Question

Determine whether each of the following atoms will form a nonpolar covalent compound or a polar covalent compound, and give the formula of the compound. (a) 2 oxygen (b) hydrogen and bromine (c) oxygen and 2 hydrogen (d) 2 iodine

Short answer

Oxygen (O2) and iodine (I2) form nonpolar covalent compounds. Hydrogen and bromine (HBr), and oxygen with two hydrogens (H2O), form polar covalent compounds.

Step-by-step solution

Analyze Electronegativity Differences - Oxygen

To determine if the compound formed by two oxygen atoms is polar or nonpolar, we need to consider the electronegativity value of oxygen. Since both atoms have the same electronegativity, there is no electronegativity difference, resulting in a nonpolar covalent bond.

Analyze Electronegativity Differences - Hydrogen and Bromine

The difference in electronegativity between hydrogen and bromine will indicate the type of bond. Hydrogen has an electronegativity of 2.2, and bromine has an electronegativity of 2.96. The difference is 0.76, which suggests that a polar covalent bond is more likely.

Analyze Electronegativity Differences - Oxygen and Hydrogen

The difference in electronegativity between oxygen (3.44) and hydrogen (2.2) is 1.24. This significant difference suggests that the bond between oxygen and hydrogen will be polar covalent.

Analyze Electronegativity Differences - Iodine

Two iodine atoms bonding together both have the same electronegativity value. Therefore, just like oxygen, they will form a nonpolar covalent bond since the electronegativity difference is zero.

Write the Formulas for Each Compound

Based on the type of bond, we can write the chemical formulas: (a) Oxygen forms O2 (nonpolar covalent), (b) Hydrogen and bromine form HBr (polar covalent), (c) Oxygen and hydrogen form H2O (polar covalent), (d) Iodine forms I2 (nonpolar covalent).

Key concepts

Electronegativity

To begin with, electronegativity is a measure of an atom’s ability to attract and bind with electrons. It is a crucial concept in chemistry because it helps predict how atoms will bond together to form compounds. Atoms with high electronegativity tend to pull electrons toward themselves, leading to imbalances in the electron distribution when bonded with atoms of lower electronegativity.

Take, for instance, the difference between oxygen and hydrogen. Oxygen has a higher electronegativity (3.44) compared to hydrogen (2.2), which makes bonds between these atoms polar. When identical atoms bond, like two oxygen atoms (each with an electronegativity of 3.44), the electronegativity difference is zero, resulting in a nonpolar bond because the electron distribution is even and balanced.

Polar Covalent Bond

A polar covalent bond is formed when two atoms with different electronegativities come together to share electrons, but not equally. This inequality in sharing leads to a partial negative charge on the more electronegative atom and a partial positive charge on the less electronegative atom.

For example, the bond between hydrogen and bromine (in the compound HBr) is considered polar because bromine has an electronegativity of 2.96 versus hydrogen's 2.2. The electrons are more attracted to bromine, causing a dipole moment where the bromine end of the molecule is slightly negative and the hydrogen end is slightly positive.

Nonpolar Covalent Bond

When atoms with identical or very similar electronegativities bond, they share electrons equally, which results in a nonpolar covalent bond. This type of bond is characterized by an even distribution of electronic charge, leading to no permanent dipole moments within the molecule.

Molecules like O2 and I2 are perfect exemplars of nonpolar covalent compounds. Since both the oxygen atoms in O2 and the iodine atoms in I2 have identical electronegativities, they share electrons equally, and the overall distribution of charge is balanced, making the bond nonpolar.

Chemical Formulas

Chemical formulas represent the types and numbers of atoms in a molecule. They are essential tools for conveying the composition of compounds. In chemical formulas, the element symbols from the periodic table are used, followed by subscripts indicating the number of atoms of each element present in the molecule.

For instance, the chemical formula for water (H2O) indicates that each molecule consists of two hydrogen atoms and one oxygen atom. Learning how to write and interpret chemical formulas is fundamental to understanding chemical reactions and the properties of compounds, whether they display polar covalent, nonpolar covalent, or ionic characteristics.