Single-valent

In chemistry, 'single-valent' describes an atom or ion that has a valence of one. Valence refers to the combining power of an atom, or the number of chemical bonds an atom can form with other atoms. A single-valent atom can form one covalent bond with another atom, meaning it shares one pair of electrons. Elements that are single-valent commonly form simple compounds and are involved in the formation of various molecules. They exhibit predictable chemical behavior when interacting with other atoms and this stability makes them fundamental in many chemical reactions and compounds. Understanding the concept of single-valency is therefore essential for predicting how atoms will interact with one another.

Single-valent meaning with examples

• Sodium (Na) is a single-valent element, readily forming one bond. It combines with chlorine to produce sodium chloride (NaCl). This single-valent nature makes sodium's chemistry highly predictable in various reactions such as reacting with water to release hydrogen gas. Sodium's behavior is critical in industrial and laboratory contexts, highlighting its single-valency as a key concept.
• Hydrogen (H), often considered the simplest single-valent element, forms bonds with a wide array of elements. Hydrogen bonds are essential in both organic and inorganic compounds. Its single valence allows it to form molecules like HCl or water (H₂O) along with larger molecules.
• The halides, such as fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), are examples of single-valent atoms. These elements readily form bonds and compounds, such as HCl, due to their single valence and high electronegativity, which makes them very reactive, and they are instrumental in various industrial processes.
• In an ionic context, the sodium ion (Na⁺) exhibits single-valency. This means it will form an ionic bond with just one chloride ion, such as in NaCl. This single-valent nature is critical in explaining the structure of these ionic compounds.
• Atoms of the elements in Group 7 (formerly VIIA) of the periodic table, also known as the halogens, are single-valent, exhibiting one valence electron and forming single covalent bonds with other atoms. These characteristics make them highly reactive and essential for many synthetic processes.