Question

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

Short answer

The names or chemical formulas for each of the given binary molecular substances are: (a) \(\mathrm{SF}_{6}\) - sulfur hexafluoride (b) \(\mathrm{IF}_{5}\) - iodine pentafluoride (c) \(\mathrm{XeO}_{3}\) - xenon trioxide (d) dinitrogen tetroxide - \(\mathrm{N}_{2}\mathrm{O}_{4}\) (e) hydrogen cyanide - \(\mathrm{HCN}\) (f) tetraphosphorus hexasulfide - \(\mathrm{P}_{4}\mathrm{S}_{6}\)

Step-by-step solution

Convert chemical formulas to names

For the given chemical formulas, we need to convert them to names. To do this, we first need to identify the elements in each formula. Then, we use the appropriate prefixes to indicate the number of atoms of each element and combine them into the name. (a) \(\mathrm{SF}_{6}\) - sulfur hexafluoride We have one sulfur atom and six fluoride atoms. Therefore, the name is sulfur hexafluoride. (b) \(\mathrm{IF}_{5}\) - iodine pentafluoride We have one iodine atom and five fluoride atoms. Therefore, the name is iodine pentafluoride. (c) \(\mathrm{XeO}_{3}\) - xenon trioxide We have one xenon atom and three oxygen atoms. Therefore, the name is xenon trioxide.

Convert names to chemical formulas

For the given compound names, we need to convert them to chemical formulas. To do this, we first need to identify the elements in each name and the prefix used to indicate the number of atoms of each element. Then, we write the chemical formula accordingly. (d) dinitrogen tetroxide - \(\mathrm{N}_{2}\mathrm{O}_{4}\) We have two nitrogen atoms (dinitrogen) and four oxygen atoms (tetroxide). Thus, the chemical formula is \(\mathrm{N}_{2}\mathrm{O}_{4}\). (e) hydrogen cyanide - \(\mathrm{HCN}\) We have one hydrogen atom (hydrogen) and one cyanide group (CN). Thus, the chemical formula is \(\mathrm{HCN}\). (f) tetraphosphorus hexasulfide - \(\mathrm{P}_{4}\mathrm{S}_{6}\) We have four phosphorus atoms (tetraphosphorus) and six sulfur atoms (hexasulfide). Thus, the chemical formula is \(\mathrm{P}_{4}\mathrm{S}_{6}\). Now, we have provided the names or chemical formulas for each of the given binary molecular substances: (a) \(\mathrm{SF}_{6}\) - sulfur hexafluoride (b) \(\mathrm{IF}_{5}\) - iodine pentafluoride (c) \(\mathrm{XeO}_{3}\) - xenon trioxide (d) dinitrogen tetroxide - \(\mathrm{N}_{2}\mathrm{O}_{4}\) (e) hydrogen cyanide - \(\mathrm{HCN}\) (f) tetraphosphorus hexasulfide - \(\mathrm{P}_{4}\mathrm{S}_{6}\)

Key concepts

Chemical Formula

Understanding a chemical formula is critical for students beginning to explore the field of chemistry. A chemical formula represents the types and numbers of atoms present in a molecular substance. For instance, in the chemical formula \(\mathrm{SF}_{6}\), we're looking at a molecule composed of one sulfur atom and six fluorine atoms. The subscript number tells us exactly how many of each atom there are. If there's no subscript after an element symbol, such as the hydrogen in \(\mathrm{HCN}\), it means there's one atom of that element in the molecule.

In order to write a correct chemical formula, it's necessary to know the valency or combining power of the elements involved, which dictates how atoms bond with each other. For binary molecular compounds, which only contain two types of atoms, determining the chemical formula often involves using these valencies to ensure that the compound is electrically neutral. By mastering how to read and write chemical formulas, students can predict the structure and properties of compounds, further enabling them to understand reactions and interactions in chemistry.

Naming Chemical Compounds

Naming chemical compounds requires a systematic approach to ensure clear communication across the scientific community. Binary molecular compounds are named by using prefixes to indicate the number of atoms present, followed by the names of the elements involved. It is essential to use the correct prefix such as mono- (1), di- (2), tri- (3), and so forth, followed by the name of the first element. For the second element, its name is modified to end in '-ide.' For example, \(\mathrm{N}_{2}\mathrm{O}_{4}\) is named dinitrogen tetroxide. The prefix 'di-' indicates two nitrogen atoms, and 'tetra-' signifies four oxygen atoms, with 'oxide' referring to the oxygen element.

Students can enhance their understanding by practicing the naming of different compounds and learning the exceptions to these rules. For instance, the prefix 'mono-' is often omitted when the first element would have a subscript of one, such as in carbon dioxide (CO2) rather than monocarbon dioxide. It's worth noticing that another convention is used for ionic compounds (those formed between metals and nonmetals), stressing the need to understand the nature of the compound before naming it.

Molecular Substance

A molecular substance refers to a chemical compound that is made up of molecules, which are groups of atoms bonded together. In the context of binary molecular compounds such as \(\mathrm{SF}_{6}\) or \(\mathrm{IF}_{5}\), we are looking at substances made from two different non-metal elements. These bonds are covalent, meaning the atoms share electrons to achieve stability.

Understanding the nature of a molecular substance can help students predict properties such as boiling and melting points, solubility, and reactivity. For example, molecular substances tend to have lower melting and boiling points than ionic compounds because the forces holding the molecules together, known as van der Waals forces, are generally weaker than the ionic bonds found in salts. By recognizing that a compound is a molecular substance, students can begin to infer its physical and chemical properties, leading to a deeper comprehension of the material they encounter in chemistry.