1

Ionic and Metallic Ionic and Metallic BONDINGBONDING

Ionic and Metallic Ionic and Metallic BONDINGBONDING Chapters 5 (and a Chapters 5 (and a

little of 4)little of 4)

2

Simple Ions

Ion– An atom that has gained or lost one or more

electrons

• Cations– Ions with a positive charge– Have more protons than electrons

• Anions– Ions with a negative charge– Have more electrons than protons

Ex. Ex. MgMg 2+2+

Ex.Ex. Cl Cl --

3

IonsIons

• typically have a Noble Gas Configuration– Groups 1,2 and 3 have configurations with noble gases in the

previous period

– Groups 15-17 have configurations with noble gases in the same period

– Atoms gain or lose electrons to become isoelectronic with a noble gas.

Octet Rule– Atoms tend to gain, lose, or share electrons until they

have eight valence electrons.

4

Group 1 Group 2 Group 3 Group 13 Group 15 Group 16 Group 17

Li Be N O F

Na Mg Al P S Cl

K Ca Sc As Se Br

Rb Sr Y Te I

Cs Ba La

Group 18Noble Gases

Helium

He

Neon

Ne

Argon

Ar

Krypton

Kr

Xenon

Xe

++

++

++

++

++

2+2+

2+2+

2+2+

2+2+

2+2+ 3+3+

3+3+

3+3+

3+3+

33--

33--

33--

22--

22--

22--

22--

--

--

--

--

Some Ions w/ Noble Gas ConfigurationsSome Ions w/ Noble Gas Configurations

5Lewis Symbols

Lewis symbols show the valence electrons as dots arranged around the atomic symbol.

hydrogen:

sodium:

chlorine:

Na

H

Cl

6Valence electrons for Elements• Recall how to determine the valence electron for the elements based on the elements position on the periodic table.Recall how to determine the valence electron for the elements based on the elements position on the periodic table.

• Lewis Dot SymbolLewis Dot Symbol

1 2 13 14 15 16 17 18

7

Chemical Bonding• Compounds are formed from chemically bound atoms

or ions.

• Bonding involves ONLY the valence electrons.

• There are three main types of chemical bonding:

– Metallic bonding (Chapter 4)

– Ionic bonding (Chapter 5)

– Covalent (or molecular) bonding (Chapter 6)

8

Chemical Bonding cont…

• What is an Ionic Bond?– An ionic bond is a chemical bond

resulting from the TRANSFER of electrons from one bonding atom to another

– An ionic bond is the coulombic force of attraction between ions of opposite charge.

• When is an Ionic bond formed?

– An ionic bond is formed when a cation (positive ion) transfers electrons to an anion (negative ion).

9Chemical Bonding cont…

• What is a Metallic Bond?

– A metallic bond occurs in metals (both pure metals and alloys). A metal consists of positive ions surrounded by a “sea” of mobile electrons

– Outermost electrons wander freely through metal.

Metallic Bonding

10Ionic Vs. Metallic

Metallic Compounds Ionic Compounds

Origin of bonding Free floating valence electrons Electron transfer

Forces between particles

The metal is held together by the strong forces of attraction between the positive nuclei and the delocalised electrons.

•Strong attractions between anions and cations

•Strong repulsions between ions of like charge

Elements present Close on the periodic table

(all metals typically)

Widely separated on the periodic table

(a metal and a nonmetal)

metallic elements present

always usually

Electrical conductivity

Good (solid and liquid) Good, when melted (liquid/molten) or dissolved

State at room temperature

Solid (except Hg) Solid

Melting and boiling points

High High

Other properties Malleable, Ductile

Soft to Hard

Brittle

Hard

11Naming Ionic Compounds

• A nonmetal and a metal will typically combine to form an ionic compound

– Where are the metals on the periodic table?

– Where are the nonmetals on the periodic table?

To the LeftTo the Left

To the RightTo the Right

12Naming Ionic Compounds

• Metals are also equal to

• Nonmetals are also equal to

• The ion with the positive charge (cation) is always written before the ion with the negative charge (anion)

CationsCations

AnionsAnions

Ex. Sodium Chloride Ex. Sodium Chloride

NaClNaCl

Anion Anion (Nonmetal)(Nonmetal)

Cation (Metal)Cation (Metal)

13Naming Ionic Compounds

• How do we name the Cations and Anions?

• Cations – Cations from the main-group metals are typically named

using the element name followed by the word ion

Metal symbol Metal symbol Element nameElement name Ion symbol Ion symbol Cation nameCation name

Na Na sodium sodium NaNa1+1+ sodium ion sodium ion

Al Al aluminum aluminum Al Al 3+3+ aluminum ion aluminum ion

Ca Ca calcium calcium CaCa2+2+ calcium ion calcium ion

14Naming Ionic Compounds

• Anions– Anions from the main-group non-metals are named using

the stem/root of the element name followed by the ending -ide

 

Metal element Metal element symbolsymbol

Element Element namename

Ion Ion symbolsymbol

Anion Anion namename

ClCl chlorchlorineine ClCl1-1- chloride chloride

ionion

BrBr brombromineine Br Br 1-1- bromide bromide

ionion

OO oxoxygenygen OO2-2- oxide ionoxide ion

15Naming Ionic Compounds

• Ionic substances exist with separate anions and cations arrayed in a regular pattern (crystal lattice) so the negative and positive charges cancel.

• The formula (unit cell) can be predicted using the charges on the respective ions as subscripts.

16Naming Ionic Compounds

Here is the formula unit – this formula states that the 2+ charge of the calcium ion can be cancelled out by 1- charges of the two chloride ions.

17Naming Ionic Compounds

Here is the formula unit – this formula states that the 3+ charges of the two aluminum ions can be cancelled out by 2- charges of the three oxide ions.

18Naming Ionic Compounds

• Transition elements form stable ions too

– Up to this point, only metals and non-metals have formed ions

– Not all ions however have a noble-gas configuration

19Naming Ionic Compounds

• Transition elements– If an element can form more than one (1) positive

ion, the charge is indicated by Roman numeral in parentheses followed by the word "ion"

Metal symbolMetal symbol Element nameElement name Ion symbolIon symbol Cation name Cation name (new system)(new system)

FeFe ironiron FeFe2+2+ iron (II) ioniron (II) ion

FeFe ironiron Fe Fe 3+3+ iron (III) ioniron (III) ion

SnSn tintin SnSn2+2+ tin (II) iontin (II) ion

SnSn tintin SnSn4+4+ tin (IV) iontin (IV) ion

CuCu coppercopper CuCu1+1+ copper (I) ioncopper (I) ion

CuCu coppercopper CuCu2+2+ copper (II) copper (II) ionion

20Naming Ionic Compounds

• Many atoms can form oneone ion–So far we have learned about

monatomic ions with the prefix mono- meaning

–Just as the prefix mono means one, the prefix poly- means

–The term POLYATOMIC

– means an ion made up of more than one atom

““oneone””

““many”many”

21Naming Ionic Compounds

• Polyatomic Ions– Atoms are covalently bonded, but as a

whole forms ionic bonds with other ions in the same way simple ions do

– Subscripts never change in a polyatomic ion

– If more than one polyatomic ion is needed, parentheses are put around the polyatomic ion and subscripts are added outside the parentheses

22Naming Ionic Compounds

• Writing Polyatomic Ions

– The trick that works for single atom ions also works for polyatomic ions

23Naming Ionic Compounds

What is the predicted formula for the combination of …

Magnesium Ion Magnesium Ion MgMg2+2+

Carbonate Ion Carbonate Ion COCO

332-2-

What about the combination of …Ammonium Ion Ammonium Ion

NHNH44

1+1+

Phosphate Ion Phosphate Ion POPO

443-3-

24

Quick Review:In an IONIC bond,electrons are lost or gained, resulting in the formation of IONS in ionic compounds.

FK FK+ _

The compound potassium fluoride consists of potassium (K+) ions and fluoride (F-) ions.The ionic bond is the coulombic force of attraction between the positive K+ ion and the negative F- ion.