Question

What holds the atoms together in a crystal of magnesium chloride (MgCl₂)?

Short answer

In MgCl₂, the electrostatic force of attraction between the oppositely charged ions (Mg⁺ and Cl^-) holds the atoms together through ionic bonds.

Step-by-step solution

Electronic configuration of magnesium and chloride

MgCl₂ is composed of Mg⁺ and Cl^-.

Magnesium has 12 electrons, resulting in an electrical configuration of 2, 8, 2. Thus, magnesium has two electrons in its valence shell. Each chlorine atom in MgCl₂ contains 17 electrons, and its electrical configuration is 2, 8, 7. As a result, each chlorine atom has seven valence electrons.

Formation of ionic bond

An ionic bond is a type of bond that is formed due to the electrostatic attraction between a positive and a negatively charged ion in a chemical compound. When one atom in a compound transfers electrons from itself to a neighboring atom, the result is an electrovalent or ionic compound.

Formation of MgCl2

Mgmust give away two valence electrons to complete its octet due to two electrons in the valence shell. Since it possesses seven electrons in its valence shell, each chlorine atom seeks to complete its octet by adding one more electron to its outermost orbit.

Thus, Mg transfers two electrons to two Cl atoms, giving a +2 charge on Mg and each chlorine atom a -1 charge, resulting in the formation of ionic bonds between the atoms of the molecule.