Heptane and its isomers have a formula of \(\mathrm{C}_{7} \mathrm{H}_{16}\) and a molecular ion of \(m / z=100\). Determine the formula of an organic molecule containing C, \(\mathrm{H}\), and \(\mathrm{O}\) for which \(\mathrm{m} / \mathrm{z}=100\). Determine the formula of an organic molecule containing \(\mathrm{C}, \mathrm{H}\), and \(\mathrm{N}\) for which \(\mathrm{m} / \mathrm{z}=100\). Draw two isomers of each of your answers.

In mass spectrometry, understanding the concept of a molecular ion is crucial. A molecular ion is essentially a molecule that has lost or gained an electron, resulting in a positively or negatively charged ion. This ion is represented as M+. The mass-to-charge ratio (m/z) of the molecular ion typically corresponds to the molecular mass of the compound. For instance, in our problem, the molecular ion (m/z) is 100, which indicates that the molar mass of the organic molecule is 100 g/mol. This information helps us determine the possible molecular formulas by summing up the atomic masses of the constituent elements like Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N).

Isomers are molecules that have the same molecular formula but different structural arrangements. These different arrangements can lead to distinct physical and chemical properties despite having the same constituent atoms. Taking the example of heptane and its isomers, all of them share the same formula, \(\text{C}_{7}\text{H}_{16}\). However, these can be arranged in various configurations, such as straight chains or branched forms, leading to different isomers.
When considering organic molecules with the formula \(\text{C}_{6}\text{H}_{12}\text{O}\), isomers like hexanol and cyclohexanol are common. Both have the same number and types of atoms, yet their shapes are different. The same applies to molecules with the formula \(\text{C}_{6}\text{H}_{12}\text{N}_{2}\). Examples include hexanediamine and piperazine. Understanding isomers is key when predicting the properties and behaviors of organic compounds.

Molecular mass is the sum of the atomic masses of all the atoms in a molecule. For organic molecules, it's crucial to use the periodic table to determine the individual atomic masses and then add them according to the molecular formula. For example, Carbon (C) has an atomic mass of 12 g/mol, Hydrogen (H) is 1 g/mol, Nitrogen (N) is 14 g/mol, and Oxygen (O) is 16 g/mol.
In our problem, the molecular mass of the organic molecule is given to be 100 g/mol. Thus, for \(\text{C}_{6}\text{H}_{12}\text{O}\), we calculate it as follows: \ (6 \times 12) + (12 \times 1) + (1 \times 16) = 100 \. Similarly, for \(\text{C}_{6}\text{H}_{12}\text{N}_{2}\), the calculation is: \ (6 \times 12) + (12 \times 1) + (2 \times 14) = 100 \. This helps us confirm that the molecular mass aligns with the given m/z value, guiding us to the correct molecular formula.