Condensed Formula: Videos & Practice Problems

Condensed formulas represent the bonding of atoms in a compound without showing all individual bonds. For example, CH₃CH₂CH₃ illustrates a straight-chain alkane. Parentheses indicate branched structures, such as (CH₃) in a more complex molecule. Additionally, subscripts in parentheses denote repeating units, allowing for further condensation, as seen in CH₃(CH₂)₂CH₃. Understanding these representations is crucial for grasping molecular structures and their complexities in organic chemistry.

Condensed Formula Concept 1

In chemistry, the condensed formula provides a simplified representation of a compound, illustrating how atoms are grouped without detailing every bond. For instance, in the condensed formula CH₃, the three hydrogen atoms are grouped with the carbon atom, indicating that they are bonded together. Similarly, CH₂ shows two hydrogen atoms bonded to a carbon atom, while CH represents a single carbon atom bonded to one hydrogen atom.

In contrast, the structural formula explicitly displays all the bonds between atoms, including carbon-carbon and carbon-hydrogen connections. This clarity is essential for understanding the molecular structure. For example, when transitioning from a structural formula to a condensed formula, we can group the atoms together. The structural representation of a molecule might show the bonds between carbons, but in the condensed version, we can write it as CH₃CH₂CH₃, effectively condensing the information.

To further simplify, we can eliminate the visual representation of the carbon-carbon bonds, resulting in a fully condensed formula that still conveys the same information about the molecular structure. This method of representation is particularly useful for larger organic compounds, allowing chemists to quickly understand the composition and connectivity of the atoms involved.

Condensed Formula Example 1

To derive the condensed formula for a compound with the molecular formula C₄H₁₀, we start by arranging all four carbon atoms in a linear sequence. Each carbon atom forms four bonds, which means we need to distribute hydrogen atoms accordingly to satisfy this bonding requirement.

In the structural representation, we connect the carbon atoms to each other and then add hydrogen atoms. The first carbon (C) is bonded to three hydrogens (H), represented as CH₃. The next two carbons each bond with two hydrogens, represented as CH₂. The final carbon again bonds with three hydrogens, also represented as CH₃.

When we combine these components, the condensed formula for the compound is CH₃CH₂CH₂CH₃. This notation effectively summarizes the structure while indicating the connectivity of the atoms in the molecule.

Parenthesis and Parenthesis w/ Subscripts Concept 2

Understanding condensed formulas is essential for representing organic compounds, especially when dealing with branched structures. In these formulas, groups enclosed in parentheses indicate branches off the main carbon chain. For instance, consider the structural formula of a compound with three carbon atoms in a row, where a CH₃ group branches off the middle carbon. When converting this structural representation into a condensed formula, we start with the CH₃ group, followed by a CH group. The branched CH₃ group is then placed in parentheses to signify its branching from the main chain.

As we progress to more complex molecules, the use of parentheses becomes increasingly important to accurately depict the structure of the compound. This notation allows chemists to clearly communicate the arrangement of atoms and the presence of branches, which is crucial for understanding the compound's properties and reactivity. By mastering the use of condensed formulas and parentheses, students can effectively represent and analyze a wide variety of organic compounds.

Condensed Formula Example 2

To write the condensed formula for the described compound, we start by identifying the main carbon chain and its branches. The structure begins with a methyl group (CH₃), which is connected to a carbon (CH) that has a chlorine (Cl) branch. This carbon is further connected to another carbon (CH) that has a bromine (Br) branch. Finally, this carbon connects to another methyl group (CH₃).

The condensed formula is structured to reflect these connections and branches clearly. We begin with the first methyl group, followed by the carbon chain, and use parentheses to indicate the branches. Thus, the condensed formula can be written as:

CH₃CH(Cl)CH(Br)CH₃

This notation effectively represents the compound, showing the two branches of chlorine and bromine attached to the carbon chain.

Condensed Formula with Subscript Concept 3

In the study of condensed formulas, parentheses with subscripts play a crucial role in indicating repeating units within a molecular structure. For instance, consider the hydrocarbon represented by the structural formula CH₃CH₂CH₂CH₃. To convert this into a condensed formula, we can start by writing it as CH₃ followed by CH₂, CH₂, and then CH₃. However, this can be further simplified.

By recognizing that the two CH₂ units in the middle are identical, we can condense the formula even more. This is achieved by placing the repeating units in parentheses and adding a subscript to indicate the number of times the unit repeats. Thus, the condensed formula can be expressed as CH₃(CH₂)₂CH₃. This notation effectively communicates the structure of the hydrocarbon while highlighting the presence of repeating units, making it a more efficient representation.

Condensed Formula Example 3

To draw the structure corresponding to the condensed formula CH3(CH2)3CH3, we start by identifying the components of the formula. The first part, CH3, indicates a carbon atom bonded to three hydrogen atoms, which forms a methyl group.

Next, the (CH2)3 indicates that there are three methylene groups (each CH2 consists of one carbon atom bonded to two hydrogen atoms) connected in a chain. These methylene groups are linked to the initial methyl group and to each other. Finally, the last CH3 signifies another methyl group at the end of the chain.

In summary, the structural representation begins with a methyl group, followed by three methylene groups in the center, and concludes with another methyl group. This arrangement illustrates a straight-chain alkane, specifically hexane, with the molecular formula C6H14.

Write a condensed formula for the given structure.

• A. CH₃CH(CH₃)CH(NH₂)CH₃
• B. C₅H₁₃N
• C. CH₃CH(CH₂)CH₃(NH₂)CH₃
• D. (CH)₂(CH₃)₃NH₂

Answer: (A)

Convert CH₃(CH₂)₂CHBrCH₃ into structural formula.

• A.
• B.
• C.
• D.

Answer: (C)

Here’s what students ask on this topic:

What is a condensed formula in organic chemistry?

A condensed formula in organic chemistry is a way to represent the bonding of atoms in a compound without showing all individual bonds. It groups carbon and hydrogen atoms together in blocks, such as CH₃ or CH₂, to simplify the structure. For example, the condensed formula CH₃CH₂CH₃ represents a straight-chain alkane with three carbon atoms and eight hydrogen atoms. This method helps in visualizing the molecular structure more compactly.

How do parentheses and subscripts work in condensed formulas?

In condensed formulas, parentheses indicate branched structures or repeating units. For example, in a branched structure, (CH₃) denotes a methyl group attached to the main chain. Subscripts in parentheses indicate the number of repeating units. For instance, CH₃(CH₂)₂CH₃ means there are two CH₂ groups in the middle of the molecule. This notation helps in further condensing the formula and simplifying complex structures.

Why are condensed formulas important in organic chemistry?

Condensed formulas are important in organic chemistry because they provide a simplified way to represent complex molecular structures. They help in visualizing the arrangement of atoms without drawing all individual bonds, making it easier to understand and communicate molecular structures. This is particularly useful for large molecules and helps in identifying functional groups, branches, and repeating units efficiently.

Can you give an example of converting a structural formula to a condensed formula?

Sure! Let's take the structural formula of butane: CH₃-CH₂-CH₂-CH₃. To convert this to a condensed formula, we group the carbon and hydrogen atoms together: CH₃CH₂CH₂CH₃. We can further condense it by recognizing the repeating CH₂ units: CH₃(CH₂)₂CH₃. This shows the same molecule in a more compact form.

How do you represent branched structures in condensed formulas?

Branched structures in condensed formulas are represented using parentheses. For example, if a methyl group (CH₃) branches off the main chain, it is placed in parentheses. Consider the structural formula: CH₃-CH(CH₃)-CH₃. The condensed formula would be CH₃CH(CH₃)CH₃, indicating that the CH₃ group is attached to the second carbon of the main chain.