Bonding Across the Periodic Table

Some atoms easily lose their valence electrons in order to gain an electron configuration, which is stable. This is characteristic of atoms with low electron affinity. Ionization energy of these atoms is low and consequently they require less energy to ionize. When this happens, these atoms become positively charged ions or cations. The electrons lost are gained by atoms with high electronegativities, which become negatively charged ions or anions. Due to the difference in charge, the two sets of ions attract each other electrostatically. This is called ionic bonding (Zumdahl & Zumdahl, 2007, p.346).

On the left side of the periodic table, atoms gain stability by formation of ions. This is far easier than for these atoms to gain electrons. They are therefore said to have low electronegativity. When they lose their valence electrons, they gain a net positive charge because they posses more protons relative to the electrons. The charge carried by these cations depends on the number of electrons lost. For examples, metals in group 1 will carry a net charge of positive one and those in two a charge of positive two (Zumdahl & Zumdahl, 2007, p.346).

Elements on the right side of the periodic table have high electron affinity and therefore tend to gain electrons from the surrounding so as to obtain a stable configuration. In the process, they obtain a negative charge creating an anion. Electron affinity increases as one moves to the right across the periodic table.

Bonding is facilitated by the difference in charge between the two species of ions. These are brought together by electrostatic force to create a strong bond. The number of atoms coming together depends on charges borne by each ion. For example, one sodium cation will bond with one chloride ion to form sodium chloride molecule, which is represented as Na⁺Cl^–. Similarly, a magnesium ion will couple with two nitrate ions to form magnesium nitrate, Mg (NO₂)₂.