Unit 7: Changes in Unit 7: Changes in MatterMatter

Ch. 19 – Molecules and Ch. 19 – Molecules and CompoundsCompounds

•19.1 Bonding and 19.1 Bonding and MoleculesMolecules

•19.2 Chemical Formulas19.2 Chemical Formulas

•19.3 Comparing Molecules19.3 Comparing Molecules

Chapter 19 Learning GoalsChapter 19 Learning Goals• Relate the chemical behavior of an element, Relate the chemical behavior of an element,

including bonding, to its placement on the periodic including bonding, to its placement on the periodic table.table.

• Identify how elements form chemical bonds and Identify how elements form chemical bonds and the role of electrons in bonding.the role of electrons in bonding.

• Predict the chemical formulas of compounds made Predict the chemical formulas of compounds made up of two different elements.up of two different elements.

• Write chemical formulas for compounds made up Write chemical formulas for compounds made up of many different types of elements.of many different types of elements.

• Calculate the formula mass of a compound and Calculate the formula mass of a compound and compare different compounds based on their compare different compounds based on their formula masses.formula masses.

• Identify the environmental and economic impact Identify the environmental and economic impact of recycling plastics.of recycling plastics.

Chapter 19 Vocabulary TermsChapter 19 Vocabulary Terms

• ionic bondionic bond

• polyatomic ion polyatomic ion

• ProductProduct

• reactantreactant

• Structural formulaStructural formula

• valence electronvalence electron

• chemical bondchemical bond

• chemical formulachemical formula

• covalent bond covalent bond

• energy level energy level

• formula mass formula mass

• ionion

I. CompoundsI. Compounds

A. CompoundsA. Compounds

1. chemical bonds1. chemical bonds

a. the attractive force a. the attractive force that holds atoms or ions that holds atoms or ions togethertogether

2. A compound always has the 2. A compound always has the same chemical formulasame chemical formula

a. water – Ha. water – H22OO

b. salt – NaClb. salt – NaCl

c. table sugar – Cc. table sugar – C1212HH2222OO1111

3. Molecular formula3. Molecular formula

a. a chemical formula that shows a. a chemical formula that shows the number and kinds of atoms the number and kinds of atoms in a molecule, but not the in a molecule, but not the arrangement of atomsarrangement of atoms

b. Hb. H22OO

c. NaClc. NaCl

d. Cd. C1212HH2222OO1111

4. Chemical Structure/Structural 4. Chemical Structure/Structural FormulaFormula

a. a formula that indicates the a. a formula that indicates the location of atoms, groups, or location of atoms, groups, or ions relative to one another in a ions relative to one another in a moleculemolecule

b. indicates the number and b. indicates the number and location of chemical bondslocation of chemical bonds

B. How does structure affect B. How does structure affect properties?properties?

1. compounds with network 1. compounds with network structures are strong solidsstructures are strong solids

a. quartz and sand – SiOa. quartz and sand – SiO22

b. high melting and boiling b. high melting and boiling pointspoints

c. requires a lot of energy to c. requires a lot of energy to break the bondsbreak the bonds

2. Some networks are made of 2. Some networks are made of bonded positive and negative bonded positive and negative ionsions

a. salt – NaCla. salt – NaCl

b. Nab. Na++ and Cl and Cl-- ions are bonded ions are bonded together forming large networkstogether forming large networks

c. increases strength, high c. increases strength, high melting and boiling pointsmelting and boiling points

3. Some compounds are made of 3. Some compounds are made of moleculesmolecules

a. table sugar – Ca. table sugar – C1212HH2222OO1111

b. strong attraction between the b. strong attraction between the atoms, but weak attraction atoms, but weak attraction between the moleculesbetween the molecules

19.1 Bonding and Molecules19.1 Bonding and Molecules

Key QuestionKey Question: :

Why do atoms form Why do atoms form chemical bonds?chemical bonds?

II. Ionic and Covalent BondingII. Ionic and Covalent Bonding

A. What holds bonded atoms A. What holds bonded atoms together?together?

1. the outermost energy level 1. the outermost energy level of a bonded atom is full of of a bonded atom is full of electronselectrons

a. valence electrons – a. valence electrons – atoms want 8atoms want 8

2. bonds can bend 2. bonds can bend and stretch and stretch without breakingwithout breaking

19.1 The Octet Rule19.1 The Octet Rule

19.1 Valence Electrons19.1 Valence Electrons

B. Ionic BondsB. Ionic Bonds

1. ionic bond1. ionic bond

a. a bond formed by the a. a bond formed by the attraction between oppositely attraction between oppositely charged ionscharged ions

2. ion2. ion

a. an atom or group of a. an atom or group of atoms that has lost or gained atoms that has lost or gained one or more electronsone or more electrons

• Ionic bonds are formed when Ionic bonds are formed when atoms gain or atoms gain or lose electronslose electrons

• Sodium and chlorine form an Sodium and chlorine form an ionic bondionic bond to to make sodium chloride (table salt)make sodium chloride (table salt)

b. Lithiumb. Lithium

atomic #atomic #

atomic massatomic mass

neutralneutral ionion

# protons# protons

# neutrons# neutrons

# electrons # electrons

CHARGECHARGE

c. Fluorinec. Fluorine

atomic #atomic #

atomic massatomic mass

neutralneutral ionion

# protons# protons

# neutrons# neutrons

# electrons # electrons

CHARGECHARGE

d. Aniond. Anion

1) negatively charged ion1) negatively charged ion

e. Catione. Cation

1) positively charged ion1) positively charged ion

3. Formed by the transfer of 3. Formed by the transfer of electronselectrons

a. ie – NaCla. ie – NaCl

4. Ionic compounds are in the form 4. Ionic compounds are in the form of networks, not moleculesof networks, not molecules

5. When melted or dissolved in 5. When melted or dissolved in water, ionic compounds conduct water, ionic compounds conduct electricityelectricity

6. Usually formed between metals 6. Usually formed between metals and nonmetalsand nonmetals

C. Covalent BondsC. Covalent Bonds

1. a bond formed when atoms 1. a bond formed when atoms share one or more pairs of share one or more pairs of electronselectrons

2. often formed between 2. often formed between nonmetalsnonmetals

3. ie – water (H3. ie – water (H22O) and sugar O) and sugar (C(C1212HH2222OO1111))

4. usually have a low melting 4. usually have a low melting pointpoint

5. do not conduct electricity 5. do not conduct electricity because they are not chargedbecause they are not charged

6. atoms are not always shared 6. atoms are not always shared equallyequally

D. Polyatomic IonsD. Polyatomic Ions

1. an ion made of two or more 1. an ion made of two or more atomsatoms

a. hydroxide ion - OHa. hydroxide ion - OH--

b. carbonate ion – COb. carbonate ion – CO332-2-

c. ammonium ion - NHc. ammonium ion - NH44++

2. some compounds have both 2. some compounds have both ionic and covalent bonds – made ionic and covalent bonds – made of polyatomic ionsof polyatomic ions

III. Compound Names and III. Compound Names and FormulasFormulas

A. Naming Ionic CompoundsA. Naming Ionic Compounds

1. Names of cations include the 1. Names of cations include the elements of which they are elements of which they are composedcomposed

2. Names of anions are altered 2. Names of anions are altered names of elementsnames of elements

3. Some elements must show 3. Some elements must show their chargetheir charge

4. Writing Chemical Formulas4. Writing Chemical Formulas

*What is the chemical *What is the chemical formula for aluminum fluoride?formula for aluminum fluoride?

a. list the symbols for each iona. list the symbols for each ion

aluminumaluminum

fluoridefluoride

b. write the symbols for the b. write the symbols for the ions with the cation first ions with the cation first

c. Find the least common multiple c. Find the least common multiple of the ions’ chargesof the ions’ charges

- least common multiple of _____ - least common multiple of _____ and ______ is ______and ______ is ______

- to get _____ positive charged, - to get _____ positive charged, need only ______need only ______

- to get _____ negative charges, - to get _____ negative charges, need _______need _______

d. Write the chemical formula d. Write the chemical formula indicating with subscripts how indicating with subscripts how many of each ion are needed to many of each ion are needed to make a neutral compoundmake a neutral compound

5. Determining the charge of a 5. Determining the charge of a transition metal cationtransition metal cation

Iron (III) ion and Oxide ionIron (III) ion and Oxide ion

Fe chargeFe charge

Oxide chargeOxide charge

6. Problems6. Problems

a. lithium oxidea. lithium oxide

b. beryllium chlorideb. beryllium chloride

c. titanium (III) nitridec. titanium (III) nitride

d. cobalt (III) hydroxided. cobalt (III) hydroxide

e. magnesium bromidee. magnesium bromide

f. rubidium oxidef. rubidium oxide

g. lithium nitrideg. lithium nitride

h. potassium sulfateh. potassium sulfate

B. Naming Covalent CompoundsB. Naming Covalent Compounds

1. numerical prefixes are used to 1. numerical prefixes are used to name covalent compounds of name covalent compounds of two elementstwo elements

2. mono is not used on the first 2. mono is not used on the first element in the formulaelement in the formula

3. Problems3. Problems

a. Na. N22OO44

b. BFb. BF33

c. COc. CO

d. COd. CO22

IV. Organic and Biochemical IV. Organic and Biochemical CompoundsCompounds

A. Organic compoundsA. Organic compounds

1. covalently bonded compound 1. covalently bonded compound that contains carbonthat contains carbon

2. organism – a living thing2. organism – a living thing

3. organisms are made of 3. organisms are made of organic compoundsorganic compounds

B. Examples of Organic B. Examples of Organic CompoundsCompounds

1. carbohydrates1. carbohydrates

2. proteins2. proteins

3. lipids (ie – fats)3. lipids (ie – fats)

4. nucleic acids (ie – DNA)4. nucleic acids (ie – DNA)

19.2 Chemical Formulas19.2 Chemical Formulas

Key QuestionKey Question: :

Why do atoms combine in certain ratios?Why do atoms combine in certain ratios?

*Read text section 19.2 AFTER Investigation 19.2

19.2 Chemical Formulas19.2 Chemical Formulas• All compounds All compounds

have an have an electrical electrical charge of zero; charge of zero; that is, they are that is, they are neutralneutral..

19.2 Oxidation Number19.2 Oxidation Number• An An oxidation oxidation

numbernumber indicates how indicates how many electrons many electrons are lost, gained, are lost, gained, or shared when or shared when bonding occurs.bonding occurs.

Common Polyatomic IonsCommon Polyatomic Ions

19.3 Comparing Molecules19.3 Comparing Molecules

Key QuestionKey Question: :

What is the meaning of a chemical formula?What is the meaning of a chemical formula?

*Read text section 19.3 AFTER Investigation 19.3

19.3 Comparing Molecules19.3 Comparing Molecules

• One atom of hydrogen is 1/12 the One atom of hydrogen is 1/12 the mass of a carbon atom.mass of a carbon atom.

19.3 Comparing Molecules19.3 Comparing Molecules

19.3 Comparing Compounds19.3 Comparing Compounds

• The The Avogadro numberAvogadro number is is the number of atoms in the number of atoms in the atomic mass of an the atomic mass of an element element oror the number of the number of molecules in the formula molecules in the formula mass of a compound mass of a compound when these masses are when these masses are expressed in grams. expressed in grams.

• One set of One set of 6.02 x 10236.02 x 1023 atoms or molecules is atoms or molecules is also referred to as a also referred to as a molemole of that substance.of that substance.

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