Question

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

Short answer

a) Sulfur hexafluoride: SF6 b) Iodine pentafluoride: IF5 c) Xenon trioxide: XeO3 d) Dinitrogen tetroxide: N2O4 e) Hydrogen cyanide: HCN f) Tetraphosphorus hexasulfide: P4S6

Step-by-step solution

a) SF6

The chemical formula given is SF6, which consists of one sulfur(S) atom and six fluorine(F) atoms. This binary molecular substance is named Sulfur hexafluoride.

b) IF5

The chemical formula given is IF5, consisting of one iodine(I) atom and five fluorine(F) atoms. The binary molecular substance is named Iodine pentafluoride.

c) XeO3

The chemical formula given is XeO3, which consists of one xenon(Xe) atom and three oxygen(O) atoms. This binary molecular substance is named Xenon trioxide.

d) Dinitrogen tetroxide

The name given is dinitrogen tetroxide, with "di" meaning two nitrogen(N) atoms and "tetra" meaning four oxygen(O) atoms. As a result, the chemical formula is N2O4.

e) Hydrogen cyanide

The name given is hydrogen cyanide, which indicates the compound has one hydrogen(H) atom and one cyanide(CN) group. Therefore, the chemical formula of hydrogen cyanide is HCN.

f) Tetraphosphorus hexasulfide

The name given is tetraphosphorus hexasulfide, with "tetra" meaning four phosphorus(P) atoms and "hexa" meaning six sulfur(S) atoms. Hence, the chemical formula for tetraphosphorus hexasulfide is P4S6.

Key concepts

Binary Molecular Substances

Binary molecular substances are chemical compounds consisting of exactly two different types of non-metal elements. A well-known example of a binary molecular substance is water (H_2O), which comprises two hydrogen atoms bonded to one oxygen atom.

Understanding binary molecular substances begins with recognizing the variety of non-metal elements on the periodic table. When these elements form compounds, they share electrons, resulting in the formation of covalent bonds. Covalent bonding is a hallmark of molecular substances, distinguished from ionic bonding found in compounds consisting of metals and non-metals.

In binary molecular compounds, the first element in the chemical formula is named using its full elemental name, while the second element's name is altered to end with '-ide'. For instance, CO_2 is carbon dioxide, with 'carbon' representing the first element and 'oxide' indicating the presence of oxygen.

Modifiers like 'mono-', 'di-', 'tri-', etc., are added to quantitatively specify the number of atoms of each element present in the compound, as seen in compounds like sulfur hexafluoride (SF_6), meaning one sulfur atom and six fluorine atoms.

Chemical Formulas

Chemical formulas are a way of representing the atoms of elements and their proportion in chemical compounds. They provide essential information at a glance, like the types and quantities of atoms involved, which can help predict the properties and behaviors of the compounds.

A chemical formula has symbols of elements with subscripts denoting the number of atoms of each element in the compound. For example, the formula for hydrogen peroxide is H_2O_2, indicating that there are two hydrogen atoms and two oxygen atoms.

There are several types of chemical formulas, including empirical formulas which represent the simplest whole-number ratio of atoms in a compound, molecular formulas that provide the actual number of atoms of each element in a molecule, and structural formulas that also indicate the arrangement of atoms within the compound. For instance, the molecular formula of glucose is C_6H_12O_6, and its structural formula would show the specific arrangement of these atoms.

Systematic Naming of Compounds

The systematic naming of compounds—also known as nomenclature—is critical for scientists to communicate unambiguously about chemical substances. This system is based on a set of agreed-upon rules established by the International Union of Pure and Applied Chemistry (IUPAC).

For binary molecular substances, the name is constructed by first stating the name of the element with the positive oxidation state (or the less electronegative element), followed by the name of the element with the negative oxidation state (or the more electronegative element), with an appropriate prefix to denote the number of atoms and '-ide' as a suffix. For example, N_2O_4 is called dinitrogen tetroxide, with 'di-' indicating two nitrogen atoms and 'tetra-' indicating four oxygen atoms.

One crucial aspect of systematic naming is the use of Greek prefixes to indicate the number of atoms of each element present in the compound. These prefixes include 'mono-' for one, 'di-' for two, 'tri-' for three, and continuing in a similar fashion for larger numbers of atoms. Though 'mono-' is often omitted for the first element, it is used when needed for clarity, such as in carbon monoxide (CO) versus carbon dioxide (CO_2).