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1B. Looking at Water & Its Contaminants. Learning more about the chemistry of water and how substances interact with water. 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.

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1b looking at water its contaminants

1B. Looking at Water & Its Contaminants

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


Do now

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)


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

3


Water has physical properties

Water 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.

4


Physical properties of water

Physical Properties of water:

  • Color – colorless, clear

  • Odor - odorless

  • Density = mass/ volume

    • Temperature dependent

  • Freezing point = 0°C

  • Boiling point = 100°C

  • Surface tension


Pure water

“Pure” Water

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

  • Properties of pure water

    • Clear

    • Colorless

    • Odorless

    • Tasteless

6


Lab demo

Lab Demo

  • Make and record proper observations for each demonstration.


Do now1

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


Do now2

Do Now

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


Objectives1

Objectives

  • SWBAT compare and contrast surface tension between water and alcohol

  • SWBAT define matter and discuss the physical properties of water.

  • SWBAT calculate density


Surface tension

Surface Tension


Surface tension1

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.


Molecular view of surface tension

Molecular view of surface tension


1b looking at water its contaminants

HW

  • Pg 50 (1-4)


Do now3

Do Now

  • Draw:

    • A) a water molecule (H2O)

    • B) 2H2O


Objectives2

Objectives

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

  • SWBAT draw different mixtures and answer questions related to those pictures


Particulate level

Particulate 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

17


Substances

Substances

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)

18


Models representations of atoms molecules

MODELS:REPRESENTATIONS OF ATOMS & MOLECULES

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

19


Drawing models

Drawing 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.

20


Practice

Practice

  • Describe the picture:

  • 1. What type of mixture is this?

  • 2. How many compounds?

  • 3. What state of matter?


Drawing models1

Drawing Models

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

22


Drawing models2

Drawing Models

  • Not homogeneous

  • 2 types of molecules are uniformly mixed

  • Atoms are colored to represent different elements

  • 3 different compounds, not 2

The best answer is “b.”

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

23


Drawing models3

Drawing Models

Work in pairs on WKST U1B.5- Modeling Matter

24


Do now4

Do Now

  • What is a solution?

  • Describe the difference between a heterogeneous and homogeneous mixture


Objectives3

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.


Matter

Matter

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

  • WATER IS MATTER.


A matter flowchart

MIXTURE

PURE SUBSTANCE

yes

no

yes

no

Is the composition uniform?

Can it be chemically decomposed?

Colloids

Suspensions

A. Matter Flowchart

MATTER

yes

no

Can it be physically separated?

Homogeneous Mixture

(solution)

Heterogeneous Mixture

Compound

Element


Substances dissolve in water

Substances 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)

29


Solutions

Solutions

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

30


Substances dissolve in water1

Substances Dissolve in Water

31


Matter is divided into a mixture or a substance

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


Types of mixtures

Types of Mixtures

  • Homogeneous Mixture:

    • Composition is the same or uniform throughout

  • Heterogeneous Mixture:

    • Composition is not the same or uniform throughout.


2 types of heterogeneous mixtures

2 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

35


Types of substances

Types of Substances

  • Elements:

    • One type of atom

  • Compounds:

    • Two or more types of atoms chemically bonded together


A matter flowchart1

A. Matter Flowchart

  • Examples:

    • graphite

    • pepper

    • sugar (sucrose)

    • paint

    • soda


A matter flowchart2

A. Matter Flowchart

element

hetero. mixture

compound

hetero. mixture

solution

  • Examples:

    • graphite

    • pepper

    • sugar (sucrose)

    • paint

    • soda


Mixtures variable composition

Homogeneous – Solutions

evenly distributed

Heterogeneous

not evenly distributed

Mixtures(variable composition)


Diatomic elements

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


C mixtures

C. Mixtures

colloid

suspension

colloid

solution

suspension

  • Examples:

    • mayonnaise

    • muddy water

    • fog

    • saltwater

    • Italian salad dressing


Do now5

Do Now

  • Fill in table on

    worksheet Unit1B4,6&9


Objectives4

Objectives

  • Distinguish between symbols, chemical formulas and equations

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


Symbols formulas equations

Symbols, Formulas, & Equations

  • The international language of chemistry includes symbols, formulas, & equations.

    • Symbols are like letters.

    • Formulas are like words.

    • Equations are like sentences.

44


The letters symbols elements

The “letters”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.

45


1b looking at water its contaminants

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.

46


1b looking at water its contaminants

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.

47


1b looking at water its contaminants

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

48


The words formulas

The “words”Formulas

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.

49


Examples

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


Diatomic elements1

Diatomic 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.

51


The sentences equations

The “sentences”Equations

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.

52


The sentences equations1

The “sentences”Equations

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

    reactants  products

    hydrogen + 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


Oxygen

8

O

15.99

Oxygen

Element

Symbol

Atomic

Number

(Oxygen)

(number of protons)

(and number of electrons if neutral)

Atomic Mass

(number of protons and neutrons)


Practice problems

4

7

C

N

Ne

9.01

12.02

20

Practice Problems

Complete the missing information and include the number of protons, neutrons, and electrons.Worksheet- Unit 1 B.7 part 2- Using the Periodic Table


Complete

Complete

  • Worksheet Unit1B7

  • Worksheet Unit1B7 part 2


1b looking at water its contaminants

HW

  • Pg 50-51 (5-18)


Do now6

Do Now:

  • Pg 51 (19-20) &

  • Complete the table below:


Objectives5

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


Parts of the atom

+

-

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


Complete the chart

Complete the chart


So if this is an atom

So… if this is an atom…

  • What makes atoms different?

  • How is carbon different from oxygen?

    • Different numbers of protons


1b looking at water its contaminants

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.

63


Attraction repulsion

Attraction & Repulsion

The electrical properties of matter can be summarized as follows:

What are these positive and negative particles?

64


Subatomic particles

Subatomic 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


Lewis dot structure

Lewis Dot Structure

  • Valence Electrons: outermost electrons

  • Electron Configuration:


Determining approximate placement of electrons

Determining approximate placement of electrons

  • Chlorine (atomic #_____)

  • # protons = _____# electrons = _____

Outermost energy level: _________

# of valence electrons: __________


Lewis dot structure1

Lewis Dot Structure:


Practice1

Practice:

Draw the Lewis Dot Diagrams for the following Atoms:

  • Ca

  • Li

  • F

  • Worksheet: Unit 1 B.9 Valence Electrons


Ions and ionic compounds

Ions 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.

70


1b looking at water its contaminants

Ions

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

Ions are formed when neutral atoms gain or lose electrons.

71


1b looking at water its contaminants

Ions

  • 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.

72


1b looking at water its contaminants

Ions

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.)

73


1b looking at water its contaminants

Ions

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.)

74


Do now day 7

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?


Objectives6

Objectives

  • SWBAT determine the formulas for ionic compounds

  • SWBAT name different ionic compounds


Ionic compounds

Ionic 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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1b looking at water its contaminants

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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1b looking at water its contaminants

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?

79


1b looking at water its contaminants

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)

80


More about ions

More about Ions

Cation – positive ion

Anion – negative ion

Monoatomic ions (or monatomic)

Polyatomic ions

Na+,

Cl-

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

NH4+, CO32-, SO42-, PO43-

81


Common ions

Common Ions

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

82


Practice2

Practice:

  • Find trends on the periodic table

  • Worksheet # Unit 1 B.9 part 2 Lewis Dot Structures


Formulas for ionic compounds

Formulas 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.

84


Practice problems1

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.


Formulas containing polyatomic ions

Formulas Containing Polyatomic 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

86


Formulas containing polyatomic ions1

Formulas Containing Polyatomic Ions

  • For example, the calcium ion has a +2 charge (Ca2+), and the nitrate ion has a -1 charge (NO31+).

  • 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.

87


Naming ionic compounds

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


1b looking at water its contaminants

  • 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?


Practice3

Practice:

  • Worksheet (Unit 1B.9 part 3)

  • Study for quiz


Ib 11 water testing

IB.11 WATER TESTING

day10

91


Do now7

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.


Objectives7

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.


Content below may or may not be necessary

Content below may or may not be necessary


Pure vs clean water

Pure 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.

96


How do you narrow down the data to get the answer

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

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

97


Chemistry at work

Chemistry 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

98


1b looking at water its contaminants

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


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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