solution

Answer

The false statement is (b): "Electronegativity is the same thing as electron affinity." While both involve the attraction of electrons, they are not the same thing. Electronegativity is the ability of an atom in a molecule to attract electron density, while electron affinity is the energy change when an electron is added to a neutral atom to form a negatively charged ion.

Step 1: Understanding electronegativity

Electronegativity is a measure of the ability of an atom in a molecule to attract electron density towards itself. It is influenced by factors such as atomic size, electron affinity, and ionization energy. Different elements have different electronegativities, and the Pauling scale is commonly used to assign numerical values to electronegativities.

Step 2: Evaluating statement (a)

Statement (a) says, "Electronegativity is the ability of an atom in a molecule to attract electron density toward itself." This statement is true, as it directly ties in with the definition and concept of electronegativity.

Step 3: Evaluating statement (b)

Statement (b) says, "Electronegativity is the same thing as electron affinity." This statement is false. While electron affinity is a measure of the energy change when an electron is added to a neutral atom to form a negatively charged ion, electronegativity is a measure of the ability of an atom in a molecule to attract electron density. Although they are related in that both involve the attraction of electrons, they are not the same thing.

Step 4: Evaluating statement (c)

Statement (c) says, "The numerical values for electronegativity have no units." This statement is true. Electronegativity values, such as those on the Pauling scale, are dimensionless numbers without any units.

Step 5: Evaluating statement (d)

Statement (d) says, "Fluorine is the most electronegative element." This statement is true. Fluorine has the highest electronegativity value on the Pauling scale, with a value of 3.98.

Step 6: Evaluating statement (e)

Statement (e) says, "Cesium is the least electronegative element." This statement is true. Cesium has the lowest electronegativity value on the Pauling scale, with a value of 0.79.

Step 7: Conclusion

Based on our analysis, the false statement among the given options is statement (b), which claims that electronegativity is the same thing as electron affinity.