A student carefully placed 18.5 g of sodium in a reactor supplied with an excess quantity of chlorine gas. When the reaction was complete, the student obtained 36.8 g of sodium chloride. How many grams of chlorine gas reacted?

An atom is a particle of matter that uniquely defines achemical element. An atom consists of a central nucleus that is usually surrounded by one or more electrons. Each electron is negatively charged. The nucleus is positively charged, and contains one or more relatively heavy particles known as protons and neutrons.