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Ionic Compounds and Metals

Section 7.1 Ion Formation

Section 7.2 Ionic Bonds and Ionic

Compounds

Section 7.3 Names and Formulas

for Ionic Compounds

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Section 7-1


• Define a chemical bond. octet rule: atoms tend to gain, lose, or share electrons in order to acquire eight valence electrons

chemical bond

cation

anion

• Describe the formation of

positive and negative ions.

• Relate ion formation to

electron configuration.

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

Section 7-1

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.

Section 7-1

Valence Electrons and Chemical Bonds (cont.)

• 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.

CMC In Motion/CMC_t07_1.swf

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.

Positive Ion Formation (cont.)

• Metals are reactive because they lose valence electrons easily.

Section 7-1

Positive Ion Formation (cont.)

• 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.

Section 7-1

Negative Ion Formation (cont.)

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

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

A. A

B. B

C. C

D. D

Section 7-1

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Section 7.1 Assessment

Oxygen gains two electrons to form what kind of ion?

A. 1– anion

B. 2– anion

C. 1+ cation

D. 2+ cation

A. A

B. B

C. C

D. D

Section 7-1

A B C D

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Elements with a full octet have which configuration?

A. ionic configuration

B. halogen configuration

C. noble gas configuration

D. transition metal configuration

Section 7-2

Section 7.2 Ionic Bonds and Ionic Compounds

• Describe the formation of ionic bonds and the

structure of ionic compounds.

compound: a chemical combination of two or more different elements

• Generalize about the strength of ionic bonds based

on the physical properties of ionic compounds.

• Categorize ionic bond formation as exothermic or

endothermic.

Section 7-2


(cont.)

ionic bond

ionic compound

crystal lattice

electrolyte

lattice energy

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

Section 7-2

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.

Section 7-2

Formation of an Ionic Bond (cont.)

CMC In Motion/CMC_P211.AVI

Section 7-2

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.

Section 7-2

Properties of Ionic Compounds (cont.)

• 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.

Section 7-2

Energy and the Ionic Bond

• Reactions that absorb energy are endothermic.

• Reactions that release energy are exothermic.

Section 7-2

Energy and the Ionic Bond (cont.)

• 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.

Section 7-2


• 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.

Section 7-2


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

A. A

B. B

C. C

D. D

Section 7-2


A B C D

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What is the electrostatic charge holding two ions together?

A. covalent bond

B. pseudo-noble gas bond

C. crystal lattice bond

D. ionic bond

Section 7-3

Section 7.3 Names and Formulas for

Ionic Compounds

• Relate a formula unit of an ionic compound to its

composition.

nonmetal: an element that is generally a gas or a dull, brittle solid and is a poor conductor of heat and electricity

• Write formulas for ionic compounds and oxyanions.

• Apply naming conventions to ionic compounds and

oxyanions.

Section 7-3

Section 7.3 Names and Formulas for

Ionic Compounds (cont.)

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.

Section 7-3

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.

Section 7-3

Formulas for Ionic Compounds (cont.)

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

• Monatomic ions are one-atom ions.

Section 7-3


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

Section 7-3


• 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.

Section 7-3


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

• Never change subscripts of polyatomic ions, place in parentheses and write the appropriate subscript outside the parentheses.

Section 7-3


Section 7-3

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.

Section 7-3

Names for Ions and Ionic Compounds (cont.)

Section 7-3


• 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.

Section 7-3


A. A

B. B

C. C

D. D

Section 7-3


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What is the name of the compound CaOH?

A. calcium oxide

B. calcium(I)oxide

C. calcium hydroxide

D. calcium peroxide

Study Guide 1


Key Concepts

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

• 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.

Study Guide 2


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.

Study Guide 2

Section 7.2 Ionic Bonds and Ionic Compounds (cont.)

Key Concepts

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

Study Guide 3

Section 7.3 Names and Formulas for Ionic Compounds

Key Concepts

• A formula unit gives the ratio of cations to anions in the ionic compound.

• 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.

Study Guide 3

Section 7.3 Names and Formulas for Ionic Compounds (cont.)

Key Concepts

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

A. A

B. B

C. C

D. D

Chapter Assessment 1

A B C D

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Cations form when atoms _______ electrons.

A. gain

B. lose

C. charge

D. delocalize

A. A

B. B

C. C

D. D

Chapter Assessment 3

A B C D

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Give the name of the following: NaClO4

A. sodium hypochlorite

B. sodium chlorite

C. sodium chlorate

D. sodium perchlorate

A. A

B. B

C. C

D. D

STP 3

A B C D

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What is the oxidation state of copper in Cu(II)Cl2?

A. 1+

B. 2+

C. 2–

D. unable to determine

A. A

B. B

C. C

D. D

STP 4

A B C D

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Which elements naturally occur with a full octet of valence electrons?

A. alkali metals

B. alkali earth metals

C. halogens

D. noble gases

A. A

B. B

C. C

D. D

STP 5

A B C D

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How many electrons are in a full octet?

A. 10

B. 8

C. 6

D. 4

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