Question

What is meant by a chemical bond? Why do atoms form bonds with each other? Why do some elements exist as molecules in nature instead of as free atoms?

Short answer

A chemical bond is the attractive force that holds atoms together in a molecule or an ionic compound due to the sharing or transfer of electrons. Atoms form bonds to achieve a stable configuration called the octet rule, where their outermost electron shell has 8 electrons. Chemical bonds include covalent, ionic, and metallic bonds. Some elements, like hydrogen, oxygen, and nitrogen, exist as molecules in nature instead of free atoms because forming molecular structures, such as diatomic molecules, provides a more stable configuration and satisfies the octet rule.

Step-by-step solution

Define a chemical bond

A chemical bond is the attractive force that holds atoms together in a molecule or an ionic compound due to the sharing or transfer of electrons. Chemical bonds enable the formation of molecules and compounds, which are essential for various chemical reactions.

Reason for the formation of chemical bonds

Atoms form bonds with each other to achieve a stable configuration by obtaining a complete set of electrons in their outermost electron shell. This is known as the octet rule, which states that atoms (with few exceptions) are most stable when they have 8 electrons in their outermost shell. By forming chemical bonds, atoms can gain, lose, or share electrons to achieve the stable configuration. This eventually lowers their potential energy, making the bonded atoms more stable than individual atoms.

Types of chemical bonds

There are several types of chemical bonds, including: 1. Covalent Bonds: These bonds involve the sharing of electrons between two atoms. For example, a water molecule (H2O) consists of two hydrogen atoms sharing their electrons with an oxygen atom. 2. Ionic Bonds: These bonds involve the transfer of electrons between two atoms, resulting in the formation of ions. For example, table salt (sodium chloride, NaCl) is formed by an ionic bond between sodium (Na) and chlorine (Cl). 3. Metallic Bonds: These bonds are characteristic of metals in which electrons are delocalized and move freely among the positively charged metal ions, creating a "sea of electrons."

Elements existing as molecules in nature

Some elements exist as molecules in nature instead of as free atoms due to their higher stability when forming particular molecular structures. Examples of these elements include hydrogen (H2), oxygen (O2), nitrogen (N2), and the halogens, such as chlorine (Cl2) and fluorine (F2). These elements form diatomic (two-atom) molecules because their electrons are equally shared, leading to a lower energy state and thus a more stable configuration. The formation of these molecules also satisfies the octet rule, contributing to their stability in nature.