Ionic Bonding

1
Ionic Bonding

• Chapter 8

2
Forming Chemical Bonds

• Chemical bond force that holds two atoms
  together
• Can be formed from attraction b/t one atoms
  nucleus the others e-
• Can be formed from the attraction b/t cation
  anion
• Only valence e- involved
• (reactivity based on of valence e-)

3
Formation of a positive ion

4
Cations

• Formed from loss of valence e-
• Ne 1s22s22p6
• Na 1s22s22p63s1
• Na 1s22s22p6 (noble gas configuration)
• Ne 1s22s22p6
• Mg 1s22s22p63s2
• Mg2 1s22s22p6 (noble gas configuration)

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Formation of a negative ion

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Anions

• Formed from gain of valence e-
• Ar 1s22s22p63s23p6
• Cl 1s22s22p63s23p5
• Cl- 1s22s22p63s23p6 (noble gas configuration)
• Ar 1s22s22p63s23p6
• S 1s22s22p63s23p4
• S2- 1s22s22p63s23p6 (noble gas configuration)

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"GENEROUS"
NON-METALS
METALS
8
How do you know the charge?
Li
Be
B
C
2e-
6p
3p
4p
5p
1
IA
VIIA
VIIIA
3
2
IIA
IIIA
VIA
VA
IVA
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Formation Nature of Ionic Bonds

• Ionic bond electrostatic force that holds
  oppositely charge particles together
• Formed b/t metals nonmetals
• Formed from transfer of electrons
• Referred to as salts or oxides
• Formation of NaCl
• Overall charge on an ionic compound is always ZERO

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Metals combine with non-metals Metals lose
electrons to non-metals They then attract because
their charges will be opposite.
Metals
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Properties of Ionic Compounds

• Ions packed tightly to form crystal lattice
• High m.p. b.p.
• Lattice energy energy required to break ionic
  bond (high)
• Electrolytes ionic compound whose aqueous
  solution conducts electricity

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Whats an ion? Lets find out
Coil of wire
battery
_

_

compass
13
Switch is open. Nothing happening yet.
Coil of wire
battery
_

_

compass
Copper Chloride
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If copper atoms are going to the negative side,
what charge do they have?
What about the chlorine atoms?
Coil of wire
battery
_

_

compass
Copper Chloride
15
Since the atoms wandered towards each side, lets
call them IONS from the Greek word, ion, meaning
wanderer.
Coil of wire
battery
_

_

compass




Copper Chloride
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Also, since the positive side of a battery is
called the anode (way up), well call ions that
go towards it anions.
Since the negative side of a battery is called
the cathode (way down), well call ions that go
towards it cations.
_

anode
cathode
_

anode
cathode




Cations
Anions




Copper Chloride CuCl2
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Names Formulas for Ionic Compounds

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Ionic Formulas

• Formula unit simplest ratio of ions in an ionic
  compound
• Monatomic ion one-atom ion
• eg Na, Mg2, Cl-, O2-
• Charge of monatomic ion is its oxidation
• Determining formulas
• Write ions with charges
• Oxidation becomes subscript on other ion
  (criss-cross)
• Write formula (NO CHARGES!!!)
• Try sodium chloride

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Practice Makes Perfect

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Write formulas for compounds formed b/t

• potassium iodide
• magnesium chloride
• aluminum bromide
• cesium nitride
• barium sulfide

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Polyatomic Ions

• Polyatomic ion ion made of more than one atom
• eg NH4, NO3-, OH-, ClO4-
• Never change subscripts of atoms in polyatomic
  ions
• Memorize chart on p. 224
• Determining formulas
• Follow same procedures as before
• Use parentheses () when theres more than one
  polyatomic ion
• Try ammonium chloride

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These polyatomic ions match the charge of the
single element
-1
Ions with -1 charge perbromate BrO4-1 bromate
BrO3-1 bromite BrO2-1 hypobromite
BrO-1 perchlorate ClO4-1 chlorate
ClO3-1 chlorite ClO2-1 hypochlorite
ClO-1 periodate IO4-1 iodate
IO3-1 iodite IO2-1 hypoiodite
IO-1
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These polyatomic ions match the charge of the
single element
Ions with a -2 Charge sulfate SO4-2 sulfite
SO3-2 Ions with a -3 Charge phosphate
PO4-3 phosphite PO3-3
-3
-2
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Practice Makes Perfect

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Write formulas for compounds formed b/t

• sodium nitrate
• calcium chlorate
• aluminum carbonate
• potassium chromate
• magnesium sulfate

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Naming Compounds
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Oxyanions

• Oxyanion polyatomic ion containing oxygen
• One with more O ends ate
• eg sulfate SO42-, nitrate NO3-
• One with fewer O ends ite
• eg sulfite SO32-, nitrite NO2-

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Naming Ionic Compounds

• Name cation first
• Monatomic cations use elements name
• eg K potassium ion, Ba2 barium ion
• Monatomic anions use elements root name ide
• eg Cl- chloride ion, O2- oxide ion
• Some elements have more than one oxidation ?
  roman numeral used to indicate oxidation state
• eg Fe2 iron(II) ion, Fe3 iron(III) ion
• If compound contains polyatomic ion, simply name
  ion

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Examples 1 - Formulas to Names
1. Write the names of the ions
2. Determine the charge of the positive ion

• MgCl2

Im a monatomic ion
magnesium
chloride
If the positive ion has a fixed charge, you are
finished.
Final Name
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Examples 2- Formulas to Names
1. Write the names of the ions
2. Determine the charge of the positive ion

• LiCN

Im a polyatomic ion
lithium
cyanide
If the positive ion has a fixed charge, you are
finished.
Final Name
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Examples 3- Formulas to Names

• CuSO3

1. Write the names of the ions
0
-2
2. Determine the charge of the positive ion
Cu
SO3
2
x
X (- 2) 0
Im a polyatomic ion
You must know the charge on the sulfite ion is -2
The sum of the positive and negative charges must
equal zero
2 2
X 2
copper
sulfite
(II)
Final Name
Next
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Practice Makes Perfect

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Name the following compounds

• NaBr
• CaCl2
• KOH
• Cu(NO3)2
• Ag2CrO4

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Metallic Bonding

• Electron Sea Model all metal atoms in a
  metallic solid contribute their valence e- to
  form a sea of electrons
• e- not held by a specific atom ? they move freely
  ? delocalized e-
• Metallic bond attraction of metallic cations
  for delocalized e-

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Properties of metals

• High m.p. b.p. (attraction b/t cations e-)
• Malleable, ductile, lustrous
• Good conductors (delocalized e- move
  heat/electricity through rapidly)
• Alloy mixture of elements that has metallic
  properties
• eg steel