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Section IV: Moving ElectronsLesson 17 Technicolor AtomsLesson 18 Life on the EdgeLesson 19 Noble Gas EnvyLesson 20 Getting ConnectedLesson 21 Salty EightsLesson 22 Isn’t It Ionic?Lesson 23 Alchemy of PaintLesson 24 Shell Game

Lesson 17: Technicolor Atoms

Flame Tests

ChemCatalystThese drawings are models that show solid copper, solid copper chloride, and aqueous copper chloride as collections of atoms.

1. Describe each model.2. What is similar about each model? What is different?

Cu(s)Solid copper

CuCl2(s)Solid copper (II) chloride

CuCl2(aq)Aqueous copper (II) chloride

Key QuestionWhat evidence is there that certain atoms are present in a compound?

You will be able to:• conduct a flame test and use the results

to determine the identity of a compound• interpret evidence of the presence of

certain atoms within compounds

Prepare for the LabWork in groups.You will be using chemicals and fire today. Follow safety instructions.

Wear safety goggles.Tie back long hair and remove dangling jewelry.Roll up long sleeves and keep clothing

away from flames.Locate the eye wash, fire blanket, and fire extinguisher before starting the lab.

Discussion NotesThe metal element in each chemical formula appears to be responsible for the flame colors.

Only certain elements produce colorful flames.

Flame test: A test used in the laboratory to look for the presence of certain metal atoms. A sample of a compound is heated in a flame, and the resulting color is noted.

Discussion Notes (cont.)Elements and compounds are collections of atoms.

The only way to change one atom into another is to change the nucleus through a nuclear reaction.

Discussion Notes (cont.)Sodium Atom, Na

Discussion Notes (cont.)The illustration indicates that the flame colors are associated with movements of the electrons within the sodium atom.

Bohr’s model of the atom came directly from evidence similar to that produced in class today.

Wrap UpWhat evidence is there that certain atoms are present in a compound?• Many metal atoms produce a

characteristic colored flame when compounds containing those atoms are heated in a flame.

• Flame tests are evidence that elements and compounds are collections of atoms.

Check-inPredict the flame colors produced when heating these substances. Explain your thinking.• copper (II) carbonate• calcium chloride

Lesson 18: Life on the Edge

Valence and Core Electrons

ChemCatalyst1. What do you

notice about the number of spokes on the circles?

2. The spokes represent electrons. Do the spokes represent the total number of electrons? Explain your thinking.

Key QuestionWhy do elements in the same group in the periodic table have similar properties?

You will be able to:• create a shell model diagram of an atom,

placing the correct number of electrons in the correct shells

• explain the difference between a valence electron and a core electron

• describe the patterns in the periodic table associated with electron arrangements

Prepare for the ActivityWork in pairs.

Prepare for the Activity (cont.)The Shell Model

The surface of each sphere represents an area where an electronor a group of electronsis most likely to be found.

Prepare for the Activity (cont.)Electron shells are the levels around the nucleus where electrons can be found.

Sodium and magnesium have electrons in three electron shells.

Discussion NotesThe atomic number of an element is the same as the total number of electrons.

The period (row) number of the element is the same as the number of electron shells.

For main-group elements, the group number of the element is the same as the number of electrons in the outermost shell.

Discussion Notes (cont.)

Table of Valence and Core Electrons

Discussion Notes (cont.)Valence shell: The outermost electron shell in an atom.Valence electrons: The electrons located in the outermost electron shell of an atom.Core electrons: All other electrons in an atom besides the valence electrons.

Discussion Notes (cont.)The arrangement of electrons in their shells is highly predictable.

The numbers of core electrons also exhibit patterns across each row of the periodic table.

Wrap UpWhy do elements in the same group in the periodic table have similar properties?• Electrons occupy distinct areas around the

nucleus called electron shells. The arrangement of electrons in these shells is highly predictable.

• For main group elements, elements in the same group have the same number of valence electrons.

• The number of valence electrons increases across a period.

• The number of shells and the number of core electrons increase as you go down a group.

Check-inProvide each piece of information for element 34.a. The element’s name and symbol.b. The total number of electrons in an atom of this element.c. The number of core electrons in an atom of this element.d. The number of valence electrons.e. The group number for this element.f. The names of other elements with the same

number of valence electrons.

Lesson 19: Noble Gas Envy

Ions

ChemCatalystChemists have found that metal atoms transfer electrons to nonmetal atoms when they form compounds. Examine the shell model showing how a lithium atom might transfer an electron to a fluorine atom.

1. What effect does this electron transfer have on the charge of each atom?

2. What element does each atom resemble after the electron has been transferred?

Key QuestionHow is chemical stability related to the arrangements of electrons in atoms?

You will be able to:• explain that an ion is formed when an

atom loses or gains electrons and state the difference between a cation and an anion

• determine the charge on an ion based on an atom’s placement in the periodic table

• explain the relationship between ion charge and valence electrons

Prepare for the ActivityWork in groups of eight.

Ion: An atom (or group of atoms) that has a positive or negative charge because it has lost or gained electrons.

Discussion NotesThe table of arranged ion cards shows that the charges on ions are quite predictable.

Discussion Notes (cont.)When electrons are removed from or added to an atom, the rest of the atom stays the same.

The charge on an ion is noted with a superscript.

Discussion Notes (cont.)Cation: An ion with a net positive charge. Usually these are formed from metal atoms.

Anion: An ion with a net negative charge. Usually these are formed from nonmetal atoms.

Discussion Notes (cont.)Electron arrangementsof atoms in ioniccompounds resemblenoble gases.

Discussion Notes (cont.)Atoms tend to lose or gain electrons to attain the electron arrangement of a noble gas.

Wrap UpHow is chemical stability related to the arrangements of electrons in atoms?• When atoms gain or lose electrons, they

form ions. Ions are atoms that carry a net positive or net negative charge.

• When atoms lose electrons, they have a positive charge and are called cations.

• When atoms gain electrons, they have a negative charge and are called anions.

• Ions have electron arrangements resembling those of the noble gas atoms.

Check-in1. Draw a shell model for calcium, Ca,

showing the arrangement of its electrons.

2. What would have to happen for an atom of calcium to have an electron arrangement like that of a noble gas? Explain.

Lesson 20: Getting Connected

Ionic Compounds

ChemCatalystMetal elements combine with the nonmetal element chlorine, Cl, to form compounds. The formulas are given in the tables.

1. Compare the three tables. What do you notice?2. Predict the formula of a compound formed between lithium, Li, and chlorine, Cl. Which table would you put it in?

Element

Compound

Na NaCl

K KCl

Element

Compound

Mg MgCl2

Ca CaCl2

Element

Compound

Ne none

Ar none

Key QuestionHow can valence electrons be used to predict chemical formulas?

You will be able to:• predict the chemical formulas of

compounds that will form between metal and nonmetal atoms

• explain how an ionic compound forms and determine whether it follows the rule of zero charge

Prepare for the ActivityWork in pairs.

Ionic compound: An ionic compound is a compound composed of positive and negative ions, formed when metal and nonmetal atoms combine.

Discussion NotesMg2+ + Cl– + Cl– produces MgCl2 with zero charge.

Discussion Notes (cont.)Metal and nonmetal elements combine to form ionic compounds.

The electron arrangements of the cations and anions resemble the arrangements of a noble gas atom.

Discussion Notes (cont.)The rule of zero change can be used to determine the chemical formulas of ionic compounds.

Rule of zero charge: In an ionic compound, the positive charges on the metal cations and the negative charges on the nonmetal anions sum to 0.

Discussion Notes (cont.)Chemical Formulas of Ionic Compounds

Example

Number of

valence electrons

for the metal

Number of

valence electrons

for the nonmetal

Total number

of valence

electrons

Total positive charge

Total negative charge

Total charge

NaF 1 7 8 +1 –1 0

MgO 2 6 8 +2 –2 0

AlN 3 5 8 +3 –3 0K2Se 1 6 8 2(+1) –2 0

MgCl2 2 7 16 +2 2(–1) 0AlF2 3 7 24 +3 3(–1) 0

AL2O2 3 6 24 2(+3) 3(–2) 0

Discussion Notes (cont.)The number of electrons associated with the atoms of an ionic compound generally totals 8 or a multiple of 8.

Wrap UpHow can valence electrons be used to predict chemical formulas?• Metal atoms and nonmetal atoms combine to

form ionic compounds.• In ionic compounds, the metal is considered a

cation, and the nonmetal is considered an anion.• The charges on the cations and the anions in

ionic compounds sum to 0.• Metal atoms and nonmetal atoms usually

combine in ratios that result in a total of eight valence electrons or a multiple of eight valence electrons.

Check-inWhat elements will combine with strontium, Sr, in a 1:1 ratio? Explain your thinking.

Lesson 21: Salty Eights

Formulas for Ionic Compounds

ChemCatalystFind these cards

in Your Salty Eights card deck.

1. List the ionic compounds you can make with pairs of cards, using two different elements.2. List the ionic compounds you can make with three cards and only two different elements.3. What rule must all these compounds satisfy?

Key QuestionHow can you predict chemical formulas and name ionic compounds?

You will be able to:• use valence electrons to predict ionic

compounds• develop proficiency at naming binary

ionic compounds and writing their chemical formulas

Prepare for the ActivityWork in groups of four.

Discussion NotesIn general, atoms come together to form an ionic compound if the number of valence electrons totals 8 or a multiple of 8.

Discussion Notes (cont.)Writing correct chemical formulas is a matter of keeping track of exactly how many atoms come together to make a compound.

Creating correct chemical names is a matter of remembering some basic guidelines.

Wrap UpHow can you predict chemical formulas and name ionic compounds?• Ionic compounds tend to form from atoms

that together have a total of 8 (or a multiple of 8) electrons in their outermost (valence) shells.

• Noble gases already have eight valence electrons and don’t combine with other elements to make new compounds. They are already highly stable.

Check-inWhich of these compounds are likely to form?

a. Na2S b. K2Mg c. AlBr2

d. Na3N e. OCl f. CaO

Lesson 22: Isn’t It Ionic?

Polyatomic Ions

ChemCatalystThe cards show a sodium ion and three polyatomic ions.

1. What do you think a polyatomic ion is?2. Name three compounds formed between sodium ions

and each of the three polyatomic ions. Use the rule of zero charge to write the compounds’ formulas.

Key QuestionWhat is a polyatomic ion?

You will be able to:• recognize and name polyatomic ions• write names and chemical formulas of

compounds with polyatomic ions

Prepare for the ActivityWork in pairs.

Ionic compound: An ionic compound is a compound composed of positive and negative ions, formed when metal and nonmetal atoms combine.

Discussion NotesPolyatomic Ions

Discussion Notes (cont.)Polyatomic ions contain more than one atom.

Most polyatomic ions are anions, with negative charges.

Polyatomic ion: An ion composed of a group of atoms with an overall positive or negative charge. Most polyatomic ions are anions.

Discussion Notes (cont.)The rule of zero charge can be used to predict the formulas of compounds that contain polyatomic ions.

Discussion Notes (cont.)Compounds containing polyatomic ions have their own unique naming guidelines.

Polyatomic ion Name

OH– hydroxide

NO3– nitrate

CO32– carbonate

SO42– sulfate

NH4+ ammonium

Wrap UpWhat is a polyatomic ion?• Polyatomic ions are ions composed of a

group of atoms. The charge is shared by all the atoms.

• To write the formula of an ionic compound that contains polyatomic ions, use the rule of zero charge.

• When naming compounds containing polyatomic ions, simply insert the name of the ion.

Check-in1. What is the name of the compound

Be(NO3)2?2. What ions are present in this

compound, and what are the charges on the ions?

Lesson 23: Alchemy of Paint

Transition Metal Chemistry

ChemCatalyst1. What types of substances will you be

creating in today’s lab?2. What safety precautions are especially

important for today’s lab?3. Describe one of the procedures you will

be completing in class today.

Key QuestionWhat types of compounds are made from transition metals?

You will be able to:• recognize transition metal compounds

and their names• determine the charge on transition metal

ions given their chemical formula

Prepare for the LabWork in groups of four.You will be working with transition metal compounds and acid. Follow lab safety guidelines.• Wear safety goggles at all times.• When heating compounds in a test tube, keep

the open end pointed away from yourself and others.

• If any compound comes in contact with your skin, wash immediately with plenty of water.

• Tie back long hair and loose clothing. Remove any dangling jewelry.

Prepare for the Lab (cont.)To decant and filter a solid, fold filter paper following instructions.

Discussion NotesMany of the paint pigments that artists historically used and continue to use are ionic metal-nonmetal compounds.

Wrap UpWhat types of compounds are made from transition metals?• Many of the colorful pigments used in

painting are formed from metal-nonmetal compounds with transition metal cations.

• Paint pigments in famous paintings can be as valuable as gold. A compound or element does not have to be gold to be valuable.

Lesson 24: Shell Game

Electron Configurations

ChemCatalystThese drawings show two different ways to represent the arrangement of the electrons in atoms of the element calcium, Ca.

1. Name at least two differences in the drawings.2. Name at least two similarities in the drawings.

Key QuestionWhat does the periodic table indicate about the arrangements of electrons?

You will be able to:• describe the structure of an atom in

terms of electron shells and subshells• use the periodic table to determine the

electron arrangement in an atom and to write electron configurations

• explain the organization of the periodic table in terms of the arrangements of electrons in subshells

Prepare for the ActivityWork in pairs.

Discussion NotesThe electron shells in the shell model of an atom (except for n = 1) are divided into subshells.

Shell Number of electrons in the shell Subshell Number of electrons in the subshell

n = 1 2 1s 2

n = 2 82s

2p

2

6

n = 3 183s3p3d

26

10

n = 4 32

4s4p4d4f

26

1014

Discussion Notes (cont.)In an electron configuration, the number indicates the shell number, the letter indicates the subshell within the shell, and the superscript indicates the number of electrons in the subshell.

Electron configuration: A shorthand way to keep track of all the electrons in an atom of an element for all the subshells that have electrons. The number of electrons in each subshell is shown as a superscript.

Discussion Notes (cont.)The periodic table is organized in subshell blocks.

Discussion Notes (cont.)The order of filling subshells does not always correspond to the numerical order of the subshells.

The elements in the different subshell blocks have related properties.

Wrap UpWhat does the periodic table indicate about the arrangements of electrons?• Each electron shell in the shell model, except

for n = 1, is divided into subshells.

• Each subshell can hold a specific maximum number of electrons.

• The periodic table can assist you in figuring out the placement of electrons in subshells.

• Chemists keep track of electrons and the subshells they are in by writing electron configurations.

Check-inIdentify the element with this electron configuration:

1s22s22p63s23p64s23d104p3