Question

Methanamine, \(\mathrm{CH}_{5} \mathrm{~N}\), is responsible for the characteristic odor of decaying fish. Draw a Lewis structure of methanamine.

Short answer

Methanamine's Lewis structure has carbon bonded to nitrogen and hydrogens, with lone pairs on nitrogen.

Step-by-step solution

Understanding the Basics

To draw the Lewis structure, identify the total number of valence electrons in methanamine. Carbon has 4 valence electrons, nitrogen has 5, and each hydrogen has 1 valence electron. So, methanamine (CH5N) has a total of 4 (from C) + 5 (from N) + 5×1 (from each H) = 14 valence electrons.

Sketching the Skeletal Structure

In methanamine, carbon (C) is usually the central atom because it can form four bonds. Connect the carbon atom to the nitrogen atom and arrange hydrogen atoms around them.

Placing Electrons Around Atoms

Distribute the 14 valence electrons starting by placing single bonds (2 electrons each) between C-H, C-N, and N-H to satisfy the hydrogen atoms' need for 2 electrons and achieve a stable configuration.

Completing Octet Rule

Ensure that carbon and nitrogen atoms have full valence shells. After placing single bonds, any remaining electrons should be placed on the nitrogen atom to complete its octet.

Final Verification

Check if all the atoms have fulfilled their valence requirements: Hydrogen should have 2 electrons in bonds, carbon should have 8 electrons around it, and nitrogen should also have 8 electrons surrounding it.

Key concepts

Methanamine

Methanamine, also known as methylamine, is a simple organic compound with the formula \( \text{CH}_5\text{N} \). It is notable for its presence in the unpleasant smell often associated with decaying fish. Understanding its structure is essential for grasping its role in various chemical reactions. Methanamine consists of a carbon atom bonded to a nitrogen atom and five hydrogen atoms. This molecule is a primary amine, meaning it has one alkyl or aryl group attached to the nitrogen atom. Methanamine is an important building block in organic synthesis, providing insight into basic chemical bonding and molecular interactions.

Recognizing methanamine's structure helps us identify how atoms connect and interact with each other. Its Lewis structure reveals the arrangement of electrons shared between atoms, which is a fundamental concept in chemistry.

Valence Electrons

Valence electrons play a crucial role in chemical bonding and are the electrons in the outermost shell of an atom. For methanamine, the main elements involved—carbon, nitrogen, and hydrogen—bring their own valence electrons to the table.

Here's the breakdown:

• Carbon has 4 valence electrons.
• Nitrogen has 5 valence electrons.
• Each hydrogen has 1 valence electron.

Together, these add up to 14 valence electrons for methanamine. These electrons are strategically arranged to form bonds between the atoms, ensuring that the molecules are stable.

When drawing the Lewis structure of methanamine, knowing the number of valence electrons is essential to correctly distribute them and create a valid representation of the molecule.

Octet Rule

The octet rule is a fundamental principle in chemistry, stating that atoms are most stable when they have eight electrons in their valence shell. This rule guides the formation of chemical bonds to achieve stability.

In methanamine, both carbon and nitrogen strive to fulfill the octet rule. Carbon naturally forms four bonds, achieving an octet with shared electrons. Nitrogen, with its tendency to form three bonds, also tries to reach an octet through bonding.

Hydrogen is an exception to the octet rule. It is stable with just two electrons as it only fills the first orbital. So, when drawing the Lewis structure for methanamine, ensuring that carbon and nitrogen meet the octet requirement, while hydrogen gets its duet, is critical for an accurate representation.

Chemical Bonding

Chemical bonding describes the attractive forces that hold atoms together in a molecule. In methanamine, these bonds include covalent bonds formed by shared pairs of valence electrons.

There are several types of bonds present:

• C-H bonds: Each hydrogen shares its single electron with carbon, forming a covalent bond.
• C-N bond: Here, carbon and nitrogen share electrons, connecting these atoms in the methanamine structure.
• N-H bonds: Similar to C-H bonds, electrons are shared between nitrogen and hydrogen.

Understanding these bonds helps in visualizing how atoms are arranged, reinforcing the concept that chemical bonding is the force that creates molecular structure. Methanamine's simple bonding allows students to see these principles in action, providing a stepping stone to more complex chemistry topics.