Lesson 10

(1) Element or Compound

Obj. 1.  From the name of a chemical, determine whether it is an element or compound.

The first objective says that from the name of the chemical you should be able to determine whether it is an element or a compound. Doing that essentially involves recognizing the names of the elements, and then if you are dealing with something that combines more than one elements, then you are dealing with a compound. We will not be dealing with alloys in this particular lesson.

Exercises

Which of the following chemicals are elements and which are compounds?

a. water
b. ammonia
c. oxygen
d. sulfur
e. carbon dioxide
f. copper(II) sulfate
g. ferrous oxide

Worked-Out Examples (a,b,c)

(a) Water:  Water is one of those things that you should just recognize by name and  recognize that it consists of hydrogen and oxygen and therefore water is a compound.

(b) Ammonia:  Ammonia also is a name of a chemical which is a compound that you should recognize, rather than analyze. Ammonia consists of nitrogen and hydrogen; its formula is NH₃. So, ammonia is a compound.

(c) Oxygen:  Oxygen you should recognize as an element, not as a compound.

With those three worked out as examples, try doing the rest of exercise 1. When you have completed that, check your answers below.

Answers to Exercises

Which of the following chemicals are elements and which are compounds?

a. water - compound
b. ammonia - compound
c. oxygen - element
d. sulfur - element
e. carbon dioxide - compound
f. copper(II) sulfate - compound
g. ferrous oxide - compound

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E-mail instructor: Eden Francis

Clackamas Community College
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