Give molecular formulas corresponding to each of the following ball-and-stick molecular representations (red = O, gray = C, blue = N, ivory = H). In writing the formula, list the elements in alphabetical order. (a) Alanine (an amino acid)

Key Concepts

Amino Acids

Amino acids are organic compounds that serve as the building blocks of proteins. Each amino acid contains a central carbon atom, an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable side chain (R group) that determines the specific properties of the amino acid. Alanine, for example, has a simple side chain consisting of a methyl group (-CH3).

Molecular Formulas

A molecular formula represents the number and types of atoms in a molecule, indicating the composition of the substance. It is written by listing the chemical symbols of the elements present, followed by subscripts that denote the number of each type of atom. For example, the molecular formula for alanine is C3H7NO2, which shows it contains three carbon atoms, seven hydrogen atoms, one nitrogen atom, and two oxygen atoms.

Ball-and-Stick Model

A ball-and-stick model is a three-dimensional representation of a molecule, where balls represent atoms and sticks represent the bonds between them. This model helps visualize the spatial arrangement of atoms in a molecule, which is crucial for understanding molecular geometry and reactivity. In the case of alanine, the model would illustrate the connectivity and arrangement of carbon, hydrogen, nitrogen, and oxygen atoms.