Question

1-64 assign each of the following molecular descriptions for a pure substance to the categories (1) must be an element, (2) must be a compound, or (3) could be an element or a compound. a. molecules contain three kinds of atoms. b. molecules are homoatomic. c. molecules are tetraatomic. d. molecules are both heteroatomic and triatomic.

Explanation:

Part a

Step1: Recall element/compound definitions

An element has only one type of atom; a compound has two or more. Molecules with three atom types can't be elements (need one type), so must be a compound.

Step1: Define homoatomic molecules

Homoatomic molecules have only one type of atom (e.g., \(O_2\), \(N_2\)). Elements can exist as homoatomic molecules; compounds need multiple atom types. So homoatomic molecules must be elements.

Step1: Analyze tetraatomic molecules

Tetraatomic means 4 atoms per molecule. They could be homoatomic (e.g., \(P_4\), an element) or heteroatomic (e.g., \(NH_3\), a compound). So it could be either.

Answer:

(2) must be a compound

Part b