Question

Give the proper name for each molecule. a) \(\mathrm{SeO}_{2}\) b) \(\mathrm{Cl}_{2} \mathrm{O}\) c) \(\mathrm{XeF}_{6}\)

Short answer

a) Selenium dioxide, b) Dichlorine monoxide, c) Xenon hexafluoride.

Step-by-step solution

Naming the First Molecule

The molecule \( \mathrm{SeO}_{2} \) consists of one selenium (Se) atom and two oxygen (O) atoms. To name it, use the element name for the first element (selenium) and use the prefix 'di-' for the two oxygen atoms, followed by 'oxide'. Thus, the name of \( \mathrm{SeO}_{2} \) is selenium dioxide.

Naming the Second Molecule

The molecule \( \mathrm{Cl}_{2} \mathrm{O} \) contains two chlorine (Cl) atoms and one oxygen (O) atom. In this case, use the prefix 'di-' for the two chlorine atoms and follow it with the word 'oxide' for the oxygen atom, given no prefix is needed if there is only one atom present. Therefore, \( \mathrm{Cl}_{2} \mathrm{O} \) is dichlorine monoxide.

Naming the Third Molecule

The molecule \( \mathrm{XeF}_{6} \) includes one xenon (Xe) atom and six fluorine (F) atoms. Use the element name for xenon, and for the six fluorine atoms, use the prefix 'hexa-', combined with 'fluoride'. Thus, the name of \( \mathrm{XeF}_{6} \) is xenon hexafluoride.

Key concepts

Binary Compounds

Binary compounds are chemical compounds composed of only two different elements. In the realm of chemistry, understanding how to name these compounds is crucial for communication and comprehension. When you encounter a binary compound, it's made up of two distinct elements, like selenium and oxygen in the compound selenium dioxide.
These compounds can either be ionic or covalent. It's important to distinguish between the two because their naming conventions differ. In our exercise, the compounds are covalent since they involve nonmetals bonding together.
To name binary covalent compounds, you follow specific rules that involve the names of the elements and possibly prefixes to denote the numbers of each kind of atom present. The first element in the formula does not use a prefix unless it's necessary to avoid confusion, while the second element's name often gets altered with an -ide suffix. This naming convention makes the nature of the compound more apparent to those reading the chemical formula.
Understanding binary compounds is essential for anyone studying chemistry, as they are a fundamental component of countless chemical reactions and compounds.

Molecular Prefixes

Molecular prefixes are integral to the naming of chemical compounds, providing essential details about the number of atoms of each element present in a compound.
These prefixes allow chemists to convey the composition of a molecule precisely and accurately. If you were to encounter the molecule \( \mathrm{Cl}_{2} \mathrm{O} \), knowing that 'di-' signifies two would lead you to understand that there are two chlorine atoms involved. Therefore, you would name it dichlorine monoxide.

• The prefix 'mono-' is used to indicate the presence of one atom, although it is often omitted for the first element.
• 'Di-' means two, essential for specifying compounds like \( \mathrm{SeO}_{2} \) or \( \mathrm{Cl}_{2} \mathrm{O} \).
• 'Tri-' indicates three atoms, and 'tetra-' indicates four.
• As more atoms are present, prefixes like 'penta-', 'hexa-', 'hepta-', and 'octa-' are used for numbers five through eight respectively.

These prefixes ensure clarity in naming, which is crucial for the understanding and documentation of chemical compounds. They are a universal language in chemistry, allowing scientists across the globe to understand the composition of molecules unambiguously.

IUPAC Naming Rules

The International Union of Pure and Applied Chemistry (IUPAC) sets the standardized rules for naming chemical compounds, ensuring uniformity across scientific disciplines and languages. These rules define how compounds are named based on their structure and composition, which is essential for international collaboration and education in the sciences.

When naming compounds like in the exercise, you follow IUPAC naming conventions:

• The name starts with the more electropositive element, which is also the first element listed in the chemical formula. This is usually a nonmetal further left on the periodic table.
• The name of the second element is modified to end in -ide, such as oxide from oxygen or fluoride from fluorine.
• For covalent compounds, you use appropriate prefixes to denote the number of atoms present, as outlined previously.

An example of this is \( \mathrm{XeF}_{6} \), which follows the rule by beginning with "xenon" (as it is more electropositive compared to fluorine) and ends with "hexafluoride".

Understanding IUPAC rules allows chemists to write and interpret formulas and chemical names without ambiguity. These rules facilitate the accurate communication of complex chemical information across scientific communities and industries worldwide. Whether you are a student or an experienced chemist, mastering IUPAC naming rules is essential for success in the field of chemistry.