Classifying Matter

Section 2.1

Why do we classify?

• Classifying helps us understand the properties of a certain material

• Example: We separate laundry because fabrics react differently when they are washed a certain way.

How do we classify?

• Look at the composition and characteristics of materials and place them in separate categories.

Think of a way to classify the following items :

• Pencil

• Banana

• School Bus

• Fire engine

• Red marker

• Apple

How did you classify them?

• By color? (red and yellow)

• By function? (food, writing tool, or vehicles)

• We need to have a standard way to classify matter

• This helps us understand and remember physical and chemical properties

Matter

• Matter is anything that takes up space

• Matter can be classified in several different ways.

1. Solid, liquid, gas, or plasma

2. Metal, nonmetal, or metalloid

3. Acid, base, or salts

4. Elements, compounds, suspension, solution, colloid, or mixture

For this chapter, we are classifying into the last of those

four (Elements, compounds,

suspension, solution, colloid, or mixture)

Matter

Matter can be divided into two categories

• All matter is either a substance or a mixture

• Matter that always has the same composition is known as a pure substance (or just substance)

• Matter that has varying amounts of different things is known as a mixture

Matter

Substance Mixture

Substances can be divided into two categories

• Elements are substances that are pure and only have one type of atom– Examples: H, C, O, (anything found on the

periodic table of elements)

• Compounds are substances made from two or more different types of atoms– Examples: NaCl (salt), H2O (water), CO2

(carbon dioxide)

Matter

Substance Mixture

ElementCompound

Elements and Compounds can be further classified

• (You won’t be tested on this, because it isn’t in your book...but it might show up as a bonus question)

• Elements can either be metal, nonmetal, or metalloid

• Compounds can be organic (contain Carbon) or inorganic (don’t contain Carbon)

Matter

Substance Mixture

ElementCompound

Mixtures

• The properties of mixtures vary because the composition of a mixture is not fixed

• Example: Think of a chili recipe

Matter

Substance Mixture

ElementCompoundHeterogeneous

MixtureHomogeneous

Mixture

Mixtures can be classified into two groups

• All mixtures are either heterogeneous or homogeneous mixtures

• A heterogeneous mixture has parts that are noticeably different from one another

• A homogeneous mixture has multiple parts that are so evenly mixed, it is difficult to distinguish one substance from another.

Some heterogeneous mixtures can be classified as suspensions

• A suspension is a heterogeneous mixture that separates or layers over time

• These are things that would be easy to filter

• Example: Italian salad dressing

Matter

Substance Mixture

ElementCompoundHeterogeneous

MixtureHomogeneous

Mixture

Suspension Heterogeneous Mixture

Homogeneous Mixtures can be classified into two groups

• Colloids are homogeneous mixtures that have particles large enough to scatter light, but not enough to filter and separate

Example: Fog is a colloid

• Solutions are mixtures that form when substances dissolve and form a homogeneous mixture

Example: salt water

Matter

Substance Mixture

ElementCompoundHeterogeneous

MixtureHomogeneous

Mixture

Suspension Heterogeneous Mixture

Solution Colloid

End of notes for today

Flip your paper over and complete the flow chart on the

back

There are a series of questions you can ask yourself to figure out how to classify something

• To find out if it is a substance or a mixture ask this question:

Does it have a fixed and uniform composition? (Is it the same every time?)

• Yes – means it is a substance• No – means it is a mixture

Matter

Substance Mixture

If it is a substance:

• Now ask: Is there more than one type of atom?

• Yes – means it’s a compound

• No – means it’s an element

Matter

Substance Mixture

ElementCompound

Now, let’s pretend it does NOT have a fixed uniform composition…• Would it be a substance or a mixture?

• It would be a mixture!

• Now ask another question to see if it is homogeneous or heterogeneous

• Question: Are the substances noticeably different?– Yes : means it is a heterogeneous mixture– No: means it is a homogeneous mixture

Matter

Substance Mixture

ElementCompoundHeterogeneous

MixtureHomogeneous

Mixture

Let’s pretend it had noticeably different parts

• We need to determine if the heterogeneous mixture is a suspension or just a heterogeneous mixture

• Ask this Question: Do the particles layer or separate over time?

• Yes – means it is a suspension• No – means it is still just a heterogeneous

mixture

Matter

Substance Mixture

ElementCompoundHeterogeneous

MixtureHomogeneous

Mixture

Suspension Heterogeneous Mixture

Now, go back and pretend that the Mixture was NOT noticeably

different

• What is it?• It is a homogeneous mixture!

• Ask a question to classify it further: Can light clearly pass through it?

• Yes – means it is a solution

• No – means it is a colloid

Matter

Substance Mixture

ElementCompoundHeterogeneous

MixtureHomogeneous

Mixture

Suspension Heterogeneous Mixture

Solution Colloid

Use your flowchart to classify

• Sugar• Dirt• Carbon• Polluted water• Aluminum• Milk (this one is tricky)• Table salt (NaCl)• Pizza

• Italian salad dressing• Air• Hydrogen

Use your flowchart to classify1. Copper2. Lemonade3. Smoke4. Ice cream sundae5. Helium6. Hydrogen Peroxide (H2O2)7. Sugar Water8. Blue Gatorade9. Beach sand10.Ethanol (C2H5OH )11.Garden Salad12.Muddy water13.Silicon14.Gasoline floating on top of a puddle