Question

lesson 6
what is a polymer?
exists as either pure substances or mixtures.
a pure substance, as the name suggests, consists of only __ type of matter. a pure substance can be either an or a __.
are all elements pure substances? are all molecules pure substances? why or why not?

Explanation:

To solve the fill - in - the - blanks related to pure substances in chemistry (a sub - field of Natural Science):

Step 1: Analyze the first blank about the type of matter in a pure substance

A pure substance, by definition, consists of only one type of matter. So the first blank should be filled with "one".

Step 2: Analyze the second and third blanks about the classification of pure substances

A pure substance can be either an element or a compound. Elements are made up of only one type of atom, and compounds are made up of two or more different types of atoms chemically combined in a fixed ratio. So the second blank is "element" and the third blank is "compound".

Step 3: Answer the questions about elements, molecules and pure substances

• Are all elements pure substances?

Yes. An element is a pure substance because it is made up of only one type of atom. For example, oxygen ($O_2$) is an element and it is a pure substance as it contains only oxygen atoms.

• Are all molecules pure substances?

No. While many molecules are part of pure substances (like $H_2O$ in pure water), there are cases where molecules can be part of mixtures. For example, in a mixture of water ($H_2O$) and ethanol ($C_2H_5OH$), both are molecules but the overall system is a mixture, not a pure substance. Also, some substances like ozone ($O_3$) and oxygen ($O_2$) can form a mixture (ozone - oxygen mixture) where both are molecules but the combination is a mixture. Another example is a mixture of different isotopic molecules (e.g., a mixture of $^{16}O_2$ and $^{18}O_2$), these are molecules but the mixture is not a pure substance.

Answer:

s for the blanks:

1. The first blank: $\boldsymbol{one}$
2. The second blank: $\boldsymbol{element}$
3. The third blank: $\boldsymbol{compound}$