Chemists use a classification system to describe the stuff around us. The classification system first categorizes a sample of stuff as being composed of a single pure substance or of a mixture of two or more substances. Pure substances can either be composed of elements (like the 118 that currently make up the Periodic Table) or of compounds. And mixtures of substances can be composed of elements, compounds, or both elements and compounds. These components or parts of a mixture could be homogeneous (the same throughout) or separated into distinctly different regions or layers and referred to as a heterogeneous mixture.
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Classification of Matter - help3
There are two very similar versions of questions in this Question Group. Here is one of the versions.
Version 1:
Consider ketchup and pepperoni pizza. Consider what each must be composed of. Then identify each according to its class.
Pure substance
Homogeneous mixture
Heterogeneous mixture
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.
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.
