4. What type of intermolecular force is found between:
a. F2
b. Cl2
c. water molecules?
a. F2: F2 molecules are held together by London dispersion forces, which are temporary attractive forces caused by the movement of electrons. In F2, the electron cloud is not evenly distributed around each atom, leading to temporary dipoles that induce dipoles in neighboring molecules.
b. Cl2: Similar to F2, Cl2 molecules are also held together by London dispersion forces. The larger the atoms, the larger the electron cloud, resulting in stronger London dispersion forces.
c. Water molecules: Water molecules are held together by hydrogen bonding. Hydrogen bonding is a type of intermolecular force that occurs when a hydrogen atom is covalently bonded to an electronegative atom (such as oxygen or nitrogen) and is attracted to another electronegative atom in a neighboring molecule. In water, the positive hydrogen atoms are attracted to the negative oxygen atoms of neighboring water molecules, forming relatively strong hydrogen bonds.
a. For F2 molecules, the intermolecular force is a London dispersion force or Van der Waals force. This force is caused by temporary fluctuations in electron distribution, resulting in temporary dipoles that induce dipoles in neighboring molecules.
b. Similarly, for Cl2 molecules, the dominant intermolecular force is also London dispersion force or Van der Waals force. This is because Cl2 is a nonpolar molecule, and like F2, it experiences temporary fluctuations in electron distribution, leading to temporary dipoles.
c. For water molecules (H2O), the intermolecular force is hydrogen bonding. This is a special type of dipole-dipole interaction. It occurs due to the highly electronegative oxygen atom in a water molecule attracting the hydrogen atoms of neighboring water molecules. The hydrogen bonding is responsible for many unique properties of water, such as its high boiling point and surface tension.
To determine the type of intermolecular force between molecules, we need to consider the polarity of the molecules and the types of bonds present.
a. F2: Fluorine (F) is a highly electronegative element. Since F2 consists of two identical fluorine atoms, the molecule is nonpolar, meaning it has no permanent dipole moment. Therefore, the main intermolecular force between F2 molecules is London dispersion forces, also known as induced dipole- induced dipole interactions. These forces arise from temporary fluctuations in electron distribution, resulting in an instantaneous dipole, which induces a dipole in neighboring molecules.
b. Cl2: Chlorine (Cl) is also a highly electronegative element. Like F2, Cl2 is a nonpolar molecule since it consists of two identical chlorine atoms. Therefore, the main intermolecular force between Cl2 molecules is also London dispersion forces.
c. Water (H2O) molecules: Water is a polar molecule because of its bent molecular shape and the difference in electronegativity between hydrogen (H) and oxygen (O). The oxygen atom in water is more electronegative, giving it a partial negative charge, while the hydrogen atoms have a partial positive charge. The intermolecular forces between water molecules are hydrogen bonds. Hydrogen bonds are stronger than London dispersion forces and are formed between the partially positive hydrogen atom of one water molecule and the partially negative oxygen atom of another water molecule.
In summary:
a. F2: London dispersion forces
b. Cl2: London dispersion forces
c. Water molecules: Hydrogen bonds