What does molecular weight represent?

Molecular weight represents the sum of the atomic weights of the individual atoms that make up a molecule. This concept is fundamental in chemistry because it allows for the calculation of how much of a substance is present in a sample. Each element has a specific atomic weight, which can be found on the periodic table. When calculating the molecular weight of a compound, you take into account the number of each type of atom in the molecule and sum their weights accordingly.

For example, in a water molecule (H₂O), you would calculate the molecular weight by adding the atomic weights of two hydrogen atoms and one oxygen atom. This gives a precise idea of the mass of one molecule of water, which can then be used for various chemical calculations, such as determining how many molecules are in a given mass of water.

The other options do not accurately define molecular weight, as they pertain to different concepts in chemistry or measurements that do not provide the comprehensive view of molecular composition that molecular weight does.