Question

Give the proper name for each molecule. a) \(\mathrm{P}_{4} \mathrm{O}_{10}\) b) \(\mathrm{B}_{2} \mathrm{O}_{3}\) c) \(\mathrm{P}_{2} \mathrm{~S}_{3}\)

Short answer

a) Tetraphosphorus decoxide, b) Diboron trioxide, c) Diphosphorus trisulfide.

Step-by-step solution

Understanding Molecular Structures

To name each compound correctly, we need to understand the rules for naming molecular compounds. Molecular compounds consist of nonmetals. Typically, prefixes are used to indicate the number of atoms of each element present in the compound.

Naming \\ \mathrm{P}_{4} \mathrm{O}_{10}

The subscript '4' indicates that there are four phosphorus atoms, and '10' indicates ten oxygen atoms. The prefix for four is 'tetra', and for ten, it is 'deca'. Thus, the name of \(\mathrm{P}_{4} \mathrm{O}_{10}\) is 'tetraphosphorus decoxide'.

Naming \\ \mathrm{B}_{2} \mathrm{O}_{3}

The subscript '2' indicates that there are two boron atoms, and '3' indicates three oxygen atoms. The prefix for two is 'di', and for three, it is 'tri'. Therefore, the name of \(\mathrm{B}_{2} \mathrm{O}_{3}\) is 'diboron trioxide'.

Naming \\ \mathrm{P}_{2} \mathrm{S}_{3}

For \(\mathrm{P}_{2} \mathrm{S}_{3}\), the subscript '2' indicates two phosphorus atoms and '3' indicates three sulfur atoms. The prefix for two is 'di', and the prefix for three is 'tri'. Therefore, the name of \(\mathrm{P}_{2} \mathrm{S}_{3}\) is 'diphosphorus trisulfide'.

Key concepts

Prefixes in Chemical Names

Prefixes play a vital role when naming molecular compounds. They provide essential information about the number of atoms of each element in the compound. Recognizing these prefixes not only simplifies the process of identifying compounds but also enhances your understanding of chemical nomenclature:

• Mono-: Indicates 1 atom. This prefix is often omitted when it relates to the first element.
• Di-: Indicates 2 atoms.
• Tri-: Indicates 3 atoms.
• Tetra-: Indicates 4 atoms.
• Penta-: Indicates 5 atoms.
• Hexa-: Indicates 6 atoms.
• Hepta-: Indicates 7 atoms.
• Octa-: Indicates 8 atoms.
• Nona-: Indicates 9 atoms.
• Deca-: Indicates 10 atoms.

These prefixes are directly attached to the element names and give an immediate clue about the molecule's composition. For example, 'tetraphosphorus' indicates four phosphorus atoms, while 'trioxide' suggests three oxygen atoms in \(\mathrm{B}_{2} \mathrm{O}_{3}\). Understanding these prefixes can make the naming of molecular compounds much more intuitive and manageable.

Naming Compounds

Naming compounds follows a systematic approach guided by established rules and conventions. This ensures that the names are clear and consistent worldwide.The first step in naming a compound is identifying whether the compound is ionic or molecular. For molecular compounds consisting of nonmetals, prefixes are employed to denote the number of each type of atom.When naming a molecular compound:

• The element with the lower group number in the periodic table comes first, and its full elemental name is used.
• The second element is named using its root and is modified to end in '-ide.'
• Appropriate prefixes from the list above are applied to indicate the number of atoms. If the first element has only one atom, the prefix 'mono-' is typically omitted.

Let's consider the example \(\mathrm{P}_{2} \mathrm{~S}_{3}\):- 'P' (phosphorus) comes first as it falls to the left of sulfur ('S') on the periodic table.- 'S' is named as 'sulfide' due to the '-ide' ending rule.- The appropriate prefixes 'di-' for two phosphorus atoms and 'tri-' for three sulfur atoms are then added, resulting in the name 'diphosphorus trisulfide'.Developing a precise understanding of these naming rules can significantly enhance your ability to work with molecular compounds.

Molecular Compounds

Molecular compounds are a category of compounds where atoms are bonded together by shared pairs of electrons, known as chemical bonds. These types of compounds primarily involve nonmetal elements and reflect intricate bonding between atoms to create stable entities.Some intrinsic characteristics define molecular compounds:

• They usually form between nonmetals and often include elements such as carbon, oxygen, nitrogen, and sulfur, among others.
• The names of molecular compounds are crafted from the elements involved and the number of each type of atom present, clearly indicated by prefixes.
• The chemical bonds in molecular compounds are covalent, meaning that electrons are shared between the atoms rather than being transferred or traded as seen in ionic compounds.
• Molecular compounds can consist of a few atoms like in \(\mathrm{H}_{2}\) (dihydrogen) or larger complex molecules like \(\mathrm{C}_{6}\mathrm{H}_{12}\mathrm{O}_{6}\) (glucose).

Understanding molecular compounds and their nature offers pivotal insights into the foundations of chemistry, signaling how molecules form and how chemical interactions govern the behavior of substances.