Naming Binary Molecular Compounds: Videos & Practice Problems

Binary molecular compounds consist of two different nonmetals, such as water (H₂O) and nitrogen oxides (NO). Naming these compounds involves using numerical prefixes: mono (1), di (2), tri (3), tetra (4), penta (5), hexa (6), hepta (7), octa (8), nona (9), and deca (10). The first nonmetal retains its name without "mono," while the second adopts the "ide" suffix. If a prefix ending in 'a' precedes 'o', the 'a' is dropped, as in "tetroxide" for four oxygens. Understanding these rules is essential for accurate chemical communication.

Naming Binary Molecular Compounds Concept 1

Binary molecular compounds are formed from two different nonmetal elements. Common examples include water (H₂O), which consists of hydrogen and oxygen, and nitrogen oxides, such as NO (nitric oxide), where nitrogen and oxygen combine. These compounds are characterized by their ability to form in various proportions, necessitating the use of numerical prefixes to indicate the number of atoms of each element present in the compound.

The numerical prefixes used in naming these compounds are essential for clarity. They include:

• Mono- (1)
• Di- (2)
• Tri- (3)
• Tetra- (4)
• Penta- (5)
• Hexa- (6)
• Hepta- (7)
• Octa- (8)
• Nona- (9)
• Deca- (10)

When naming binary molecular compounds, the prefix is used to denote the number of atoms of each element. For instance, CO is named carbon monoxide, while CO₂ is carbon dioxide. Understanding these prefixes is crucial for accurately identifying and communicating the composition of binary molecular compounds.

Naming Binary Molecular Compounds Concept 2

When naming binary molecular compounds, it is essential to follow specific rules to ensure clarity and accuracy. The first nonmetal in the compound is named using its standard name, accompanied by numerical prefixes to indicate the number of atoms present, except for the prefix "mono," which is never used for the first element. For the second nonmetal, its base name is retained, and it also uses numerical prefixes, but its name must end with the suffix "ide." This indicates that it is part of a binary compound.

Additionally, when a numerical prefix that ends with the letter "a" is adjacent to a prefix that starts with the letter "o," the "a" is typically dropped to avoid awkward pronunciation. For instance, the compound with four oxygen atoms would be referred to as "tetroxide" instead of "tetraoxide," as the "a" from "tetra" is omitted when followed by "oxide." By adhering to these naming conventions, one can accurately identify and communicate the composition of binary molecular compounds.

Naming Binary Molecular Compounds Example 1

When writing chemical formulas for compounds, it's essential to understand the prefixes that indicate the number of atoms present in each element. For example, in the compound disulfur monochloride, the prefix "di-" signifies two sulfur atoms, represented as S2, while "mono-" indicates one chlorine atom, leading to the formula S2Cl.

Next, consider tetraphosphorus pentaselenide. The prefix "tetra-" means four, so we have four phosphorus atoms, written as P4. The prefix "penta-" indicates five selenium atoms, represented as Se. Therefore, the complete formula is P4Se5.

Lastly, for dibromoheptoxide, "di-" indicates two bromine atoms, which is Br2. The prefix "hept-" refers to seven, and since "oxide" indicates oxygen, we have seven oxygen atoms, resulting in O7. Thus, the formula for dibromoheptoxide is Br2O7.

In summary, when constructing formulas for molecular compounds, the first nonmetal retains its elemental name and uses numerical prefixes (except for "mono-"), while the second nonmetal also uses numerical prefixes but changes its ending to "-ide."

Give the systematic name for the following compound:SeF₆

• A. selenium fluoride
• B. selenium hexafluoride
• C. monoselenium hexafluoride
• D. monoselenium fluoride
• E. selenium fluorite

Answer: (B)

Give the systematic name for the following compound:IO₅

• A. iodine oxide
• B. monoiodine oxide
• C. iodine pentoxide
• D. iodide pentoxide
• E. monoiodide pentoxide

Answer: (C)

Give the systematic name for the following compound:N₂S₄

• A. nitrogen tetrasulfide
• B. dinitrogen tetrasulfide
• C. dinitrogen sulfide
• D. nitrogen sulfide
• E. nitrogen sulfite

Answer: (B)

Here’s what students ask on this topic:

What are binary molecular compounds and how are they named?

Binary molecular compounds consist of two different nonmetals, such as water (H₂O) and nitrogen oxides (NO). Naming these compounds involves using numerical prefixes to indicate the number of atoms of each element. The first nonmetal retains its name without the prefix 'mono,' while the second nonmetal adopts the 'ide' suffix. For example, CO is carbon monoxide, and CO₂ is carbon dioxide. If a prefix ending in 'a' precedes 'o', the 'a' is dropped, as in 'tetroxide' for four oxygens. Understanding these rules is essential for accurate chemical communication.

What are the numerical prefixes used in naming binary molecular compounds?

The numerical prefixes used in naming binary molecular compounds are: mono (1), di (2), tri (3), tetra (4), penta (5), hexa (6), hepta (7), octa (8), nona (9), and deca (10). These prefixes indicate the number of atoms of each element in the compound. For example, N₂O₄ is named dinitrogen tetroxide, where 'di' indicates two nitrogen atoms and 'tetra' indicates four oxygen atoms.

Why is the prefix 'mono' not used for the first nonmetal in binary molecular compounds?

The prefix 'mono' is not used for the first nonmetal in binary molecular compounds to avoid redundancy and simplify naming. For example, CO is named carbon monoxide, not monocarbon monoxide. This convention helps streamline the naming process and makes the names easier to pronounce and remember.

How do you name a binary molecular compound with the formula P₂O₅?

To name the binary molecular compound P₂O₅, follow these steps: First, name the first nonmetal (phosphorus) and use the appropriate numerical prefix (di) to indicate two atoms, resulting in 'diphosphorus.' Next, name the second nonmetal (oxygen) with the 'ide' suffix and the appropriate numerical prefix (penta) to indicate five atoms, resulting in 'pentoxide.' Therefore, P₂O₅ is named diphosphorus pentoxide.

What is the rule for dropping the letter 'a' in numerical prefixes when naming binary molecular compounds?

When naming binary molecular compounds, if a numerical prefix ending in 'a' is followed by a nonmetal name starting with 'o,' the 'a' is dropped to avoid awkward pronunciation. For example, 'tetraoxide' becomes 'tetroxide.' This rule helps make the names of compounds easier to say and more fluid.