The ball-and-stick molecular model is a representation of caf-feine. Calculate the molecular weight of caffeine. (Gray = C, red = O, blue = N, ivory = H.) (LO 3.3)

(a) 194.2 (b) 182.2 (c) 192.2 (d) 180.2

Key Concepts

Molecular Weight

Molecular weight, or molar mass, is the sum of the atomic weights of all atoms in a molecule, expressed in grams per mole (g/mol). It is calculated by multiplying the number of each type of atom by its atomic weight and summing these values. For caffeine, which contains carbon, hydrogen, nitrogen, and oxygen, the molecular weight is essential for understanding its chemical properties and behavior.

Ball-and-Stick Model

The ball-and-stick model is a three-dimensional representation of molecular structures, where balls represent atoms and sticks represent the bonds between them. This model helps visualize the arrangement of atoms in a molecule, including bond angles and distances. In the case of caffeine, the model illustrates the connectivity and spatial orientation of carbon, hydrogen, nitrogen, and oxygen atoms.

Chemical Composition of Caffeine

Caffeine is an organic compound with the chemical formula C8H10N4O2, indicating it contains 8 carbon (C), 10 hydrogen (H), 4 nitrogen (N), and 2 oxygen (O) atoms. Understanding its chemical composition is crucial for calculating its molecular weight and for studying its biological effects and interactions. Each atom type contributes differently to the overall molecular weight, influencing its properties.