Matter is anything that has mass and occupies space. The concept marks off the physical substances chemistry studies from things that are not matter, such as light or heat. A book, a sample of water, and the air in a room are all matter, whereas a beam of light is not.

物质是凡是具有质量并占据空间的东西。这一概念把化学所研究的实体物质与并非物质的事物(如光或热)区分开来。一本书、一份水样和房间里的空气都是物质,而一束光则不是。