ChemistryThe Science of Matter

Upward Bound Program Summer 2012

What is Chemistry?It is the study of the composition of matter and the changes that matter undergoes.

Do NowList at least 5 chemicals that you are familiar with from past experience.

ChemistryThe science that investigates the structure and properties of matter

Matter: anything that takes up space and has mass

Mass: the measure of the amount of matter that an object containsNOT Matter-

HeatLightRadio waves etc.

Matter continuedStructure: refers to what it is made of and of how it is organized

Properties: Describe the characteristics and behavior of matter including the changes it undergoes

Behavior of MatterDetermined by BOTH

The elements it containsArrangement of those elements

Example Salt vs.

Water

Sodium and Chloride Hydrogen and Oxygen

Contain different elements --- Have different properties!

ExampleAspirin Vs Table Sugar

Both contain only Carbon, Hydrogen and Oxygen molecules --- same composition Different Structures Cause Different Behaviors!

Identifying PropertiesMany are easy to observe by simple tests

Use heat, magnets, electricity etcColorState: solid, liquid or gas at room temp and pressureSoft or hardDoes it burn?Does it dissolve in water?

These are from a macroscopic perspectiveThings you can touch, taste, feel, smell and see

Physical change vs. Chemical change

Physical Change Chemical ChangeDoesn't change what the substance is.

A new substance is formed and energy is either given off or absorbed.

Can be reversed Cannot be reversed with the substance changed back without extraordinary means, if at all.

ExamplesPhysical Change Chemical ChangePaper cut into pieces, small pieces are still paper

Paper burned is no longer paper

Dissolve sugar in water Make a cake with flour, water, sugar and other ingredients and bake them, it would take extraordinary means to separate the various ingredients out to their original form.

Physical Vs. Chemical Change Worksheet (10-15 minutes)

In groups complete the given handout

You may use your notes

Be sure that you are prepared to share your answers with the class

Share Answers (3 min/group)

Be sure to explain why you chose your answer.

Each table shares their answers with the class.

ALL STUDENTS MUST RECORD THE CORRECT ANSWER ON THEIR HANDOUT!

Homework

Classifying Matter1. Substance: matter with constant

compositiona) Element: Made of only one type of atomb) Compound: 2 or more elements that are

chemically combined

2. Mixture: Matter with variable composition

a) Heterogeneous Mixture: Made up of more than 1 phase

b) Homogeneous Mixture: also called solutions, made up of only 1 phase

MixturesA material that is made of 2 or more things which are not combined chemically

Each of the parts still keep their own identities

Made by blending, but NOT forming chemical bonds or chemical change!

Most everyday matter occurs as mixtures

Heterogeneous and Homogeneous Mixtures

A classification of matter based on composition

Homogeneous mixture: no clumping or grouping but rather a uniform dispersal of the material it is made of.

Ex. Air; made of N2, O2, CO2 and other gasesA liquid in which there is a solvent and a solute is called a solution

Heterogeneous mixture: it is easy to identify all if the different components

Homogeneous Mixtures

REMEMBER Mixtures

Are made of 2 or more things which are not combined chemically

Each of the parts still keep their own identities

Made by blending, but NOT forming chemical bonds or chemical change!

Most everyday matter occurs as mixtures

Separating MixturesMixtures can be separated

through a physical process, (the identity of the substance remains unchanged).

Using their Physical propertiesBringing about physical changes to separate the mixture into its components (different substances it is made of)

Making a Mixture

AND

SAND SUGAR

The Mixture

How can we separate it?

What do you think?Work with your lab partner to come up with a suggested method. (10 minutes)You may use your class notes, but your brain is your best asset.Write your thoughts in your notebooks.Do not be afraid to try!

Report out on ideas

So, what did you come up with?

Share your thoughts! (10 minutes)

What can we do?Method #1•Use a pair of tweezers and a microscope to physically separate the particles•Requires a lot of time and patience

Method #2Step #1•Recall the properties of water and of sand

•Sugar dissolves in water•Sand does NOT•Use the

difference!

Step #2•Recall the properties

again•sand will not pass through a filter•Sugar and water solution will•Use the

difference!

Step #3• Recall the

properties of sugar and

water•sugar will not evaporate (change state) at 100 degrees Celsius•water will !• Use the difference!

Step #4

You have the two pure substances

again!Sand in the filter!Sugar in the bottom of the beaker!

Lab TomorrowSeparating Mixtures

REMEMBER: Physical Properties1. Density: Mass per unit volume2. Solubility in water : Does it dissolve in

water?3. State of mater: at room temp and pressure4. Transparency: lets light pass through 5. Boiling point: Temperature at which a

substance goes from liquid to gas6. Melting point: Temperature at which a

substance goes from solid to a liquid7. Brittleness: Tendency to crack or break8. Ductility: Ability to bend without breaking9. Elasticity: Ability to be stretched or

compressed then return to original size

Chemical propertiesChemical Property• Flammability: The ability to burn• Ability to rust: Reacts with oxygen to produce

rust• Reactivity with vinegar: Reacts with vinegar

to produce new substances

Solutions (homogeneous)

Air (gas)

Martini (liquid)

Salt water (liquid)

Plastic (solid)

SubstancesHomogeneous materials that contain only 1 kind of matter

Have definite composition and properties

Substances which can not be broken down into a simpler substance is an ELEMENT.

Substances which can be broken down into a simpler substance is a COMPOUND.

They are made of 2 or more elements

ElementsMade of only one kind of atom

Can not be made simplified by physical or chemical means

Can exist as atoms (carbon) or molecules (N2)

CompoundsConsist of 2 or more DIFFERENT atoms bound together (H2O)

Can be broken down into smaller types of matter by chemical means only.

Have properties which are different than the elements they are made of

Always contain the same ratio of its components atoms ( ex 2 hydrogen's to 1 oxygen, in water)

Elements, Compounds,

MixturesSodium is an element.Chlorine is an element.When sodium and chlorine bond they make the compound sodium chloride, commonly known as table salt.

Compounds have different properties than the elements that make them up.Table salt has different properties than sodium, an explosive metal, and chlorine, a poisonous gas.

Classify the Following1. Ocean water-

2. Calcium-

3. Vitamin C-

4. Dry ice –

5. Copper-

6. Grain alcohol-

7. after shave lotion-

8. Hamburger-

9. Al foil –

10. Milk-

11. Salt-

12. Iron nail-

Answers 1. Ocean water- solution

2. Calcium- element

3. Vitamin C- Compound ( L-asorbic acid)

4. Dry ice – compound (CO2)

5. Copper- element

6. Grain alcohol- compound (C2H5OH)

7. after shave lotion- heterogenous mixture

8. Hamburger- hetero

9. Al foil – element

10. Milk- solution

11. Salt- cmpd

12. Iron nail- element