Question

chapter 3 hw
3.1 classify each of the following pure substances as an element or a compound:
a. a silicon (si) chip
b. hydrogen peroxide (h₂o₂)
c. oxygen gas (o₂)
d. rust (fe₂o₃)
e. methane (ch₄) in natural gas

Explanation:

Step1: Recall element - compound definition

An element is a pure substance made of only one type of atom. A compound is a pure substance made of two or more different types of atoms chemically combined.

Step2: Analyze silicon (Si) chip

Silicon is made of only silicon atoms. So it is an element.

Step3: Analyze hydrogen peroxide ($H_2O_2$)

It is made of hydrogen and oxygen atoms chemically combined. So it is a compound.

Step4: Analyze oxygen gas ($O_2$)

It is made of only oxygen atoms. So it is an element.

Step5: Analyze rust ($Fe_2O_3$)

It is made of iron and oxygen atoms chemically combined. So it is a compound.

Step6: Analyze methane ($CH_4$)

It is made of carbon and hydrogen atoms chemically combined. So it is a compound.

Answer:

a. Element
b. Compound
c. Element
d. Compound
e. Compound