Question

Arrange the following bonds from the least polar to the most polar bond: $$ \mathrm{C}-\mathrm{F}, \mathrm{Na}-\mathrm{F}, \mathrm{Ga}-\mathrm{F}, \mathrm{Si}-\mathrm{F} $$

Short answer

The bonds can be ordered from least polar to the most polar as: \(C-F\) (\(\Delta EN = 1.43\)) < \(Si-F\) (\(\Delta EN = 2.08\)) < \(Ga-F\) (\(\Delta EN = 2.17\)) < \(Na-F\) (\(\Delta EN = 3.05\)).

Step-by-step solution

Identify electronegativity values for elements in the given bonds

To arrange the given bonds according to their polarity, first, we need to identify the electronegativity values of the elements involved. Let's find the electronegativity (EN) values for Carbon (C), Fluorine (F), Sodium (Na), Gallium (Ga), and Silicon (Si) using the Pauling scale: Carbon (C) = 2.55 Fluorine (F) = 3.98 Sodium (Na) = 0.93 Gallium (Ga) = 1.81 Silicon (Si) = 1.90

Calculate the electronegativity differences for each bond

Now that we have electronegativity values for each element, we can calculate the electronegativity difference for each bond: C-F: \(\Delta EN = |3.98-2.55| = 1.43\) Na-F: \(\Delta EN = |3.98-0.93| = 3.05\) Ga-F: \(\Delta EN = |3.98-1.81| = 2.17\) Si-F: \(\Delta EN = |3.98-1.90| = 2.08\)

Arrange the bonds from least polar to the most polar

Now that we have the electronegativity differences for each bond, we can easily arrange them from least polar to the most polar: C-F: \(\Delta EN = 1.43\) Ga-F: \(\Delta EN = 2.17\) Si-F: \(\Delta EN = 2.08\) Na-F: \(\Delta EN = 3.05\) By comparing the electronegativity differences, the bonds can be ordered from least polar to the most polar as: C-F < Si-F < Ga-F < Na-F

Key concepts

Electronegativity

Electronegativity is a fundamental concept in chemistry that describes the tendency of an atom to attract electrons towards itself when it forms a chemical bond. Think of it as a measure of how 'greedy' an atom is for electrons. Higher electronegativity means that an atom pulls electrons more strongly.

When two atoms with different electronegativities form a bond, the more electronegative atom will attract the shared electrons closer to itself. This unequal distribution of electrons leads to a partial charge, with the more electronegative atom gaining a slight negative charge and the other atom obtaining a slight positive charge. The ability to predict the behavior of atoms during chemical reactions relies heavily on understanding these electronegativity differences.

Pauling Scale

The Pauling scale, named after the chemist Linus Pauling, is a way of assigning a numerical value to the electronegativity of an element. It's like a leaderboard where elements are ranked based on how strongly they attract electrons in a bond. The scale typically ranges from around 0.7 to 4.0.

Fluorine sits at the top of the scale with a value of 3.98, making it the most electronegative element. In contrast, elements like cesium and francium have very low electronegativity values. This scale is invaluable for predicting the type and polarity of bonds between different atoms, helping students to visualize and understand the chemical landscape.

Polarity of Bonds

The polarity of bonds is all about how electrons are shared between atoms. A nonpolar bond occurs when electrons are shared equally, typical in bonds between atoms of the same element or between elements that have similar electronegativity values. On the other hand, a polar bond is formed when there's an unequal sharing of electrons due to a significant difference in electronegativity between the bonded atoms.

Polar bonds lead to the creation of dipoles, with one end of the bond being more negative and the other more positive. Knowing the polarity of a bond is crucial for understanding the physical properties of molecules, like their boiling and melting points, solubility in various solvents, and even how they interact with light.

Arranging Chemical Bonds

Arranging chemical bonds by their polarity is an essential skill in chemistry. By comparing the electronegativity differences, we can predict how polar a bond is; the greater the difference, the more polar the bond. In the exercise example, we arranged bonds in order of increasing polarity by calculating the electronegativity differences between the bonded atoms using the Pauling scale.

This not only deepens the understanding of chemical bond characteristics but also provides insight into the structure and reactivity of molecules. When arranging bonds, always remember that the greater the difference in electronegativity, the more polar the bond will be—a vital rule for predicting molecular interactions.