Chapter 7 Ionic Compounds and Metals. National Standards for Chapter 7 UCP.1 – Systems, order, and...

Chapter 7

Ionic Compounds and Metals

National Standards for Chapter 7

• UCP.1 – Systems, order, and organization• UCP.2 – Evidence, models, and explanation• A.1 –Abilities necessary to do scientific inquiry• B-1 – Structure of atoms• B-2 – Structure and properties of matter• B-3 – Chemical reactions• B-4 – Motions and forces• B-6 – Interactions of energy and matter• E-1 – Abilities of technological design• E-2 – Understandings about science and technology• G.2 – Nature of scientific knowledge

Vocabulary/Study Guide

• Define each term using the Glossary• Either write on the handout, or use your own

paper• This is due on Test Day, Wednesday, December

18

Section 1: Ion Formation

National Standards:• UCP.1 – Systems, order, and organization• UCP.2 – Evidence, models, and explanation• A.1 –Abilities necessary to do scientific inquiry• B-1 – Structure of atoms• B-2 – Structure and properties of matter

Objectives – Section 1

• Define a chemical bond.

• Describe the formation of positive and negative ions.

• Relate ion formation to electron configuration.REVIEW VOCABULARY:• octet rule: atoms tend to gain, lose, or share electrons in order to

acquire eight valence electrons• ionization energy: refers to how easily an atom loses an electron• electron affinity: indicates how much attraction an atom has for

electrons

New Vocabulary

• chemical bond• cation• anion

• Ions are formed when atoms gain or lose valence electrons to achieve a stable octet electron configuration.

Valence Electrons and Chemical Bonds

• A chemical bond is the force that holds two atoms together.

• Chemical bonds form by the attraction between the positive nucleus of one atom and the negative electrons of another atom.

Valence Electrons and Chemical Bonds

• Atom’s try to form the octet—the stable arrangement of eight valence electrons in the outer energy level—by gaining or losing valence electrons.

Positive Ion Formation

• A positively charged ion is called a cation.

• This figure illustrates how sodium loses one valence electron to become a sodium cation.


• Metals are reactive because they lose valence electrons easily.


• Transition metals commonly form 2+ or 3+ ions, but can form greater than 3+ ions.

• Other relatively stable electron arrangements are referred to as pseudo-noble gas configurations.

Negative Ion Formation

• An anion is a negatively charged ion.

• The figure shown here illustrates chlorine gaining an electron to become a chlorine ion.

Negative Ion Formation

• Nonmetal ions gain the number of electrons required to fill an octet.

• Some nonmetals can gain or lose electrons to complete an octet.

Transparency 22: Formation of Ions

Math Transparency 7: Calculating Number of Electrons and Predicting Ionic Change

Homework, Section 1

• SECTION 1 REVIEW, Page 209• Questions #1-6• Answer with complete sentences• Due tomorrow

Section 2: Ionic Bonds and Ionic Compounds

National Standards:• UCP.1 – Systems, order, and organization• UCP.2 – Evidence, models, and explanation• B-1 – Structure of atoms• B-2 – Structure and properties of matter• B-3 – Chemical reactions• B-4 – Motions and forces• B-6 – Interactions of energy and matter


• Describe the formation of ionic bonds and the structure of ionic compounds.

• Generalize about the strength of ionic bonds based on the physical properties of ionic compounds.

• Categorize ionic bond formation as exothermic or endothermic.

Review Vocabulary:• compound: a chemical combination of two or more different

elements

New Vocabulary

• ionic bond• ionic compound• crystal lattice• electrolyte• lattice energy

• Oppositely charged ions attract each other, forming electrically neutral ionic compounds.

Formation of an Ionic Bond

• The electrostatic force that holds oppositely charged particles together in an ionic compound is called an ionic bond.

• Compounds that contain ionic bonds are called ionic compounds.

• Binary ionic compounds contain only two different elements—a metallic cation and a nonmetallic anion.

Formation of an Ionic Bond

Mini-Lab: What compounds conduct electricity in solution?

Transparency 23: Ionic Bonds

• Practice Problems #7-11, page 212

Properties of Ionic Compounds

• Positive and negative ions exist in a ratio determined by the number of electrons transferred from the metal atom to the non-metal atom.

• The repeating pattern of particle packing in

an ionic compound is called an ionic crystal.


• The strong attractions among the positive and negative ions result in the formation of the crystal lattice.

• A crystal lattice is the three-dimensional geometric arrangement of particles, and is responsible for the structure of many minerals.


• Melting point, boiling point, and hardness depend on the strength of the attraction.


• In a solid, ions are locked into position and electrons cannot flow freely—solid ions are poor conductors of electricity.

• Liquid ions or ions in aqueous solution have electrons that are free to move, so they conduct electricity easily.

• An ion in aqueous solution that conducts electricity is an electrolyte.


• This figure demonstrates how and why crystals break when an external force is applied.

Lab: Synthesize an Ionic Compound, page 230

Lab: Properties of Ionic Compounds

Energy and the Ionic Bond

• Reactions that absorb energy are endothermic.

• Reactions that release energy are exothermic.


• The energy required to separate 1 mol of ions in an ionic compound is referred to as the lattice energy.

• Lattice energy is directly related to the size of the ions that are bonded.


• Smaller ions form compounds with more closely spaced ionic charges, and require more energy to separate.

• Electrostatic force of attraction is inversely related to the distance between the opposite charges.

• The smaller the ion, the greater the attraction.


• The value of lattice energy is also affected by the charge of the ion.

Data Analysis Lab: Interpret Data, page 216

• Can embedding nanoparticles of silver into a polymer give the polymer antimicrobial properties?

Lab: Formation of a Salt

Homework, Section 2


Section 3: Names and Formulas for Ionic Compounds

National Standards:• UCP.1 – Systems, order, and organization• UCP.2 – Evidence, models, and explanation• B-2 – Structure and properties of matter• E-2 – Understandings about science and

technology• G.2 – Nature of scientific knowledge


• Relate a formula unit of an ionic compound to its composition.

• Write formulas for ionic compounds and oxyanions.

• Apply naming conventions to ionic compounds and oxyanions.

Review Vocabulary:• nonmetal: an element that is generally a gas or a dull, brittle

solid and is a poor conductor of heat and electricity

New Vocabulary

• formula unit• monatomic ion• oxidation number• polyatomic ion• oxyanion

• In written names and formulas for ionic compounds, the cation appears first, followed by the anion.

Formulas for Ionic Compounds

• When writing names and formulas for ionic compounds, the cation appears first followed by the anion.

• Chemists around the world need to communicate with one another, so a standardized system of naming compounds was developed.


• A formula unit represents the simplest ratio of the ions involved.

• Monatomic ions are one-atom ions.


• Oxidation number, or oxidation state, is the charge of a monatomic ion.


• The symbol for the cation is always written first, followed by the symbol of the anion.

• Subscripts represent the number of ions of each element in an ionic compound.

• The total charge must equal zero in an ionic compound.


• Polyatomic ions are ions made up of more than one atom.

• Since polyatomic ions exist as a unit, never change subscripts of the atoms within the ion. If more than one polyatomic ion is needed, place parentheses around the ion and write the appropriate subscript outside the parentheses.


Transparency 24: Formulas for Ionic Compounds

Math Transparency 8: Determining Numbers of Ions

Common Polyatomic IonsIon Name Ion Name

NH4 ammonium IO4

periodateNO2

nitrite C2H3O2 acetate

NO3 nitrate H2PO4

dihydrogen phosphateHSO4

hydrogen sulfate CO32 carbonate

OH hydroxide SO32 sulfite

CN cyanide SO42 sulfate

MnO4 permanganate S2O3

2 thiosulfateHCO3

hydrogen carbonate O22 peroxide

ClO hypochlorite CrO42 chromate

ClO2 chlorite Cr2O7

2 dichromateClO3

chlorate HPO42 hydrogen phosphate

ClO4 perchlorate PO4

3 phosphateBrO3

bromate AsO43 arsenate

IO3 iodate

• Practice problems #19-23, page 221• Practice problems #24-27, page 222

Names for Ions and Ionic Compounds

• An oxyanion is a polyatomic ion composed of an element (usually a non-metal), bonded to one or more oxygen atoms.



• Chemical nomenclature is a systematic way of naming compounds.– Name the cation followed by the anion.– For monatomic cations use the element name.– For monatomic anions, use the root element name and

the suffix –ide.– To distinguish between different oxidation states of the

same element, the oxidation state is written in parentheses after the name of the cation.

– When the compound contains a polyatomic ion, name the cation followed by the name of the polyatomic ion.

• Practice Problems #28-33, page223


Homework, Section 3


Section 4: Metallic Bonds and the Properties of Metals

National Standards:• UCP.1 – Systems, order, and organization• UCP.2 – Evidence, models, and explanation• A.1 –Abilities necessary to do scientific inquiry• B-1 – Structure of atoms• B-2 – Structure and properties of matter• B-3 – Chemical reactions• B-4 – Motions and forces• B-6 – Interactions of energy and matter• E-1 – Abilities of technological design


• Describe a metallic bond.

• Relate the electron sea model to the physical properties of metals.

• Define alloys, and categorize them into two basic types.

Review Vocabulary:• physical property: a characteristic of matter that can be

observed or measured without altering the sample’s composition

New Vocabulary

• electron sea model• delocalized electron• metallic bond• alloy

• Metals form crystal lattices and can be modeled as cations surrounded by a “sea” of freely moving valence electrons.

Metallic Bonds

• Metals are not ionic but share several properties with ionic compounds.

• Metals also form lattices in the solid state, where 8 to 12 other atoms closely surround each metal atom.

Metallic Bonds

• Within the crowded lattice, the outer energy levels of metal atoms overlap.

• The electron sea model proposes that all metal atoms in a metallic solid contribute their valence electrons to form a "sea" of electrons.

• The electrons are free to move around and are referred to as delocalized electrons, forming a metallic cation.

Metallic Bonds

• A metallic bond is the attraction of an metallic cation for delocalized electrons.

Metallic Bonds

• Boiling points are much higher than melting points because of the energy required to separate atoms from the groups of cations and electrons.

Metallic Bonds

• Metals are malleable because they can be hammered into sheets.

• Metals are ductile because they can be drawn into wires.

Metallic Bonds

• Mobile electrons surrounding positively charged nuclei make metals good conductors of electricity and heat.

• As the number of delocalized electrons increases, so does hardness and strength.

Transparency 25: Metallic Bonding

Mini-Lab: Observe Properties, page 227

Metal Alloys

• An alloy is a mixture of elements that has metallic properties.– Ex. Stainless steel, brass, cast iron

• The properties of alloys differ from the elements they contain.– Ex. Steel is iron mixed with at least one other element. Some

properties of iron are present, like magnetism, but steel is stronger than iron.

Metal Alloys

Metal Alloys

• Substitutional alloys are formed when some atoms in the original metallic solid are replaced by other metals of similar atomic structure.

• Interstitial alloys are formed when small holes in a metallic crystal are filled with smaller atoms.

Homework, Section 4


Key Concepts

• A chemical bond is the force that holds two atoms together. In a vacuum, all electromagnetic waves travel at the speed of light.

• Some atoms form ions to gain stability. This stable configuration involves a complete outer energy level, usually consisting of eight valence electrons.

• Ions are formed by the loss or gain of valence electrons.

• The number of protons remains unchanged during ion formation.

Key Concepts

• Ionic compounds contain ionic bonds formed by the attraction of oppositely charged ions.

• Ions in an ionic compound are arranged in a repeating pattern known as a crystal lattice.

• Ionic compound properties are related to ionic bond strength.

• Ionic compounds are electrolytes; they conduct an electric current in the liquid phase and in aqueous solution.

Key Concepts

• Lattice energy is the energy needed to remove 1 mol of ions from its crystal lattice.

Key Concepts

• The arrangement of electrons in an atom is called the atom’s electron configuration.

• A monatomic ion is formed from one atom. The charge of a monatomic ion is its oxidation number.

• Roman numerals indicate the oxidation number of cations having multiple possible oxidation states.

• Polyatomic ions consist of more than one atom and act as a single unit.

Key Concepts

• To indicate more than one polyatomic ion in a chemical formula, place parentheses around the polyatomic ion and use a subscript.

Key Concepts

• A metallic bond forms when metal cations attract freely moving, delocalized valence electrons.

• In the electron sea model, electrons move through the metallic crystal and are not held by any particular atom.

• The electron sea model explains the physical properties of metallic solids.

• Metal alloys are formed when a metal is mixed with one or more other elements.

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