ionic and metallic bonding - Waterford · •all elements are ‘stable’ with an octet of eight valence electrons “Atoms of metals tend to lose their valence electrons, leaving

ionic and metallic

bonding chapter 7

Chemical Nomenclature

The Skill of Writing and

Naming Chemical

Formulas

the b i g idea

• determine the number of valence electrons for an

element.

• determine which elements gain/lose electrons,

the charges their ions carry, and state how ions

are formed.

• differentiate between ionic bonding and covalent

bonding.

you will be able to:

valence electrons -

review • valence electron - outermost energy level electrons

• electrons involved in chemical bonding

• highest energy electrons in an atom / ion

• number of valence electrons - group number of the

element

• transition metals - 2 valence electrons

• atoms will lose, gain, or share electrons to achieve an

electronic structure identical to that of a noble gas

• all elements are ‘stable’ with an octet of eight valence

electrons

“Atoms of metals tend to lose their valence electrons,

leaving a complete octet in the next-lowest energy level.

Atoms of some nonmetals tend to gain electrons or to

share electrons with another nonmetal to achieve a

complete octet.”

the octet rule

Properties of Metals

• Shiny

• Conduct electricity

• Ductile

• Malleable

• Lose electrons

• All but gold and copper are grey in color

Properties of

Nonmetals

• Not shiny

• Most are colored

• Do not conduct electricity

• Not malleable

• Gain electrons

cation formation • element (metal) loses electrons

• K K+ + e-

K+

• element (nonmetal) gains electrons

• P + 3 e- P3-

P3-

anion formation

Ar 18

Oxidation Numbers • The overall charge of an ion after it loses or gains electrons

• Can be determined by looking at the periodic table

Formation of Ionic Compounds • Composed of a metal cation and a nonmetal anion

• METAL is always written FIRST

• Ionic compounds are electrically NEUTRAL

• Overall charge is ZERO

• The total positive charge equals the total negative

charge

chemical formula

• shows the type and number of elements in

the smallest representative unit of a

substance

Writing Formulas for Binary Ionic Compounds

Two simple steps:

• Write the symbol and charge of each ion

• Write the positive ion of metal first, and the negative ion Ba2+ Cl

Cl

• Balance the charges by writing the number of ions needed as subscripts

BaCl2

• SHORTCUT: Use the Crossover Rule

the crossover rule: binary ionic compounds

Mg Mg 2+ F 1- F

Mg 1 F 2

MgF2

Cs Cs + S 2- S

write the neutral chemical formula for the ionic compound formed

between Cs and S atoms

Cs 2 S 1

Cs2S

write the neutral chemical formula for the ionic compound formed

between Mg and F atoms

the crossover rule

Be Be 2+ O 2- O

Be 2 O 2

Be2O2

Ca Ca 2+ As 3- As

write the neutral chemical formula for the ionic compound formed

between Ca and As atoms

Ca 3 As 2

Ca3As2

reduce! BeO

write the neutral chemical formula for the ionic compound formed

between Be and O atoms

Learning Check

Write the correct formula for the compounds containing the

following ions.

A. Na+, S2-

B. Al3+, Cl-

C. Mg2+, N3-

Naming Binary Ionic

Compounds

Name the metal first, then the

nonmetal as -ide

Use name of a metal with a fixed

charge

Groups 1A, 2A, 3A

and Ag, Zn, and Cd

• Examples:

NaCl sodium chloride

ZnI2 zinc iodide

Al2O3 aluminum oxide

Learning Check

Complete the names of the following binary compounds:

Na3N sodium ________________

KBr potassium ________________

Al2O3 aluminum ________________

MgS _________________________

Transition Metals

• Most transition metals and Group 14 metals form 2 or more positive

ions

• Zn2+, Ag+, and Cd2+ form only one ion

Names of Variable Charge Metals

• Use a Roman Number after the name of a metal that forms two or more ions

• Transition metals and the metals in groups 14 and 15

Lead Pb2+ lead(II)

Pb4+ lead(IV)

Names of Variable Charge Metals

Learning Check

Complete the names of the following binary compounds with

variable metal ions:

FeBr2 iron (_____) bromide

Cu2O copper (_____) oxide

SnCl4 ___ ( _____ ) ______________

Fe2O3 ________________________

CuS ________________________

polyatomic ions: ternary

ionic compounds • cations and anions composed of two or more

atoms

• the entire ion ‘assumes’ the positive or negative

charge

• behave in the same manner as monatomic (single

atom) ions

Three Possible Types of

Ternary Ionic Compounds

• Ammonium cation + anion (nonmetal)

• Cation (metal) + polyatomic anion

• Ammonium cation + polyatomic

anion

the crossover rule - polyatomic ions

Li Li + NO3 -1

write the neutral chemical formula for the ionic compound formed

between lithium and nitrate

Li 1 NO 3

LiNO3

the crossover rule - polyatomic ions

NH4 +

write the neutral chemical formula for the ionic compound formed between

ammonium and oxygen

NH4 2 O 1

(NH4)2O

O 2- O

parenthesis for polyatomic ions when there is more than one in the formula

the crossover rule - polyatomic ions

Ba 2+

write the neutral chemical formula for the ionic compound formed between

barium and phosphate

Ba 3 PO 4 2

Ba3(PO4)2

PO4 3-

parenthesis for polyatomic ions when there is more than one in the formula

Learning Check

1. aluminum nitrate

a) AlNO3 b) Al(NO)3 c) Al(NO3)3

2. copper(II) nitrate

a) CuNO3 b) Cu(NO3)2 c) Cu2(NO3)

3. Iron (III) hydroxide

a) FeOH b) Fe3OH c) Fe(OH)3

4. Tin(IV) hydroxide

a) Sn(OH)4 b) Sn(OH)2 c) Sn4(OH)

Mixed Practice

Binary and Ternary Ionic Compunds

Write the formula:

• Copper (II) chlorate

• Calcium nitride

• Aluminum carbonate

• Potassium bromide

• Barium fluoride

• Cesium hydroxide

Naming Ternary Compounds

• Contains at least 3 elements

• There MUST be at least one polyatomic ion

• It helps to circle the ions

• Examples:

NaNO3 Sodium nitrate

K2SO4 Potassium sulfate

Al(HCO3)3 Aluminum bicarbonate or Aluminum hydrogen

carbonate

Learning Check

Match each set with the correct name:

1. Na2CO3 a) magnesium sulfite

MgSO3 b) magnesium sulfate

MgSO4 c) sodium carbonate

2. Ca(HCO3)2 a) calcium carbonate

CaCO3 b) calcium phosphate

Ca3(PO4)2 c) calcium bicarbonate

Mixed Practice! Name the following:

• Na2O

• CaCO3

• PbS2

• Sn3N2

• Cu3PO4

• HgF2