Unit 1 Lesson 4 Pure Substances and Mixtures

Essential Question: How do pure substances and

mixtures compare?

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Big Idea: Matter is descried by its properties and

may undergo changes

A Great CombinationHow can matter be classified?

• Matter is made up of basic “ingredients” known as atoms.

• An atom is the smallest unit of an element that maintains the properties of that element.

• Substances are classified as elements, compounds, and mixtures.

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Substances are classified as:

Basic ingredients of all

“stuff”Matter

Elements Compounds Mixtures

#5) Compare

Elements,

compounds

and mixtures

are all made

up of atoms

How can matter be classified?

• An atom is a building block of matter

• An element is made of only one kind of atom.

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•A compound is made up of different kinds of atoms that are chemically combined.

•A mixture contains a variety of elements and compounds that are not chemically combined.

Air

How can matter be classified?

• Is water an element, a compound, or a mixture?

Unit 1 Lesson 4 Pure Substances and Mixtures

Visualize it #7

2 different colors represent 2 different types of atoms

compound

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Pure GeniusWhat are pure substances?

• A pure substance is a substance with definite physical and chemical properties.

• Pure substances are made up of just one type of particle. • Element and Compounds are Pure substances

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The atoms that

make up copper

are all the same

Water molecules are made up of two

different types of atoms that are joined

together. The molecules that make up

water are all the same

Pure GeniusWhat are pure substances?

• Physical changes such as melting, freezing, cutting, or smashing do not change the identity of pure substances.

• When a pure substance undergoes a chemical change, it is no longer that same substance.

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The Chemical bonds that hold the

atoms together are broken.

A new substance is formed.

Unit 1 Lesson 4 Pure Substances and Mixtures

Pure

Substance

Made of

atoms

Classified InformationHow can elements be classified?

• Elements are classified as metals, nonmetals, or metalloids.

• Classifying elements helps scientists predict the properties of elements.

• The periodic table is a tool used to classify and identify elements that have similar properties.

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How can compounds be classified?

• Compounds can be classified as acidic, basic, or neutral by measuring pH.

• Pure water (Neutral) has a pH of 7 • Acids have a pH below 7. • Blue litmus paper turns red in the presence of an acid. • Bases have a pH above 7.• Red litmus paper turns blue in the presence of a base.

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- Describing Acids and Bases

Properties of Acids and Bases

Litmus is an example of an indicator, a

compound that changes color when in

contact with an acid or a base.

Online Activity

How can compounds be classified?

• Compounds can be organic or inorganic.

• Organic compounds are those that contain carbon and hydrogen.

• Organic compounds made by living things are called biochemicals.

• Carbohydrates, lipids, proteins, and nucleic acids are biochemical compounds.

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Mix and Match What are mixtures?

• A mixture is a combination of two or more substances that are combined physically but not chemically.

• Mixtures are not pure substances and do not have definite properties.

• Substances within a mixture keep their identities and individual properties.

• Mixtures can be separated by physical changes, although some mixtures are difficult to separate.

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•Magnets, centrifuges, filters, and other materials can be used to separate mixtures.

15) Devise

Pick out the rocks by hand. Sort by size

14) Visualize

A) Sand and salt are poured

into a single beaker. The result is a mixture because

B) When water is added to the

sand-salt mixture,

C) When the liquid is poured

through a filter,

D) The remaining salt

water is heated until

They are not

chemically

combined

Salt dissolves

in water. Sand

does not.

(solubility)

Salt water

passes

through the

filter

Water is

boiled off

(evaporated)

leaving salt

behind

Unit 1 Lesson 4 Pure Substances and Mixtures

Simple Solution

How can mixtures be classified?

• A homogeneousmixture has the samecomposition throughout.

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•A heterogeneousmixture is one that does not have a uniform composition.

heterogeneous homogeneous

How can mixtures be classified?

• A suspension is a heterogeneousmixture.

• Particles in a suspension are spread throughout a liquid or gas, but are too large to stay mixed unless shaken or stirred.

• Particles settle in suspensions.• A solution is a homogeneous mixture in

which one substance is dissolved in another substance.

• Colloids have particles that are unevenly spread throughout the mixture. (looks homogenous but really heterogeneous)

• particles in colloids are too small to settle out of the mixture.

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A substance that has

definite physical and

chemical properties.

Mixture

Compound Heterogeneous

Solution

2 or more atoms

chemically

combined

Same

throughout

(Uniform)

Between

solution and

suspension

One substance

dissolved in

another

Matter

Pure Substances

Elements

Metals

Nonmetals

Metalloids

Compounds

pH

Acid

<7

Blue litmus turns red

Base

>7

Red litmus turns blue

Organic or inorganic

Role in the body

Biochemicals

Carbohydrates

Lipids

Proteins

Nucleic acids

Mixtures

Heterogeneous

Suspensions

Particles are spread

throughout

too large to stay mixed

unless shaken or

stirred

Particles settle

Colloids

particles that are unevenly spread

throughout

particles in colloids are too small to settle out of the mixture

Homogenous

Solutions

one substance is dissolved in

another substance