Which of the following best describes the type of bonding between chlorine atoms in a molecule of Cl₂? A) Dispersion or London force interactions, B) hydrogen bonding, C) metallic bonding, D) covalent bonding, or E) ionic bonding.
A molecule of Cl₂ is simply two chlorine atoms bonded together. And we want to know which will best describe the bond between these two atoms. Let’s take a look at each of our answer choices to see which one will best describe this bond.
The dispersion or London force occurs because electrons move around within a molecule or an atom. As an extreme example, we can imagine if all of the electrons move to one side of our molecule or atom. Since electrons are negatively charged, the side that has the electrons would have a partial negative charge. And the side that has the nucleus, which contains the positively charged protons, would carry a partial positive charge. This unequal distribution of charge due to our arrangement of electrons as they move around is called an instantaneous dipole. This instantaneous dipole can interact with the molecules or atoms around it, causing them to form dipoles too, which can then become attracted to each other. So the dispersion or London force interactions is an attraction that occurs between molecules or atoms.
While dispersion force interactions would certainly occur between molecules of Cl₂, we’re ultimately looking for something that describes the type of bond between the chlorine atoms within the molecule, not between different molecules of Cl₂. So answer choice A is not the correct answer.
Hydrogen bonding, like the name suggests, is a type of intermolecular force that occurs between hydrogen and really electronegative elements, such as oxygen, nitrogen, or fluorine. In water, for example, oxygen is much more electronegative than hydrogen. So it will pull more on the electrons in the bonds between the oxygen and the hydrogen, causing the oxygen to become partially negatively charged and hydrogen to become partially positively charged.
Since there’s a partial positive charge on the hydrogens and a partial negative charge on the oxygen, the oxygen from one water molecule can be attracted to the hydrogen from another water molecule. Like the dispersion force interactions, hydrogen bonding is describing an attractive force that occurs between neighboring molecules. It doesn’t describe a type of bonding between atoms in a molecule. But either way, Cl₂ doesn’t contain any hydrogen. So answer choice B is not the correct answer.
The next answer choice is metallic bonding. Metals like to give up their electrons. So when you have a lump of metal, it’s common for the electrons to be shared among them. These electrons are free to move around, meaning that they’re delocalized. This sharing of electrons between metal atoms is called metallic bonding. However, chlorine isn’t a metal. It’s a halogen found on the far right of the periodic table. So answer choice C is not the correct answer.
The next answer choice is covalent bonding. Covalent bonding typically occurs between nonmetals. When two atoms form a covalent bond, each atom gives one of their electrons to form the bond. So the electron is shared between the atoms participating in the bond. This perfectly describes the bond between our nonmetal chlorine atoms in a molecule of Cl₂. So answer choice D is the correct answer. But let’s look at answer choice E just so we make sure that we understand it.
Answer choice E is ionic bonding, which generally occurs between a metal and a nonmetal. In an ionic bond, such as the one between sodium and chlorine in sodium chloride, the chlorine is so much more electronegative than the sodium that it essentially takes an electron from sodium, forming positively charged sodium ions and negatively charged chlorine ions. Substances that form ionic bonds like to form lattices composed of alternating negatively and positively charged ions. A molecule of Cl₂ is just two chlorine atoms, which are both nonmetals. So they would not form an ionic bond. So answer choice E is not correct.
So, like we’ve already determined, the covalent bond is the best way to describe the type of bonding between chlorine atoms in a molecule of Cl₂.