Stuff ... the things around us ... more technically referred to as matter, is made of atoms. But when you are looking at such stuff, there may be just a single type of atom in it - like copper atoms. A copper wire is a pure substance made of the element copper.
Or the stuff could be composed of groups of atoms of different types bound together to form a compound such as water ... which we chemists (in our nerdier moments) call dihydrogen monoxide.
Or the stuff around you could be composed of a mixture of elements or a mixture of compounds or even a mixture of both elements and compounds. This is the case for the air around you. Air is a mixture of several gases, like nitrogen gas and oxygen gas and other gases that are present at smaller percentages.
When we think about stuff from a chemical perspective, one of the first questions we chemists ask is ... What is this sample of matter made of? And when we ask that question, we typically use a system of classification that is described in the graphic below. Study the graphic and use it to answer this question.
