Problem 36 - Chemistry: Principles and Reactions

Question

Write the names of the following molecules. (a) \(\mathrm{CO}\) (b) \(\mathrm{SiC}\) (c) \(\mathrm{XeF}_{6}\) (d) \(\mathrm{P}_{4} \mathrm{O}_{10}\) (e) \(\mathrm{C}_{2} \mathrm{H}_{2}\)

Step-by-Step Solution

Answer

Answer: The names of the given chemical molecules are as follows: (a) Carbon monoxide, (b) Silicon carbide, (c) Xenon hexafluoride, (d) Tetraphosphorus decoxide, and (e) Diacetylene (also called ethyne).

Step 1: Identify the Elements in Each Molecule

Determine the elements represented by the symbols in each molecule: (a) C: Carbon, O: Oxygen (b) Si: Silicon, C: Carbon (c) Xe: Xenon, F: Fluorine (d) P: Phosphorus, O: Oxygen (e) C: Carbon, H: Hydrogen

Step 2: Determine the Type of Compound

Determine if the compound is a binary molecular compound (composed of nonmetals) or an ionic compound (composed of a metal and nonmetal): (a) CO: Binary molecular compound (b) SiC: Ionic compound (c) XeF6: Binary molecular compound (d) P4O10: Binary molecular compound (e) C2H2: Binary molecular compound

Step 3: Naming Binary Molecular Compounds

Name the binary molecular compounds using the appropriate Greek prefixes for the number of atoms of each element: (a) CO: Carbon monoxide (c) XeF6: Xenon hexafluoride (d) P4O10: Tetraphosphorus decoxide (e) C2H2: Diacetylene (also called ethyne)

Step 4: Naming Ionic Compounds

Name the ionic compound by combining the cation (metal) name and the anion (nonmetal) name, ending in -ide: (b) SiC: Silicon carbide

Key Concepts

Binary Molecular Compounds

Binary molecular compounds are formed by the combination of two nonmetal elements. They are covalently bonded, meaning they share electrons. This bonding occurs because nonmetals generally have similar electronegativities. They do not easily donate or accept electrons like metals, so they share them instead.
When naming binary molecular compounds, we use specific rules that rely heavily on the number of atoms of each element in the compound. Greek prefixes are used for this purpose.Some common binary molecular compounds are:

• Carbon dioxide (\( ext{CO}_2\)
• Nitrogen dioxide \( ext{NO}_2\)
• Carbon monoxide \( ext{CO}\)

In our original examples, CO, XeF₆, P₄O₁₀, and C₂H₂ are all binary molecular compounds. Each is named using the Greek prefixes according to the number of atoms present.

Ionic Compounds

Ionic compounds consist of a combination of metal and nonmetal elements. These compounds form through ionic bonding, where electrons are transferred from the metal to the nonmetal. This transfer creates oppositely charged ions that attract each other strongly, forming a stable compound.

Ionic compounds are typically solid at room temperature, have high melting points, and can conduct electricity when dissolved in water. For example, sodium chloride (\( ext{NaCl}\)), commonly known as table salt, is an ionic compound.For naming ionic compounds:

• The metal (cation) name is written first.
• The nonmetal (anion) name follows, with an '-ide' suffix.

In the given exercise, SiC (silicon carbide) is an example of an ionic compound. Here, silicon acts as the cation, while carbon is the anion.

Greek Prefixes for Naming Compounds

Greek prefixes are essential in the nomenclature of binary molecular compounds. They indicate the number of atoms of each element in a compound. This method helps differentiate between compounds that contain the same elements but in different ratios.
It's important to note that the prefix 'mono-' is sometimes omitted for the first element. However, all other prefixes must be used accurately to avoid misunderstanding. Here is a list of the common Greek prefixes:

• 1 - mono-
• 2 - di-
• 3 - tri-
• 4 - tetra-
• 5 - penta-
• 6 - hexa-
• 7 - hepta-
• 8 - octa-
• 9 - nona-
• 10 - deca-

In our exercise, we used prefixes in the compound names like 'mono-' for CO (carbon monoxide), 'hexa-' for XeF₆ (xenon hexafluoride), 'tetra-' and 'deca-' for P₄O₁₀ (tetraphosphorus decoxide), and 'di-' for C₂H₂ (diacetylene).
This naming system allows for clear communication and proper identification of compounds in chemistry.