A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds. A chemical element bonded to an identical chemical element is not a chemical compound since only one element, not two different elements, is involved.
There are four types of compounds, depending on how the constituent atoms are held together:
molecules held together by covalent bondsionic compounds held together by ionic bondsintermetallic compounds held together by metallic bondscertain complexes held together by coordinate covalent bonds.
A chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, using the standard abbreviations for the chemical elements, and subscripts to indicate the number of atoms involved. For example, water is composed of two hydrogen atoms bonded to one oxygenatom: the chemical formula is H2O. Many chemical compounds have a unique numerical identifier assigned by the Chemical Abstracts Service (CAS): its CAS number.
A compound can be converted to a different chemical composition by interaction with a second chemical compound via a chemical reaction. In this process, bonds between atoms are broken in both of the interacting compounds, and then bonds are reformed so that new associations are made between atoms.

What is a Chemical Compound?

A chemical compound is a substance made up of two or more different elements that are chemically bonded together. These elements are combined in specific ratios and held together by chemical bonds, resulting in a unique and distinct substance with its own set of properties.

Elements and Atoms

Elements are the fundamental building blocks of matter. They are represented by symbols on the periodic table, such as H for hydrogen, O for oxygen, and C for carbon. Each element consists of tiny particles called atoms. Atoms are the smallest units of an element that retain its chemical properties.

Chemical Bonds

Chemical bonds are forces that hold atoms together in compounds. There are three main types of chemical bonds:

1. Ionic Bonds: Ionic bonds occur when one or more electrons are transferred from one atom to another, resulting in the formation of ions. These ions, which have a positive or negative charge, are attracted to each other and form a compound. For example, sodium chloride (NaCl) is formed by the transfer of an electron from sodium to chlorine.

2. Covalent Bonds: Covalent bonds occur when atoms share one or more pairs of electrons. This type of bond is typically formed between nonmetal elements. For instance, in water (H2O), the oxygen atom shares electrons with two hydrogen atoms.

3. Metallic Bonds: Metallic bonds occur in metals when the outermost electrons of the atoms are delocalized and shared among all the atoms. This sharing creates a "sea" of electrons that hold the metal atoms together. Metallic bonds give metals their unique properties, such as malleability and conductivity.

Molecular and Ionic Compounds

Chemical compounds can be classified into two main types: molecular compounds and ionic compounds.

1. Molecular Compounds: Molecular compounds are formed through covalent bonds. They consist of discrete molecules made up of atoms bonded together. Examples include carbon dioxide (CO2), methane (CH4), and glucose (C6H12O6).

2. Ionic Compounds: Ionic compounds are formed through ionic bonds. They consist of positive and negative ions held together by electrostatic forces. Ionic compounds often form crystalline structures and have high melting and boiling points. Examples include sodium chloride (NaCl), calcium carbonate (CaCO3), and magnesium oxide (MgO).

Properties and Uses

Chemical compounds have unique properties that are different from their constituent elements. These properties depend on the types of atoms present, the arrangement of atoms, and the strength of the chemical bonds. Understanding the properties of compounds is essential for various applications, including medicine, materials science, agriculture, and environmental studies.

In Summary

A chemical compound is a substance composed of two or more elements that are chemically bonded together. These compounds can be either molecular or ionic, depending on the type of bonds formed. The properties of compounds differ from their constituent elements, making them important in numerous fields of science and technology.