The atomic mass in Phosphorus is a decimal because . Neutrons aren't always the same mass. It is charged. proton number varies. It is the average mass of all phosphorus elements in nature.

Which of the following describes a compound? (hint: carbon and oxygen bo a. a piece of pure carbon, containing only carbon atoms b. oxygen gas surrounding a solid piece of carbon c. a substance made of two oxygen atoms for each carbon atom carbon and oxygen atoms mixed without being bonded together