Covalent bonds are interactions between two atoms that result from the sharing of electrons. The term "covalent" essentially refers to this sharing process. There are two primary types of covalent bonds: nonpolar covalent bonds and polar covalent bonds. The distinction between these two types arises from differences in the atoms' electronegativities.

Electronegativity is defined as a measure of an atom's attraction to electrons, indicating how strongly an atom pulls on electrons. This property is scaled from 0 to 4, where an electronegativity of 0 signifies a weak attraction to electrons, while a value closer to 4 indicates a strong attraction. Understanding electronegativity is crucial, as it explains the formation of the two types of covalent bonds.

When examining the periodic table, one can observe that electronegativity values generally increase from left to right and from bottom to top. This trend means that elements on the right side of the table, such as oxygen and fluorine, are more electronegative than those on the left. Notably, oxygen is one of the most electronegative elements, second only to fluorine. This characteristic is particularly significant when discussing molecules like water, which contains one oxygen atom that exerts a strong pull on shared electrons.

In summary, covalent bonds are formed through the sharing of electrons, with the nature of this sharing influenced by the electronegativity of the involved atoms. Understanding these concepts lays the groundwork for further exploration of nonpolar and polar covalent bonds in future discussions.