Question

State the number of valence electrons for a lithium ion and an chloride ion in an ionic bond.

Short answer

The lithium ion has 0 valence electrons, and the chloride ion has 8 valence electrons.

Step-by-step solution

Understand Valence Electrons for Lithium Atom

Lithium (Li) is in Group 1 of the periodic table, having an atomic number of 3. In its neutral atomic state, lithium has 3 electrons, with an electronic configuration of 1s² 2s¹. Therefore, a neutral lithium atom has 1 valence electron.

Determine Valence Electrons for Lithium Ion

When lithium forms an ion, it loses its one valence electron to achieve a stable electron configuration of 1s², resembling helium. Thus, a lithium ion (Li⁺) has 0 valence electrons.

Understand Valence Electrons for Chlorine Atom

Chlorine (Cl) is located in Group 17 of the periodic table, and its atomic number is 17. A neutral chlorine atom has an electronic configuration of 1s² 2s² 2p⁶ 3s² 3p⁵, totaling 7 electrons in its outer shell. Therefore, chlorine has 7 valence electrons.

Determine Valence Electrons for Chloride Ion

To form an ion, chlorine gains one electron to complete its outer shell, achieving a configuration similar to argon: 1s² 2s² 2p⁶ 3s² 3p⁶. Therefore, a chloride ion (Cl⁻) still maintains 8 valence electrons after gaining the extra electron.

Key concepts

Ionic Bonds

Ionic bonds are a type of chemical bond that forms between atoms when they transfer electrons from one to another. This transfer leads to the formation of ions, where one atom becomes positively charged (cation) and the other negatively charged (anion). The electrostatic attraction between these oppositely charged ions holds them together in a stable compound.

Within an ionic bond, the metal atom typically loses one or more electrons, becoming a cation, while the non-metal atom gains those electrons, becoming an anion. For instance, in a lithium chloride (LiCl) compound, lithium loses an electron to become Li⁺, and chlorine gains an electron to become Cl⁻.

This transfer of electrons allows each atom to achieve a more stable electronic configuration, often resembling that of the nearest noble gas in the periodic table. Because of this stability, ionic bonds are fundamental in the formation of various compounds essential in chemistry.

Electron Configuration

Electron configuration refers to the arrangement of electrons around the nucleus of an atom. It is represented by numerical notations and symbols that describe the distribution of electrons in different atomic orbitals.

For example, the electron configuration of a neutral lithium atom is 1s² 2s¹. This indicates that lithium has its first two electrons in the first energy level (the 1s orbital) and one electron in the second energy level (the 2s orbital). When lithium loses an electron to become a Li⁺ ion, its configuration becomes 1s², resembling the electron configuration of helium.

Electron configurations play a crucial role in determining how atoms interact and bond with each other. They provide insight into valence electrons, which are primarily involved in forming chemical bonds. Understanding electron configurations thus enables us to predict and explain the chemical behavior of different elements, especially in the context of ionic bond formation.

Ions

Ions are atoms or molecules that have gained or lost one or more electrons, resulting in a positive or negative charge. Depending on whether they lose or gain electrons, they are classified into two types:

• Cations: Positively charged ions formed when atoms lose electrons (e.g., Li⁺).
• Anions: Negatively charged ions formed when atoms gain electrons (e.g., Cl⁻).

Ions are essential in the formation of ionic compounds, where metal atoms typically lose electrons to become cations while non-metal atoms gain electrons to become anions. For instance, when lithium (a metal) loses an electron, it becomes a cation (Li⁺), while chlorine (a non-metal) gains an electron to become an anion (Cl⁻).

This exchange leads to the electrostatic attraction that forms an ionic bond, resulting in compounds that are critical in a wide range of chemical processes.

Periodic Table

The periodic table is a comprehensive chart that organizes all known chemical elements based on their atomic number, electron configuration, and recurring chemical properties. It is a crucial tool for chemists and students alike.

Each element in the periodic table is arranged into rows (periods) and columns (groups). Elements in the same group share similar chemical behaviors because they have the same number of valence electrons. For example, lithium is in Group 1, indicating it has one valence electron, while chlorine is in Group 17, signifying it has seven valence electrons.

Knowing an element's position on the periodic table helps predict its reactivity and bonding tendencies, including its tendency to form ions. Thus, it is a foundational reference for understanding and predicting the outcome of chemical reactions, such as the formation of ionic bonds.

Chemical Stability

Chemical stability refers to the tendency of a chemical system to remain unchanged over time. It often involves achieving a complete outer electron shell, which is associated with lower energy and greater stability. This is particularly relevant for elements seeking to form stable compounds.

Elements are driven to achieve a stable electronic configuration often similar to the nearest noble gas. For example, lithium achieves stability by losing one electron to form a Li⁺ ion, resembling helium, while chlorine gains one electron to form Cl⁻, resembling argon.

In the context of ionic bonds, the transfer of electrons allows atoms to achieve chemical stability. As a result, the compound formed, such as lithium chloride (LiCl), consists of ions with complete electron shells. This stability is a key factor in why such compounds are often found in nature and are essential in many industrial processes.