Question

(a) Use Lewis symbols to represent the reaction that occurs between Li and O atoms. (b) What is the chemical formula of the most likely product? (c) How many electrons are transferred? (d) Which atom loses electrons in the reaction?

Short answer

(a) The reaction between Li and O using Lewis symbols is: 2Li• + O::: ⟶ [Li⁺]₂O²⁻. (b) The chemical formula of the most likely product is Li₂O. (c) A total of 2 electrons are transferred. (d) The Lithium (Li) atoms lose electrons in the reaction.

Step-by-step solution

Write the electron configuration for the Li and O atoms.

A Lithium (Li) atom has 3 electrons: two in its inner shell and one in its outer shell. The electron configuration can be written as 1s²2s¹. An Oxygen (O) atom has 8 electrons: two in its inner shell and six in its outer shell. The electron configuration can be written as 1s²2s²2p⁴.

Determine the Lewis symbols for Li and O atoms.

The Lewis symbols of elements represent the valence electrons of an atom. A Lithium (Li) atom has 1 valence electron (outer shell), so its Lewis symbol is Li•. An Oxygen (O) atom has 6 valence electrons (outer shell), so its Lewis symbol is O with three lone pairs of electrons: O:::

Represent the reaction between Li and O using Lewis symbols.

A Li• atom will react with an O::: atom to achieve a stable configuration for both atoms. Li• can achieve stability by losing its single valence electron, while O::: can achieve stability by gaining two valence electrons to fill its outer shell. Since one Li atom has only one electron to lose, we need two Li atoms to react with one O atom: 2Li• + O::: ⟶ [Li⁺]₂O²⁻

(b) Determine the chemical formula of the most likely product.

From the Lewis symbols, we can see that two Li⁺ ions and one O²⁻ ion are the products of the reaction, forming an ionic compound. The chemical formula for the most likely product is Li₂O.

(c) Determine the number of electrons transferred.

The Li• atoms lose one electron each to become Li⁺ ions. Since two Li• atoms are involved in the reaction, a total of 2 electrons are transferred.

(d) Identify which atom loses electrons in the reaction.

The Lithium (Li) atoms lose electrons in the reaction. They lose one electron each to become Li⁺ ions. This process is called oxidation. The Oxygen (O) atoms gain electrons, which is called reduction.

Key concepts

Lithium Oxidation

In a chemical reaction between lithium (Li) and oxygen (O), the lithium atom undergoes a process known as oxidation. Oxidation involves the loss of electrons, which results in the transformation of a neutral lithium atom into a positively charged ion (Li⁺). A lithium atom, with its electron configuration of 1s²2s¹, has one valence electron in its outer shell. During oxidation, this single valence electron is transferred to another atom or molecule, leaving behind a positively charged lithium ion. This loss of an electron is what enables lithium to transition from a neutral state to a stable, positively charged state in chemical reactions. For a lithium atom to become stable, it only needs to lose its one valence electron.

Oxygen Reduction

Reduction is the process opposite to oxidation; it involves the gain of electrons. In the lithium-oxygen reaction, oxygen atoms experience reduction. Each oxygen atom, with an electron configuration of 1s²2s²2p⁴, has six valence electrons and requires two more to achieve a stable octet configuration. During the reaction, oxygen atoms gain electrons that are shed by lithium atoms. When an oxygen atom gains these electrons, it becomes reduced and transforms into an oxide ion (O²⁻), which has a full outer shell. Thus, reduction refers to the gaining of electrons, resulting in a negative charge. For oxygen, gaining these electrons completes its valence shell and leads to the formation of a stable ionic compound with lithium.

Electron Transfer

Electron transfer is a fundamental process in the formation of ionic compounds. It involves the movement of electrons from one atom to another. In the reaction between lithium and oxygen, each lithium atom transfers its valence electron to oxygen. This electron transfer results in the formation of lithium ions (Li⁺) and oxide ions (O²⁻). When two lithium atoms each provide one electron, a total of two electrons are transferred to a single oxygen atom. This transfer is crucial because it allows both elements to achieve stable electronic configurations. Electron transfer is what facilitates the attraction between oppositely charged ions, leading to the formation of ionic compounds like lithium oxide (Li₂O).

Ionic Compounds

Ionic compounds are made when metals transfer electrons to non-metals, resulting in the formation of ions that come together due to electrostatic forces. In this case, lithium (a metal) transfers electrons to oxygen (a non-metal), leading to the formation of lithium ions (Li⁺) and oxide ions (O²⁻). These ions are held together by strong ionic bonds due to the attraction of the positive and negative charges. Ionic compounds typically have high melting and boiling points due to the strength of these bonds. They are also usually brittle and can conduct electricity when melted or dissolved in water. The structure of ionic compounds is a balanced combination of cations and anions, resulting in a neutral overall charge.

Chemical Formula

The chemical formula of a compound indicates the ratio of atoms of each element present in a compound. In the reaction between lithium and oxygen, the chemical formula of the product is lithium oxide, represented as Li₂O. This formula conveys that two lithium ions (Li⁺) react with one oxide ion (O²⁻) to form the compound. The subscript numbers in the formula represent the number of ions needed to balance the charges, ensuring a stable, neutral compound. The chemical formula is significant because it provides a concise and precise way to express the composition of a compound, reflecting its elemental makeup and revealing essential details about its ionic nature and stoichiometry.