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Page 1: 1B.  Looking at Water & Its Contaminants

1B. Looking at Water & 1B. Looking at Water & Its ContaminantsIts Contaminants

Learning more about the chemistry of water and how substances interact with water

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Do Now:

The teacher has two substances on the desk (A and B). Are they the same? Venture a guess as to what you think they are.

Explain why beetles have the ability to walk on water. (Take a look at the picture below)

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Objectives:Objectives:

SWBAT: Learn the physical properties of water

& compare to another liquid. Use a balance Read a grad. cylinder Make and record measurements Record observations

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Water has Physical PropertiesWater has Physical Properties

Matter can be distinguished by its properties.

Physical properties are those that can be observed and measured without changing the chemical makeup of the substance

Can you think of some? Write down at least 3 physical

properties of water that you can think of.

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Physical Properties of water:

Color – colorless, clear Odor - odorless Density = mass/ volume

Temperature dependent Freezing point = 0°C Boiling point = 100°C Surface tension

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““Pure” WaterPure” Water

“Pure” water is water with absolutely nothing else dissolved or suspended in it

Properties of pure waterClearColorlessOdorlessTasteless

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Lab Demo

Make and record proper observations for each demonstration.

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Do Now

Draw a graduated cylinder, with the appropriate volume markings and layer the liquids according to density. 5 mL liquid A, Density = 3.4g/ml 2 ml liquid B, Density = 0.90/ml 3 ml liquid C, Density = 1.00g/ml

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Do Now

What physical property of water explains the “sheeting action” under the swimmers right arm?

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Objectives

SWBAT compare and contrast surface tension between water and alcohol

SWBAT define matter and discuss the physical properties of water.

SWBAT calculate density

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Surface Tension

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Surface Tension: Forces of attraction between the

hydrogen atoms in water that keep the atoms close together

Almost as if they form a barrier and make the water molecules “stick” together

Held together by cohesive forces. Responsible for creating a meniscus Responsible for “spherical” water drops Doesn’t stick to wax (on cars etc.)Adheres

weakly, so molecules stick together.

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Molecular view of surface tension

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HW

Pg 50 (1-4)

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Do Now

Draw: A) a water molecule (H2O)

B) 2H2O

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Objectives

SWBAT identity the number of different compounds in a substance or mixture

SWBAT draw different mixtures and answer questions related to those pictures

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Particulate LevelParticulate Level

To understand the macroscopic (large scale & readily observed) properties of water, you have to understand water’s behavior at the particulate level – the level of small particles – the level of atoms and molecules

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SubstancesSubstances

Atoms – “building blocks of matter”

Elements – made of one kind of atom

Represented by symbols (H, O, Ne) & sometimes formulas (H2, O2)

Molecules – made of atoms joined together – atoms can be the same or different

Compounds – made of different elements combined together

Represented by formulas (H2O, KCl)

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MODELS:MODELS:REPRESENTATIONS OF ATOMS & REPRESENTATIONS OF ATOMS & MOLECULESMOLECULES

These pictures are one kind of model (space filling model).

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Drawing ModelsDrawing Models

Sample Problem: Draw a model of two gaseous compounds in a homogeneous mixture.

What do you need to know to draw your model?What is a homogeneous mixture?What might a gaseous compound look like?How many compounds are in this mixture?

There is more than one drawing possible.

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Practice Describe the picture:

1. What type of mixture is this? 2. How many compounds? 3. What state of matter?

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Drawing ModelsDrawing Models

Which of the following drawings best represents a homogeneous mixtures of two gaseous compounds?

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Drawing ModelsDrawing Models

The best answer is “b.”

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• 2 types of molecules are uniformly mixed• Atoms are colored to represent different elements

• Not homogeneous

• 3 different compounds, not 2

“b” & “c” are space-filling models. “a” is a ball-and-stick model. Both are acceptable.

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Drawing ModelsDrawing Models

Work in pairs on WKST U1B.5- Modeling Matter

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Do Now

What is a solution?

Describe the difference between a heterogeneous and homogeneous mixture

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Objectives

SWBAT review the differences between types of mixtures.

SWBAT create a concept chart of substances and mixtures and provide examples of each.

SWBAT differentiate between symbol, element, compound, and molecule.

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Matter

MATTER:MATTER: IS ANYTHING THAT HAS MASS IS ANYTHING THAT HAS MASS & OCCUPIES SPACE.& OCCUPIES SPACE.

WATERWATER IS MATTER. IS MATTER.

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A. Matter Flowchart

MATTER

Can it be physically separated?

Homogeneous Mixture(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically decomposed?

noyesIs the composition uniform?

noyes

Colloids Suspensions

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Substances Dissolve in WaterSubstances Dissolve in Water

Aqueous solutions – water based solutions SOLUTE- substance that is being

dissolved SOLVENT- substance that dissolves

the solute (usually water, in aqueous solutions it is water)

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SolutionsSolutions

All solutions are homogeneous mixtures

A solute dissolves in a solvent to make a solution

Solutions are clear but not necessarily colorless

A conductivity test indicates the presence of dissolved charged particles

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Substances Dissolve in WaterSubstances Dissolve in Water

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Sample Solute Solvent

Salt Water

Coffee

lemonade

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Matter is divided into a mixture or a substance

Substance: Definite composition, not physically able to

separate

Mixture: two or more substances coming together but

keeping their individual properties “Foul Water” was a mixture of water, used

coffee grinds, oil, garlic powder, salt

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Types of Mixtures

Homogeneous Mixture: Composition is the same or uniform

throughout

Heterogeneous Mixture: Composition is not the same or uniform

throughout.

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2 Types of Heterogeneous Mixtures2 Types of Heterogeneous Mixtures

Suspension – heterogeneous mixture containing large, solid particles that can settle out or be separated by filtration

Colloid – heterogeneous mixture containing particles too small to settle out – cloudy – Tyndall effect

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Types of Substances

Elements: One type of atom

Compounds: Two or more types of atoms chemically

bonded together

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A. Matter Flowchart Examples:

graphite

pepper

sugar (sucrose)

paint

soda

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A. Matter Flowchart Examples:

graphite

pepper

sugar (sucrose)

paint

soda

element

hetero. mixture

compound

hetero. mixture

solution

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Mixtures(variable composition)

Homogeneous – Solutions evenly distributed

Heterogeneous not evenly distributed

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Diatomic Elements

Hydrogen Nitrogen Oxygen Fluorine Chlorine Bromine Iodine

There are 7 diatomic elements

These atoms are never alone, if they are the pair up with the same atom

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C. Mixtures Examples:

mayonnaise

muddy water

fog

saltwater

Italian salad dressing

colloid

suspension

colloid

solution

suspension

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Do Now

Fill in table on worksheet Unit1B4,6&9

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Objectives

Distinguish between symbols, chemical formulas and equations

Determine the number of protons, electrons and neutrons in an atom

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Symbols, Formulas, & EquationsSymbols, Formulas, & Equations

The international language of chemistry includes symbols, formulas, & equations.Symbols are like letters.Formulas are like words.Equations are like sentences.

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The “letters”The “letters”Symbols – Elements Symbols – Elements

Elements are organized on the Periodic Table of Elements

Each element is represented by a symbol Capital letter Capital letter &

lower case letter Find some of these

symbols on the Periodic Table.

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The Periodic Table of Elements contains much more useful information than just symbols.

You will be learning more about this table throughout this course.

People use aluminum to make a variety of products, including foil, cans, & lightweight construction materials.

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Silicon has properties that lie between those of metals and nonmetals. It is classified as a metalloid. One of its primary uses is in electronic devices.

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Sulfur is a nonmetal used in products such as fungicides and rubber of automobile tires.

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The “words”The “words”FormulasFormulas

Formulas represent specific chemical substances.

Formulas are made of symbols.

Formulas may include subscripts.

A subscript refers back to the symbol immediately before it. A “1” is “understood” & not written.

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Examples

CO 1 carbon & 1 oxygen

CO2

1 carbon & 2 oxygens NH3

1 nitrogen & 3 hydrogens H2O

2 hydrogens & 1 oxygen H2SO4

2 hydrogens, 1 sulfur, & 4 oxygens

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Diatomic ElementsDiatomic Elements

Most elements exist as individual atoms and are represented with symbols.

Some elements exist as 2 bonded atoms of the same element.

For example, hydrogen is a diatomic gas, so is always written as H2 when it is an uncombined element.

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The “sentences”The “sentences”EquationsEquations

Equations give the details of chemical reactions

Chemical reactions involve the breaking & making of chemical bonds, causing atoms to be rearranged into new substances.

The new substances have different properties from those of the original materials.

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The “sentences”The “sentences”EquationsEquations

The original substances (reactants) are written first. Then, an arrow points to the new substances that are made (products).

reactants productshydrogen + oxygen water

2H2 + O2 2H2O Note that this equation is “balanced.”

The total number for each kind of atom is the same for both reactants & products. 53

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Oxygen

O15.99

8

(number of protons)

(and number of electrons if neutral)

(number of protons and neutrons)

(Oxygen)

Atomic

Number

Atomic MassAtomic Mass

Element

Symbol

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Practice Problems

N7

9.01

4

Ne20

C12.02

Complete the missing information and include the number of protons, neutrons, and electrons.

Worksheet- Unit 1 B.7 part 2- Using the Periodic Table

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Complete

Worksheet Unit1B7 Worksheet Unit1B7 part 2

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HW

Pg 50-51 (5-18)

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Do Now: Pg 51 (19-20) & Complete the table below:

Element/ Name

AtomicNumber

Atomic Mass

# protons

# electrons

# neutrons

Na________

W________

Au________

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Objectives

SWBAT draw out Lewis Diagrams of different atoms

SWBAT identify ions as cations and anions and be able to determine the formula for ions and be able to name them.

SWBAT work in groups to answer questions as a conclusion to activity

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Parts of the Atom Proton-

In nucleus, positive charge and a mass of 1

Neutron- In nucleus, neutral charge and a mass

of 1 Electron-

Outside nucleus, negative charge and no mass

+

-

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Complete the chart

Part of Atom

Charge Mass

Proton

Neutron

Electron

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So… if this is an atom…

What makes atoms different? How is carbon different from

oxygen? Different numbers of protons

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Rubbing a balloon against your hair results in static electricity.

Clothes taken out of the drier often show static cling.

The shock that you sometimes receive after you walk across a rug & touch a doorknob is another example of matter’s electrical nature.

What causes these phenomena?

Static cling is best seen when the humidity is low.

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Attraction & RepulsionAttraction & Repulsion

The electrical properties of matter can be summarized as follows:

What are these positive and negative particles?

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Subatomic ParticlesSubatomic Particles

Every neutral (uncharged) atoms contains an equal number of positively charged protons (+) and negatively charged (-) electrons.# of (+) protons = # of (-) electrons

Positive-Negative attractions between the protons in one atoms the electrons in another atom hold atoms together in bonds.

Most atoms also contain neutral particles having no charge (0) called neutrons. 65

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Lewis Dot Structure

Valence Electrons: outermost electrons

Electron Configuration:Energy Level MAX. # of electrons

1st 2

2nd 8

3rd 8

4th 18

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Determining approximate placement of electrons

Chlorine (atomic #_____) # protons = _____# electrons = _____

Energy Level MAX. # of electrons

1st

2nd

3rd

4th

Outermost energy level: _________

# of valence electrons: __________

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Lewis Dot Structure:

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Practice:

Draw the Lewis Dot Diagrams for the following Atoms:

Ca

Li

F Worksheet: Unit 1 B.9 Valence Electrons

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Ions and Ionic CompoundsIons and Ionic Compounds

Recall: Molecules make up one kind of compound.

Ions make up another kind of compound.

Ions are electrically charged atoms (or groups of atoms).

Ions are formed when neutral atoms gain or lose electrons.

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IonsIons

Ions are electrically charged atoms (or groups of atoms).

Ions are formed when neutral atoms gain or lose electrons.

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IonsIons

Recall: What charge do electrons carry?Negative

When atoms gain negative electrons, they form negative ions.

When atoms lose negative electrons, they form positive ions.

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IonsIons

For example, sodium (Na) is # 11 on the Periodic Table.

It has 11 (+) protons and 11 (-) electrons. If it lost 1 (-) electron, it would have 11 (+)

protons and 10 (-) electrons. It has one more proton than electrons, so it

has a charge of -1. The symbol for a sodium ion is Na1+ or just

Na+. (The 1 is understood.)

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IonsIons

For another example, chlorine (Cl) is # 17 on the Periodic Table.

It has 17 (+) protons and 17 (-) electrons. If it gained 1 (-) electron, it would have 17

(+) protons and 18 (-) electrons. It has one less proton than electrons, so it

has a charge of +1. The symbol for a chloride ion is Cl1- or just

Cl-. (The 1 is understood.)

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Do Now (day 7)

List the number of protons, electrons, and neutrons in each ion O2-

H+

F-

Do any of these atoms have complete valence shells?

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Objectives

SWBAT determine the formulas for ionic compounds

SWBAT name different ionic compounds

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Ionic CompoundsIonic Compounds

Oppositely charged ions connect together to form ionic compounds.

For example, sodium ions (Na+) connect to chloride ions (Cl-) to make sodium chloride (NaCl), or table salt.

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Sodium chloride consists of an equal number of positive and negative ions arranged in a 3-dimensional network called a crystal.

A scanning electron micrograph shows the cubic structure of NaCl crystals.

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A space-filling model of NaCl provides information about how the individual sodium ions & chloride ions are arranged within the salt crystal.

What else does this model suggest about the sodium and chloride ions or sodium chloride?

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If an ionic compound dissolves in water, the individual ions would separate from each other and spread out throughout the water.

To show that they were now in an aqueous solution, an (aq) would be added after the symbols for the ions.

Na+(aq) Cl- (aq)

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More about IonsMore about Ions

Cation – positive ion

Anion – negative ion

Monoatomic ions (or monatomic)

Polyatomic ions

Na+,

Cl-

Na+, Cl-, Mg2+, O2-, Al3+, N3-

NH4+, CO3

2-, SO42-, PO4

3-

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Common IonsCommon Ions

See text p. 40 for a list of common ions.

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Practice:

Find trends on the periodic table Worksheet # Unit 1 B.9 part 2 Lewis

Dot Structures

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Formulas for Ionic CompoundsFormulas for Ionic Compounds

2 Rules for Writing Formulas for Ionic Compounds

1. Cation first, then anion

2. Correct formula will be neutral, with the fewest number of each ion needed to make the total electrical charge zero

No charges are shown in the formula.

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Practice Problems

NaCl One Na1+ and one Cl1- cancel each other out.

+1 + -1 = 0

CaCl2

One Ca2+ needs two of the Cl1- to cancel it out. +2 + -1 + -1 = 0

Note: Negative monoatomic ions change their ending to “ide.”Examples above are sodium chloride and calcium chloride.

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Formulas Containing Formulas Containing Polyatomic IonsPolyatomic Ions

Formulas for compounds containing polyatomic ions follow the same rules

If a subscript is needed, it follows the entire polyatomic ion, which is enclosed in parentheses

For example, the calcium ion has a +2 charge, and the nitrate ion has a -1 charge

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Formulas Containing Formulas Containing Polyatomic IonsPolyatomic Ions

For example, the calcium ion has a +2 charge (Ca2+), and the nitrate ion has a -1 charge (NO3

1+). Two nitrate ions are needed to balance

out the charge on one calcium ion. The formula for calcium nitrate is:

Ca(NO3)2. No charges are shown in the formula.

Polyatomic ions do not change their endings.

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Naming Ionic Compounds

1. Name the cation, then the anion 2. Have the last few letters changed to –ide

(monoatomic ions only)

Ex. KF, potassium fluoride

Ex. Ca(NO3)2, calcium nitrate

Practice Worksheet Unit 1B.9 & B.10 Ion supplement

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Write the formula and name the following ionic compounds

1. Ca2+ Br-

2. PO43- Ag+

3. CO32- NH4

+

4. Al3+ NO3-

What does the word “ionic” mean?

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Practice:

Worksheet (Unit 1B.9 part 3)

Study for quiz

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IB.11 WATER TESTINGIB.11 WATER TESTING

day10

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Do Now

Explain what charge the following items typically carry and WHY! Lithium Chlorine Calcium

Draw the Lewis Dot diagram for Li+. Draw a picture of a heterogeneous

mixture of elements X and B.

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Objectives

1. SWBAT start to review for the test by going over the answers review questions.

2. SWBAT read and think critically about the Riverwood Fish Kill.

3. SWBAT create 2 possible hypothesis about the Riverwood fish kill.

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CONTENT BELOW MAY OR MAY NOT BE NECESSARY

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Pure vs. Clean WaterPure vs. Clean Water

In the U.S., we all have access to abundant, low cost, clean, but not pure water

Even if the cost was not prohibitive, it would be impossible to have 100% pure water.

Atmospheric gases (e.g., O2, N2, CO2) will always dissolve in the water to some extent.

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HOW DO YOU NARROW DOWN HOW DO YOU NARROW DOWN THE DATA TO GET THE THE DATA TO GET THE ANSWER?ANSWER?

The cause of the fish kill may be related to something suspended in or dissolved in the water. What might it be?

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Chemistry at WorkChemistry at Work

To learn about careers that require knowledge about what you are learning about in class right now, read text pp. 48-49, Environmental Cleanup: It’s a Dirty Job… But That’s the Point

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Concerns Dissolved oxygen (DO) levels – will test Microorganisms – none present Dissolved matter – must consider amounts

& effect of temperature on solubility – will test

Suspended particles – will test Other Information

No illness – water conservation tips – more water trucked in – 3 day crisis expected

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Now what?Now what?

Water experts agree that the fish kill was caused by something either dissolved or suspended in the Snake River.

How can you determine the exact cause? Knowing properties of water & properties

of substances that may be found in it will help.

Knowing language of chemistry will help you communicate your findings.

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