Question

Predict which bond is the most polar. $$ \begin{array}{ll}{\text { a. } C-O} & {\text { c. } C-C l} \\ {\text { b. } S i-O} & {\text { d. } C-B r}\end{array} $$

Short answer

The most polar bond among the given options is the \(Si-O\) bond, with an electronegativity difference of 1.54.

Step-by-step solution

Determine the electronegativity values of the atoms involved

First, consult a periodic table (or a reference table of electronegativity values) to find the electronegativity values of the different atoms involved in the bonds. The relevant atoms are C (carbon), O (oxygen), Si (silicon), Cl (chlorine), and Br (bromine). The electronegativity values are: - Carbon (C): 2.55 - Oxygen (O): 3.44 - Silicon (Si): 1.90 - Chlorine (Cl): 3.16 - Bromine (Br): 2.96

Calculate the electronegativity differences for each bond

Calculate the difference in electronegativity for each bond using the following formula: Electronegativity difference = | Electronegativity of atom 1 - Electronegativity of atom 2 | For each bond: a. C-O: Electronegativity difference = |2.55 - 3.44| = 0.89 b. Si-O: Electronegativity difference = |1.90 - 3.44| = 1.54 c. C-Cl: Electronegativity difference = |2.55 - 3.16| = 0.61 d. C-Br: Electronegativity difference = |2.55 - 2.96| = 0.41

Compare the electronegativity differences and identify the most polar bond

Now, we will compare the electronegativity differences of each bond: - C-O: 0.89 - Si-O: 1.54 - C-Cl: 0.61 - C-Br: 0.41 The bond with the largest electronegativity difference is the Si-O bond, with an electronegativity difference of 1.54. The greater the electronegativity difference, the more polar the bond. Therefore, the most polar bond among the given options is the \(Si-O\) bond.

Key concepts

Polar Bond

When we talk about polar bonds, we're talking about a type of chemical bond where electrons are not shared equally between two atoms. This happens because one atom is more electronegative than the other, causing it to attract the shared electrons more strongly. Imagine a tug-of-war but with electrons in between two atoms; the atom with higher electronegativity wins and pulls the electrons closer.

In molecules like water (H₂O), the oxygen atom is more electronegative than the hydrogen atoms. This makes the oxygen end of the molecule slightly negative and the hydrogen ends slightly positive, resulting in a polar molecule. Polar bonds are crucial because they can influence the properties of the molecule, including its boiling and melting points.

Chemical Bonding

Chemical bonding is the joining of atoms to form molecules and compounds, which are the building blocks of matter. There are several types of chemical bonds, but the primary ones are ionic bonds, covalent bonds, and metallic bonds:

• Ionic Bonds: Formed when one atom donates an electron to another atom, creating a bond between a positively charged ion and a negatively charged ion.
• Covalent Bonds: Occur when two atoms share one or more pairs of electrons, which can be either polar or nonpolar depending on the electronegativity difference between the atoms.
• Metallic Bonds: Result from the attraction between free-floating electrons and the positively charged metal ions.

Chemical bonds determine the physical and chemical properties of a substance, such as its phase at room temperature, solubility, and electrical conductivity.

Periodic Table

The periodic table is an organized chart of chemical elements, designed to provide a framework for understanding chemical behavior and properties. Developed by Dmitri Mendeleev and later refined, it categorizes elements based on atomic number, electron configuration, and recurring chemical properties.

Elements are arranged in rows called periods and columns known as groups. Elements in the same group have similar chemical properties. For example, all the elements in Group 17, known as halogens, tend to form salts when combined with metals.

The periodic table is crucial when determining electronegativity and bonding types. Elements on the top right, such as fluorine and oxygen, are generally more electronegative, making them key players in forming polar bonds.

Electronegativity Difference

Electronegativity is a measure of an atom's ability to attract shared electrons in a bond. When comparing two atoms, the difference in their electronegativity values can tell us a lot about the type of bond they will form. Calculating the electronegativity difference involves simply subtracting the smaller value from the larger one.

If the difference is:

• 0 to 0.4: The bond is generally considered nonpolar covalent, where electrons are shared almost equally.
• 0.5 to 1.7: The bond becomes polar covalent, indicating unequal sharing of electrons.
• 1.8 or more: The bond is typically ionic, where one atom completely transfers its electrons to the other.

Understanding electronegativity differences helps predict the behavior and interaction of molecules, which is essential in many fields, including chemistry and biology.