Summary
Highlights
A recap of ions as atoms that have lost or gained electrons to achieve stability, represented with equations. For instance, a sodium atom loses one electron to form a Na+ ion, while a chlorine atom gains one electron to form a Cl- ion. These reactions typically involve the transfer of electrons from an atom with excess electrons (like sodium) to an atom needing electrons (like chlorine).
After electron transfer, both atoms become ions with full outer shells, represented with square brackets and their charge. The opposite charges of these ions lead to strong electrostatic attraction, forming an ionic compound. This strong attractive force is called an ionic bond, comparable in strength to covalent bonds.
Dot and cross diagrams are used to illustrate ionic compound formation. Key features include using dots for electrons from one atom and crosses for electrons from another to distinguish them, and arrows to show electron movement. Diagrams can show all electron shells or only the outermost shells, depending on the requirement.
A more complex example is the formation of magnesium chloride. Magnesium has two outer electrons to lose, while each of the two chlorine atoms needs one electron. Magnesium transfers one electron to each chlorine atom, resulting in a Mg2+ ion and two Cl- ions. In diagrams with multiple ions, they are arranged as they would be in a real compound, with the negatively charged chlorides positioned around the positive magnesium.