Chapter 8 Ionic Compounds

I. Forming Chemical Bonds – How do Compounds Form?

•Stability

•Like the noble gases, every element wants to be inert

•Not a nerd

I. Why do atoms form bonds?

Chemical Bond - strong attractive force between atoms or ions in a compound.

• stability - goal is to reach the most energetically favorable condition

• bond energy - energy involved in process of bond forming or bond breaking

• Valence Electrons outermost electrons

3s23p6

Valence Electrons?

Highest Energy Level

How do you represent Valence Electrons?

Electron Dot Structures

1. What is the atomic number of this element?

2. Write the electron configuration.

3. Identify just the valence electrons (hint use the

“A” roman numerals on the periodic table).

How do you represent Valence Electrons? Electron Dot

Structures

4. Write the symbol for the element.

5. Use a dot for each valence electron. s

orbitals on one side p orbitals on remaining

three sides of element.

Try these examples:

Li B N F Be C O Ne

1. shows valence electrons, for example lets try these……

Li B N F Be

C O Ne

Valence

electron

Stable Octet (new words, octet rule): 8 electrons in valence shell, stable configuration

II. Ionic Bonding: process by which one or more electrons are transferred from the valence shell of one atom to the valence shell of another atom. (usually forms salts)

Unstable

Stable

3s1

3s2

3p5

full

octets

11P+

10e-

1+charge

17P+

18e-

1- charge

Electons Transferred = ionic bond

Electrostatic

attraction

Ionic Bonding

8.3. Names and Formulas for Ionic Compounds (8.3 pgs. 221-227)

A. Formulas tell: 1. which elements make up the compound (qualitative) 2. ratios of atoms contained (quantitative)

H2O

Hydrogen & Oxygen in element

# of H’s and

O’s in molecule

B. Made from a metal + a nonmetal

1. metals form (+) ions - cations

2. nonmetals form (-) ions - anions

C. Using ion charge to write formulas

1. write the chemical symbol

2. using the periodic table assign a charge

(to be written as a subscript) 1+ 2+ 3+ 3- 2- 1-

Group IA, IIA, IIIA, VA, VI, VIIA

3. add charges together to equal zero, use charge of one ion as subscript for the other ion, or use criss-cross method

4. when subscripts are equal they reduce to 1

5. for polyatomics (more than one atom combined that has an overall charge)

use parenthesis when subscript is 2 or more

examples:

Calcium chloride

Ca2+ + Cl1- + Cl1- = 0 CaCl2

examples:

Calcium chloride Magnesium phosphate

Aluminum oxide Barium sulfate

Magnesium sulfide Ammonium chloride

CaCl2

Al2O3

MgS

examples:

Magnesium phosphate

Mg2+ PO4

3-

Mg3(PO4)2

2 3

examples:

Barium sulfate

Ammonium chloride

BaSO4

NH4Cl

D. Naming ionic compounds

1. binary compounds - two different kinds of atoms

a. name the first element

b. name the second element,drop the last syllable, add -ide.

examples:

Na2S =

MgO =

Sodium Sulfide

Magnesium Oxide

Naming ternary compounds

2. ternary compounds - name the first element, then name the polyatomic ion

examples:

Ca(NO3)2 =

Na2SO4 =

Calcium Nitrate

Sodium Sulfate

E. atoms that form more than one type of

ion (examples: Cu, Fe, Hg, Pb, Sn)

1. old system - call the ion with the greater charge -ic, and the ion with the lesser change -ous. (use Latin names as roots)

Cu+1 cuprous CuF cuprous fluoride

Cu+2 cupric CuF2 cupric fluoride

Fe+2 ferrous FeF2 ferrous fluoride

Fe+3 ferric FeF3 ferric fluoride

2. new system (or stock system), name ion by atom. The name is followed

by roman numeral telling its charge.

` Cu+1 copper(I)

CuF copper (I) fluoride

Cu+2 copper(II)

CuF2 copper (II) fluoride

Fe+2 Iron(II) FeF2 iron (II) fluoride

Fe+3 Iron(III) FeF3 iron (III) fluoride

Crystal Lattice- three dimensional arrangement of cations & anions

• Crystal shape

• Hard & brittle

• High melting pt

• High boiling pt

• When dissolved,

or molten, conducts

electricity

III. Properties of Ionic Compounds:

List Properties here

Properties of Ionic Solids

Electrons transferred = ionic bond

Electrostatic Attraction

Crystal shape

Unit cell – simplest, repeating unit

IV. Energy and the Ionic Bond:

•During any chemical or physical reaction

energy is neither created or destroyed

•Energy that is absorbed is called endothermic

•Energy that is release is called exothermic

•The formation of ionic compounds from

positive and negative ions is always exothermic.

The compound formed is more stable and of

lower energy.

IV. Energy and the Ionic Bond:

•The energy required to separate one mole of the

ions of an ionic compound is referred to as the

lattice energy.

•The more negative the lattice energy, the stronger

the force of attraction.

•Which would have more negative lattice energy,

lithium chloride or lithium bromide?

Lithium chloride

•MgO is almost four times greater then the lattice

energy of NaF, why?

MgO, charge of the ions is greater

V. Names and Formulas for Ionic

Compounds(8.3 pgs. 221-227)(see previous notes)

Describe a Pot of Gold (physical and

chemical properties of the pot and the

gold coins) High luster

High Melting/Boiling Pt.

Malleable

Ductile

Solid

Conductive

VI. Metallic Bonds and Properties of

Metals (8.4 pgs. 228-231)

1. Metals form a lattice with eight to 12

other metal atoms surrounding each

metal atom.

2. metals have at least one valence electron,

they do not form ions or share their

electrons

3. metals are crowded with electrons and

the outer energy levels of the metal

atoms overlap

VI. Metallic Bonds and Properties of

Metals (8.4 pgs. 228-231)

4. The electron sea

model proposed

that all the metal

atoms in a

metallic solid

contribute their

valence electrons

dot form a “sea”

of electrons.

5. Electrons are not held tightly by any

specific atom, electron are free to move

around and are referred to delocalized

electrons.

6. The attraction of a metallic cation for

delocalized electrons is called a metallic

bond.

Properties of Metallic

Bonding

III. How do you name Salts?

A. Formulas tell: 1. which elements make up the compound (qualitative) 2. ratios of atoms contained (quantitative) H2O

B. Made from a metal + a nonmetal

1. metals form (+) ions - cations

2. nonmetals form (-) ions - anions

C. Using ion charge to write formulas

1. write the chemical symbol

2. using the periodic table assign a charge

(to be written as a subscript)

+1 +2 +3 -3 -2 -1

Group IA, IIA, IIIA, VA, VI, VIIA

3. add charges together to equal zero, use charge of one ion as subscript for the other ion, or use criss-cross method

4. when subscripts are equal they reduce to 1

5. for polyatomics (more than one atom combined that has an overall charge)

use parenthesis when subscript is 2 or more

examples:

Calcium chloride Magnesium phosphate

Aluminum oxide Barium sulfate

Magnesium sulfide Ammonium chloride

CaCl2

Al2O3

MgSO4

Mg3(PO4)2

BaSO4

NH4Cl