Problem 10 - Chemistry An Atoms First Approach

Question

Give one example of a compound having a linear molecular structure that has an overall dipole moment (is polar) and one example that does not have an overall dipole moment (is nonpolar). Do the same for molecules that have trigonal planar and tetrahedral molecular structures.

Step-by-Step Solution

Answer

Examples of compounds with different molecular geometries: 1. Linear molecular structure - Polar: Hydrogen chloride (HCl) - Nonpolar: Carbon dioxide (CO2) 2. Trigonal planar molecular structure - Polar: Sulfur trioxide (SO3) - Nonpolar: Boron trifluoride (BF3) 3. Tetrahedral molecular structure - Polar: Methane (CH4) - Nonpolar: Carbon tetrachloride (CCl4)

Step 1: Linear molecular structure - Polar

An example of a linear molecular structure that has an overall dipole moment (polar) is hydrogen chloride (HCl). In HCl, there is a difference in electronegativity between the hydrogen and chlorine atoms, leading to an uneven distribution of electron density and the creation of a dipole moment, making it polar.

Step 2: Linear molecular structure - Nonpolar

An example of a linear molecular structure that does not have an overall dipole moment (nonpolar) is carbon dioxide (CO2). In CO2, the oxygen atoms are more electronegative than the central carbon atom, but since the molecule is linear and the more electronegative atoms are symmetrically arranged, these dipoles cancel each other out and it is a nonpolar molecule.

Step 3: Trigonal planar molecular structure - Polar

An example of a trigonal planar molecular structure with an overall dipole moment (polar) is sulfur trioxide (SO3). This molecule has a trigonal planar geometry, with sulfur in the center and oxygen atoms surrounding it in a triangle. Due to the difference in electronegativity between the sulfur and oxygen atoms, there is an overall dipole moment, and the molecule is polar.

Step 4: Trigonal planar molecular structure - Nonpolar

An example of a trigonal planar molecular structure without an overall dipole moment (nonpolar) is boron trifluoride (BF3). In this molecule, boron is the central atom and is surrounded by three fluorine atoms in a trigonal planar arrangement. Although the fluorine atoms have greater electronegativity than boron, the dipoles created by these differences cancel each other out due to the molecule's symmetry, making it nonpolar.

Step 5: Tetrahedral molecular structure - Polar

An example of a tetrahedral molecular structure with an overall dipole moment (polar) is methane (CH4). In this molecule, carbon is the central atom and is surrounded by four hydrogen atoms in a tetrahedral configuration. The difference in electronegativity between carbon and hydrogen creates a dipole moment, and the overall geometry results in a polar molecule.

Step 6: Tetrahedral molecular structure - Nonpolar

An example of a tetrahedral molecular structure without an overall dipole moment (nonpolar) is carbon tetrachloride (CCl4). In CCl4, carbon is the central atom and is surrounded by four chlorine atoms in a tetrahedral arrangement. Although chlorine atoms are more electronegative than carbon, the symmetric distribution of the chlorine atoms results in the cancellation of the individual dipoles, making this molecule nonpolar.