MATTER; CHAPTER 3

Elements, Compounds, Mixtures

DEMO…

Place a black dot on the line drawn in pencil on your filter paper and place it in the beaker that has some water in the bottom.

Make sure the dot is not under water.

Watch as we take notes. What do you see?

ALL matter can be classified into 1 of 3 groups:

ElementsCompounds

Mixtures

ELEMENTS:Simplest Pure substance

Made of ONE type of atom

Unique properties to identify

92 naturally occurring

Organized on Periodic table with chemical symbols

3 main types…

Could you identify these elements by their density?

Could you identify these elements by their conductivity?

Could you identify these elements by their reactivity to oxygen?

Could you identify these elements by their melting point?

Cobalt Iron Nickel

Melting Point:

1,495 oC 1,535 oC 1,455 oC

Density: 8.9 g/cm3 7.9 g/cm3 8.9 g/cm3

Conductivity

Electric current and thermal energy

Electric current and thermal energy

Electric current and thermal energy

Reactivity with oxygen

Unreactive Slowly forms rust

Unreactive

So…..Can you identify elements by 1

property? Why or why not?

Cobalt Iron Nickel

Melting Point:

1,495 oC 1,535 oC 1,455 oC

Density: 8.9 g/cm3 7.9 g/cm3 8.9 g/cm3

Conductivity

Electric current and thermal energy

Electric current and thermal energy

Electric current and thermal energy

Reactivity with oxygen

Unreactive Slowly forms rust

Unreactive

1. Metals:

Shiny; good conductors, malleable, ductile

2. Nonmetals:

Dull; poor conductors, brittle

3. Metalloids:

Semiconductors; Properties of both metals and nonmetals

1. What is an element?

2. Create a word web that shows connections between the following:

ElementsMetals

MetalloidsNonmetals

3. Describe these connections

Warm up

Elements

Metalloids

NonmetalsMetals

Math and Science…The human body is made of the following elements:

Oxygen; 64.6%Carbon; 18.0%Hydrogen; 10.0%Nitrogen; 3.1%Calcium; 1.9%Phosphorous; 1.1%Other; 1.3%

This type of data would best be displayed using ______________ graph.Create one.

Math and Science…

Percentages of Elements in the Human Body

65%18%

10%

3%

2%

1%

1%

Oxygen

Carbon

Hydrogen

Nitrogen

Calcium

Phosphorous

Other

HOW SMALL IS AN ATOM?

(Don’t memorize these numbers!)An aluminum atom has a diameter of about

______________cm.

A A piece of aluminum foil is about _________________atoms thick.

0.00000003

50,000

WHAT’S INSIDE AN ATOM?

Particle Charge Location Mass

Proton

Neutron

Electron

Positive

Neutral (0)

Negligible

1/1836 amu

Electron Clouds

Nucleus 1 amu

1 amuNucleus

Negative

Copy this chart in your notes and use pages 87-91 to fill it in.

ATOMS AND THE PERIODIC TABLE

Use the periodic table on page 158 to find sulfur and copy its square exactly in your notes.

Use the key on page 158 to label each of the four pieces of information found in this square.

 

16

SSulfur

32.1

Atomic Number

Chemical Symbol

Element Name

Atomic Mass

1. Describe the 3 “classes” that elements can be grouped into?

2. What is the smallest part of an element?

HOW ARE ELEMENTS DIFFERENT?

Look at all of the different kinds of elements on the periodic table.

If all protons are identical, all neutrons are

identical, and all electrons are identical, how do we have such a variety of atoms?

It depends on the _______________________!PROTON NUMBER

1. What is an element?2.What is a compound?3.How are elements and

compounds similar? Different?

THE NUMBER RULES!

All elements have a model that can be drawn to show how their Protons, Neutrons, and Electrons are arranged. Look at Nitrogen shown below:

7p+

7n

7e-

COMPOUNDS:2 + elements chemically combined

Elements react with each other

Most substances on Earth

Different properties than original elements

Molecules with more than 1 type of atom

Chemical formulas

CH4H2O

CH4

??? What is happening to the magnesium ribbon?

EX:

Magnesium + Oxygen Magnesium Oxide

BOHR MODELS…Represent compounds

Ex: H2O (water)

1 P

0 N

1 P

0 N

8 P

8 N

Can be separated by chemical reactions

Flame TestsCopy the chart in your notes:

Compound Flame Color

Calcium chloride

Potassium chloride

Sodium chloride

Barium chloride

Lithium chloride

Strontium chloride

Copper chloride

Flame Tests

Is this a chemical or a physical change? Why?

Do you think the flame colors are caused by the chloride or the metals? Why?

What color do you think sodium fluoride would have? Why?

Warm up1. What is happening to the

compounds in the soda?2. What is a compound?3. List 3 examples of

compounds you are familiar with.

Electrolysis…Uses electric currentSeparates water into H and OUsed to obtain aluminum, copper, peroxide

Electrolysis…Was this a chemical or physical change? How do you know?What type of matter is water (element, compound, mixture) ?

1. How are compounds and elements alike?

2. How are compounds and elements different?

3. What are 2 ways to break down a compound?

MIXTURES:

2 + substances; NOT chemically combined

NO chemical change

Identities of parts DO NOT change

Physically separate parts

TYPES…

Homogeneous: looks like one substance

Heterogeneous: different substances visible

H2O water

NaCl salt

The Liberty Bell is a mixture of:

70% copper

25% tin

Small amounts of lead, zinc, arsenic, gold & silver

Demo…Look at the mixture at your

desk and figure out which one you have.

See if the substance is homogeneous or heterogeneous.

Complete your chart. Share your data with the class.

Mixture ID

Mixture Homogeneous or

Heterogeneous?

How To Separate?

A

B

C

D

E

F

G

H

I

Mixture Names

Sand and iron filings

Saltwater

Nuts and bolts

Soft drink (gas in liquid)

Saltwater and sand

Air

Coffee grounds and water

Blood

Steel (C + other elements in iron)

1. Describe your observations of the flame tests. Was this chemical or physical change?

2.Describe your observations of the electrolysis experiment? Was this chemical or physical change?

1. Compare and contrast compounds and mixtures.

2.What is the difference between homogeneous and heterogeneous mixtures?

SOLUTIONS:

Looks like 1 substance

Really 2 + substances evenly distributed

Read page 76 in your textbook. Why is perfume a solution?

Demo…

What do you notice about the different beakers of colored water?

How would you describe them?

Solute: substance that is dissolved

Solvent: substance that does the dissolving

Water is the Universal Solvent

WARM UPRetrieve your paper slip with the marker streak. We completed these a few days back.

1. Discuss and list some QUALITATIVE observations about this paper.

2. What type of substance was the marker? (element, compound, mixture, etc.)

3. Use your science terms to support your answer to number 2.

EXTENSIONChromatography

Can be used for many things…

Forensic analysis

Determine Unknown chemicals

A TASTY SOLUTION…Group Members 1 & 4: allow the candy to completely dissolve without any help

Group Member 2: Allow the candy to dissolve with only your tongue moving it around

Group Member 3: Allow the candy to dissolve with both tongue and teeth

***All members record time for shell to dissolve

A TASTY SOLUTION…In your solutions…

1. What was the solvent?

2. What was the solute?

3. What was the difference in dissolving rate for the different members?

4. What things can be done to change the dissolving rate of a substance?

Solubility is how much can dissolve

Changes with conditions

Amount of solute is called concentration

Solubility of various substances at increasing temperatures

1. What is the independent variable? The dependent?2. Which substance is more soluble at lower temps than at higher?3. Which substance does not change its solubility much?

Why does a can of soda get “flat” when it sits open at room temperature?

When Temp Solubility of gas

Why can Mrs. Lock dissolve more ice tea mix when she boils the water first?

When Temp Solubility of solids

SUSPENSIONS:

A mixture;

Particles are dispersed and visible but may settle out

Can be separated by filtration

WARM UP1. Why are

suspensions considered mixtures?

2. Why is a snow globe a good example of a suspension?

WARM UP1. What are the

properties of a solution?

2. What are the properties of a suspension?

COLLOIDS:Properties of solutions and suspensions

Small particles Mixed well; don’t settle out; scatter light

Can’t be separated by filtration

Types of mixtures…

Demo…

Is this a colloid? Why?

Why is this a colloid?

Why is this a colloid?

Type Homogeneous or Heterogeneous

1. Oil and water

2. Chicken broth

3. Milk

4. Granite (rock)

5. Soda (gas in liquid)

6. Salt water

7. Raisin bran

8. Toothpaste

9. Sand and water

10. Oil and vinegar

11. Mayonnaise

12. Kibble and Bits

Solution, Colloid, Suspension

WARM UP…

1.Take out your textbook and uncover it

2.Clean any papers out of the book-recycle them!

3.Get out a PENCIL for the test