Question

Describe the difference between a monatomic ion and a polyatomic ion, and give an example of each

Short answer

The main difference between monatomic and polyatomic ions is their composition. Monatomic ions consist of a single atom with a positive or negative charge, such as the sodium ion (Na\(^+\)). Polyatomic ions consist of two or more atoms covalently bonded together with a net charge, like the nitrate ion (NO\(_3^-\)).

Step-by-step solution

Definition of Monatomic Ions

Monatomic ions are ions that consist of only one atom with a positive or negative charge. This means that the ion has gained or lost one or more electrons, resulting in an imbalance between the number of protons and electrons. These ions are usually formed by transition metals and groups 1, 2, and 13-18 elements in the periodic table.

Definition of Polyatomic Ions

Polyatomic ions are ions that consist of two or more atoms with a net positive or negative charge. These atoms are usually covalently bonded, meaning they share electrons among each other. Some common polyatomic ions are sulfate, nitrate, and phosphate.

Differences Between Monatomic and Polyatomic Ions

The main difference between monatomic and polyatomic ions is their composition. Monatomic ions consist of a single atom, while polyatomic ions consist of two or more atoms covalently bonded together. The net charge in both cases is the result of the overall imbalance of protons and electrons, ensuring that each ion has a net electric charge.

Example of Monatomic Ion

A classic example of a monatomic ion is the sodium ion (Na\(^+\)). The sodium atom loses an electron, leaving it with 11 protons and 10 electrons, resulting in a net +1 charge.

Example of Polyatomic Ion

A well-known example of a polyatomic ion is the nitrate ion (NO\(_3^-\)). It consists of one nitrogen atom and three oxygen atoms covalently bonded together, with a net charge of -1 due to an extra electron shared among all the atoms in the ion.

Key concepts

Ions in Chemistry

In chemistry, understanding the role of ions is fundamental to the study of substances and their reactions. An ion is an atom or molecule that has gained or lost electrons, thus obtaining a net electric charge. This charge can be either positive, in the case of cations, or negative, for anions. The formation of ions is a process driven by an atom's endeavor to reach a more stable, energetically favorable electronic configuration.

Monatomic ions, which are composed of a single atom with a charge, exemplify the simplest form of ions. For instance, when a sodium atom loses an electron, it becomes a sodium ion ((Na^+)). Polyatomic ions, on the other hand, are made up of two or more atoms that are covalently bonded, yet still carry a charge as a whole. The nitrate ion ((NO_3^-)), a group bonding a nitrogen atom with three oxygens, is a typical example of a polyatomic ion. Because ions participate prominently in chemical reactions, mostly as reactants or products, a deep understanding of them is crucial for anyone studying chemistry.

Atomic Structure

Atomic structure forms the base of ion formation and is paramount to comprehending how elements interact in chemical bonding. An atom consists of a nucleus made up of protons and neutrons, surrounded by an electron cloud. Protons carry a positive charge, neutrons have no charge, and electrons are negatively charged. In a neutral atom, the number of protons equals the number of electrons, resulting in no overall charge.

However, atoms can achieve more stable electron configurations by gaining or losing electrons to become ions. During this process, the balance between protons and electrons shifts. In monatomic ions such as the positively charged potassium ion ((K^+)), the ion has more protons than electrons. In contrast, polyatomic ions like the carbonate ion ((CO_3^{2-})) maintain electrical neutrality by sharing electrons through covalent bonds among multiple atoms, still resulting in a net charge.

Chemical Bonding

Chemical bonding is the glue that holds atoms together in substances, allowing for the variety of materials we encounter. There are several types of chemical bonds, with ionic and covalent bonds being the two main kinds relevant to the formation of ions. Ionic bonding occurs when there is a transfer of electrons from one atom to another, leading to the generation of oppositely charged ions that attract each other, such as in table salt, where sodium ions and chloride ions form a lattice.

In covalent bonding, atoms share pairs of electrons to achieve stability, which is typical in the formation of polyatomic ions. This sharing of electrons is exemplified in the sulfate ion ((SO_4^{2-})), where sulfur and oxygen atoms share electrons, but the entire unit has a charge due to the overall electron distribution. Understanding chemical bonds is essential not only to comprehend how ions are formed but also to predict the properties and reactivity of compounds they constitute.