Chapter 7: Ionic and Metallic Bonding. Section 7.1: Ions

Chapter 7:Chapter 7:

Ionic and Metallic BondingIonic and Metallic Bonding

Section 7.1: IonsSection 7.1: Ions

Valence ElectronsValence ElectronsElectrons that are in the highest Electrons that are in the highest

occupied energy level of an occupied energy level of an atom.atom.

Mostly determine the chemical Mostly determine the chemical properties of an elementproperties of an element

Valence electrons are usually Valence electrons are usually the only electrons involved in a the only electrons involved in a chemical bond.chemical bond.

How many valence electrons?How many valence electrons? Look at the family (or column) it is in on the Look at the family (or column) it is in on the

Periodic Table.Periodic Table. Family 1 has 1 electronFamily 1 has 1 electron Family 2 has 2 electrons…etc.Family 2 has 2 electrons…etc.

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Ga Ge As Se Br Kr

Rb Sr In Sn Sb Te I Xe

Cs Ba Tl Pb Bi Po At Rn

1

2 3 4 5 6 7

8or 2

Electron Dot Structure Electron Dot Structure (a.k.a. Lewis Dot Diagram)(a.k.a. Lewis Dot Diagram)

How do you draw Electron Dot Structures?How do you draw Electron Dot Structures?

Write the element symbol. Write the element symbol. Determine what family it is in.Determine what family it is in.

NaNa Then…put dots around the symbol to represent Then…put dots around the symbol to represent

the valence electrons.the valence electrons.

Practice these:Practice these:

BB

NeNe

The Octet RuleThe Octet Rule

Atoms tend to gain or lose electrons Atoms tend to gain or lose electrons to achieve the electron configuration to achieve the electron configuration of a noble gas (8 eof a noble gas (8 e--) )

Noble gas configuration is 8 electrons Noble gas configuration is 8 electrons in its highest orbital:in its highest orbital:

nsns22npnp66

Exception is H and He: only 2 Exception is H and He: only 2 electrons to fill highest orbitalelectrons to fill highest orbital

CationsCationsDefinition: A Definition: A positivelypositively charged ion. charged ion.

CaCattionionHas a + sign in word.Has a + sign in word.Cation is an atom that has Cation is an atom that has LOSTLOST

electrons.electrons.Naming: Naming:

element name (NO change)element name (NO change)Add word “ion”Add word “ion”

Examples of CationsExamples of Cations

LiLi+1+1

Lithium ionLithium ionNaNa+1+1

Sodium ionSodium ionMgMg+2+2

Magnesium ionMagnesium ion

AnionsAnions

Definition: A Definition: A negativelynegatively charged ion. charged ion.

AnionAnionLetter “A” has negative signLetter “A” has negative signAnion is an atom that has Anion is an atom that has GAINEDGAINED

electrons.electrons.Naming: Naming:

Change end of element to ”-ide”Change end of element to ”-ide”Add word “ion”Add word “ion”

Examples of AnionsExamples of Anions

BrBr-1-1

Bromide ionBromide ionOO-2-2

Oxide ionOxide ionClCl-1-1

Chloride ionChloride ion

Section 7.2: Section 7.2: Ionic Bonds and Ionic Ionic Bonds and Ionic

CompoundsCompounds

Review…Review…MagnesiumMagnesium# of valence electrons# of valence electrons

22Gain or lose to achieve octet?Gain or lose to achieve octet?

lose 2lose 2Most stable ion formed:Most stable ion formed:

MgMg+2+2

Cation or Anion?Cation or Anion?Positive, so it’s a cationPositive, so it’s a cation

Ionic Compounds:Ionic Compounds:Compounds made up of metal cation Compounds made up of metal cation

and nonmetal anions.and nonmetal anions.

Ionic BondsIonic BondsThe electrostatic force that holds The electrostatic force that holds

ions together.ions together.Positive cations and negative Positive cations and negative anions attract each other.anions attract each other.

Chemical formula:Chemical formula:Shows the number and kinds of elements in a Shows the number and kinds of elements in a

compound.compound.Always written with symbols and subscripts.Always written with symbols and subscripts.

For example:For example:

LiLi22OO

NaClNaCl

HH22SOSO44

Electron Dot Structure and Ionic Electron Dot Structure and Ionic BondsBonds

Sodium and IodineSodium and Iodine

Naming Ionic CompoundsNaming Ionic Compounds

3 rules:3 rules:

1)1) Name of cation stays the same.Name of cation stays the same.

2)2) Change the end of the anion to “-Change the end of the anion to “-ide”ide”

3)3) If there is a polyatomic ion, the If there is a polyatomic ion, the name doesn’t change. (see chart name doesn’t change. (see chart on page 192)on page 192)


Magnesium and SulfurMagnesium and Sulfur


Potassium and PhosphorusPotassium and Phosphorus


Aluminum and OxygenAluminum and Oxygen

Properties of Ionic CompoundsProperties of Ionic Compounds

Crystalline solids at room temperature.Crystalline solids at room temperature.

Generally have a high melting point (the Generally have a high melting point (the elements are highly attracted to each other elements are highly attracted to each other so they are hard to separate).so they are hard to separate).

They conduct an electric current when They conduct an electric current when melted or dissolved.melted or dissolved.

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Chapter 7: Ionic and Metallic Bonding. Section 7.1: Ions