Question

Give the name and formula of each of the binary compounds formed from the following elements. a. Li and N b. Na and Br c. K and S

Short answer

The binary compounds formed are as follows: a. Lithium Nitride (Li₃N) b. Sodium Bromide (NaBr) c. Potassium Sulfide (K₂S)

Step-by-step solution

a. Li and N Binary Compound Formation

First, we will identify the valency of the elements. - Lithium (Li) is an alkali metal with a valency of +1 (loses 1 electron). - Nitrogen (N) is a non-metal with a valency of -3 (gains 3 electrons). Now, we will use the valencies to make them equal by taking the least common multiple. - Lithium Nitride (Li₃N): \(3 \times (+1)\) for Li to balance \(1 \times (-3)\) for N. So, the formula for the binary compound formed by Li and N is Li₃N, and the compound's name is Lithium Nitride.

b. Na and Br Binary Compound Formation

First, we will identify the valency of the elements. - Sodium (Na) is an alkali metal with a valency of +1 (loses 1 electron). - Bromine (Br) is a halogen with a valency of -1 (gains 1 electron). Now, we will use the valencies to make them equal. - Sodium Bromide (NaBr): \(1 \times (+1)\) for Na to balance \(1 \times (-1)\) for Br. So, the formula for the binary compound formed by Na and Br is NaBr, and the compound's name is Sodium Bromide.

c. K and S Binary Compound Formation

First, we will identify the valency of the elements. - Potassium (K) is an alkali metal with a valency of +1 (loses 1 electron). - Sulfur (S) is a non-metal with a valency of -2 (gains 2 electrons). Now, we will use the valencies to make them equal by taking the least common multiple. - Potassium Sulfide (K₂S): \(2 \times (+1)\) for K to balance \(1 \times (-2)\) for S. So, the formula for the binary compound formed by K and S is K₂S, and the compound's name is Potassium Sulfide.

Key concepts

Understanding Valency

When studying chemical compounds, valency is a critical concept to grasp. Valency refers to the ability of an atom to bond with another, often dictated by the number of electrons an atom can donate, accept, or share.
- For metals like Lithium (Li), Sodium (Na), and Potassium (K), the typical valency is +1. This means these metals tend to lose one electron during reactions. - For non-metals like Nitrogen (N) and Sulfur (S), the valency typically involves gaining electrons. Nitrogen has a valency of -3 because it gains three electrons, while sulfur gains two, resulting in a valency of -2. - Halogens like Bromine (Br) usually have a valency of -1, as they gain one electron. Understanding valencies helps predict and explain the chemical behavior of elements. By balancing the valencies of two elements, we can deduce the correct formula of the compound they form.

Constructing Chemical Formulas

Chemical formulas are essential for representing the specific combination of elements in a compound. They demonstrate not only the elements involved but also their proportions.
- When constructing a chemical formula, it's crucial to ensure that the total positive and negative charges within the compound balance out to zero. This is often achieved by taking the least common multiple of their valencies. - For binary compounds like those formed in our examples, we combine the valencies of the two elements to ascertain how many of each are needed. For instance, pairing Lithium (Li) with its valency of +1 and Nitrogen (N) with -3 leads to forming Lithium Nitride (Li₃N). - Similarly, Sodium (Na) with +1 and Bromine (Br) with -1 yield Sodium Bromide (NaBr), while Potassium (K) with +1 and Sulfur (S) with -2 create Potassium Sulfide (K₂S). By applying this principle, the correct chemical formula is easily determined, offering a glimpse into the compound's structure and stoichiometry.

The Art of Naming Compounds

Naming compounds, especially binary ones, follows systematic rules to avoid confusion and ensure consistency in chemistry.
- Binary compounds are named using the names of the two elements, adjusting the second element's name to end in "-ide". For instance, combining Li and N forms Lithium Nitride. - The element with a positive valency, typically the metal, is named first, such as Sodium (Na) in Sodium Bromide (NaBr). - For compounds with elements like Potassium and Sulfur, it's crucial to represent the non-metal with the ending "-ide", leading to Potassium Sulfide (K₂S). These naming conventions are essential for clear communication within the scientific community. By adhering to these rules, we ensure that each compound is both easily recognized and understood globally.