Question

Give the name or chemical formula, as appropriate, for each of the following binary molecular substances: \((\mathbf{a}) \mathrm{SF}_{6},(\mathbf{b}) \mathrm{IF}_{5}\), (c) \(\mathrm{XeO}_{3},\) (d) dinitrogen tetroxide, (e) hydrogen cyanide, (f) tetraphosphorus hexasulfide.

Short answer

(a) Sulfur hexafluoride, (b) Iodine pentafluoride, (c) Xenon trioxide, (d) \(\text{N}_2\text{O}_4\), (e) \(\text{HCN}\), (f) \(\text{P}_4\text{S}_6\).

Step-by-step solution

Identify and Name SF6

The first compound is \( \text{SF}_6 \). This is a binary molecular compound made of sulfur and fluorine. Since sulfur is the first element, it retains its elemental name 'sulfur'. The second element is fluorine, which gets '-ide' added to its root name, making it fluoride. The prefix 'hexa-' (meaning six) is used for the six fluorine atoms. Thus, \( \text{SF}_6 \) is named sulfur hexafluoride.

Identify and Name IF5

The second compound is \( \text{IF}_5 \). This compound consists of iodine and fluorine. Iodine retains its name and 'pent-' (meaning five) is the prefix used for the five fluorine atoms. The name becomes iodine pentafluoride.

Identify and Name XeO3

The third compound is \( \text{XeO}_3 \). Xenon keeps its elemental name, and there are three oxygen atoms, which use the prefix 'tri-'. The name of the compound is xenon trioxide since 'oxide' is used for oxygen with the '-ide' ending.

Determine Chemical Formula for Dinitrogen Tetroxide

The compound is dinitrogen tetroxide. 'Di-' means two, and '-tetra' means four. Therefore, the formula will have two nitrogen atoms and four oxygen atoms, written as \( \text{N}_2\text{O}_4 \).

Determine Chemical Formula for Hydrogen Cyanide

Hydrogen cyanide combines a hydrogen atom with the cyanide group \( \text{CN} \). This results in the chemical formula \( \text{HCN} \).

Determine Chemical Formula for Tetraphosphorus Hexasulfide

Tetraphosphorus hexasulfide involves four phosphorus atoms and six sulfur atoms. The prefix 'tetra-' corresponds to four, and 'hexa-' corresponds to six, leading to the formula \( \text{P}_4\text{S}_6 \).

Key concepts

Chemical Nomenclature

Chemical nomenclature is the systematic method of naming chemical compounds. This system helps chemists across the globe to understand exactly what substances are being discussed. For chemical compounds, the naming relies on identifying elements in the compound and using specific rules to assign a name based on their chemical makeup.
When dealing with binary molecular compounds, which are composed of two non-metal elements, these naming rules are quite specific. Here's how it generally works:

• The first element in the compound keeps its regular name, such as sulfur, iodine, or xenon.
• The second element will typically have its name modified to end in '-ide.' This is commonly seen in elements like fluorine becoming fluoride or oxygen becoming oxide.
• Prefixes are added to the elements to indicate the number of atoms present. These prefixes like 'mono-', 'di-', 'tri-', etc., will guide the name's structure.

This system of nomenclature helps in creating clarity and consistency for naming innumerable chemical compounds, allowing for clear communication and identification across different scientific and educational discussions.

Molecular Formulas

Molecular formulas are crucial in representing the composition of chemical substances. They provide a straightforward way of expressing the exact number of atoms of each element in a molecule. For binary molecular compounds, these formulas are typically derived from their names.
For example, when you hear 'dinitrogen tetroxide,' the prefix 'di-' indicates two nitrogen atoms, and 'tetra-' indicates four oxygen atoms. This translates into the molecular formula \(\text{N}_2\text{O}_4\).
Molecular formulas are standardized representations that chemists use to identify and categorize the precise components of a compound, distinguishing it from others. They direct the correct proportions and numbers of atoms, ensuring no ambiguity occurs in chemical communication.
Using molecular formulas aids in easily constructing and predicting the physical and chemical behavior of substances, making them a pivotal part of studying chemistry and understanding molecular interactions.

Chemical Prefixes

Chemical prefixes are indispensable when dealing with binary molecular compounds. They help denote the number of atoms of each element present in a compound. Without these prefixes, the molecular formula and name wouldn't convey enough information about the compound's make-up.
Commonly used prefixes include:

• 'Mono-' for one atom (often omitted in the first element).
• 'Di-' for two atoms.
• 'Tri-' for three atoms.
• 'Tetra-' for four atoms.
• 'Penta-' for five atoms.
• 'Hexa-' for six atoms.

For example, the prefix 'hexa-' in sulfur hexafluoride (\(\text{SF}_6\)) indicates there are six fluorine atoms. These prefixes prevent confusion and ensure each name is unique to its specific chemical structure.
Being aware of these prefixes not only helps in naming compounds but also plays a crucial role in writing their molecular formulas accurately. Understanding and using these prefixes allows students and professionals alike to describe the composition of chemical compounds accurately and efficiently.