Ionic Bonding

1

• Ionic Bonding

2
Electron Configurations a Review and More
3
Keeping Track of Electrons

• The electrons responsible for the chemical
  properties of atoms are those in the outer energy
  level.
• Valence electrons - The s and p electrons in the
  outer energy level.
• Core electrons -those in the energy levels below.
  
• Basis for shorthand

4
Electron Configurations

• e- configuration notation
• Write complete e- configuration notation for
  elements 2, 6, 16
• He 1s2
• C 1s2 2s2 2p2
• S 1s2 2s2 2p6 3s2 3p4

5
Electron Configurations

• e- configuration notation (noble gas shortcut)
• Reminder this version uses a noble gas (group
  18) core instead of beginning at 1s

6
Electron Configurations

• e- configuration notation (noble gas shortcut)
• Write noble gas shortcut for elements 12, 21,
  35.
• Mg Ne 3s2
• Sc Ar 4s2 3d1
• Br Ar 4s2 4p5

7
Lewis dot diagrams

• lewis dot notation
• simplest notation, only shows valence e- (e- that
  may be lost, gained, or shared when chemical
  compounds are formed - they are from s p
  blocks)

8
Lewis Dot

• Lewis dot notation
• Draw dot diagrams for elements 1-10

9
Ion Formation
10
Ion Formation

• Valence electrons
• outer shell electrons that may be lost, gained,
  or shared when chemical compounds are formed

11
Ion Formation

• Octet rule
• atoms are most stable when they have a filled
  outer shell of valence e- (usually 8 e-)
• noble gases have this configuration without any
  help other atoms lose, gain, or share e- to
  fill their outer shell

12
Ion Formation

• Ions
• Atoms that have either gained or lost e-.
• Gain of e- gives a negative ion called an anion.
• Loss of e- gives a positive ion called a cation.

13
Ion Formation

• Ion examples
• The magnesium ion is Mg 2. How many p and e-
  does it have?
• 12 p, 10 e-

14
Ion Formation

• Ion examples
• The oxide ion is O 2-. How many p and e- does
  it have?
• 8 p, 10 e-

15
Ion Formation

• Ion examples
• An ion has 7 p and 10 e-. What ion is it?
• N3-

16
Ion Formation

• Ion examples
• An ion has 4 p and 2 e-. What ion is it?
• Be2

17
Keeping Track of Electrons

• Atoms in the same column
• Have the same properties because
• Have the same outer electron configuration.
• Have the same valence electrons.
• Group 2- Be, Mg, Ca, etc.-
• 2 valence electrons

18
Electron Dot diagrams

• A way of keeping track of valence electrons.
• How to write them
• Write the symbol.
• Put one dot for each valence electron
• Dont pair up until they have to

X
19
The Electron Dot diagram for Nitrogen

• Nitrogen has 5 valence electrons.
• First we write the symbol.

N

• Then add 1 electron at a time to each side.

• Until they are forced to pair up.

20
Write the electron dot diagram for
F Ne He

• Na
• Mg
• C
• O

21
Electron Configurations for Cations

• Metals lose electrons to attain noble gas
  configuration.
• They make positive ions.
• Na 1s22s22p63s1 - 1 valence electron
• Na 1s22s22p6 -noble gas configuration

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Electron Dots For Cations

• Metals will have few valence electrons

Ca
23
Electron Dots For Cations

• Metals will have few valence electrons
• These will come off

Ca
24
Electron Dots For Cations

• Metals will have few valence electrons
• These will come off
• Forming positive ions

Ca2
25
Electron Configurations for Anions

• Nonmetals gain electrons to attain noble gas
  configuration.
• They make negative ions.
• S 1s22s22p63s23p4 - 6 valence electrons
• S2- 1s22s22p63s23p6 -noble gas configuration.

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Electron Dots For Anions

• Nonmetals will have many valence .electrons.
• They will gain electrons to fill outer shell.

P
P3-
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Practice

• Use electron dot diagrams to show how the
  following form ions
• Al
• Cl
• C

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Stable Electron Configurations

• All atoms react to achieve noble gas
  configuration.
• Noble gases have 2 s and 6 p electrons.
• 8 valence electrons .
• Also called the octet rule.

Ar
29
Names of ions

• Cations keep the name of the metal
• Ca calcium
• Ca2 calcium ion
• Anions change ending to ide
• Cl Chlorine
• Cl1- chloride ion

30
Transition metals

• Form cations
• Hard to predict the charge
• Often will form more than 1 charge
• Cant form noble gas configuration
• Still try to fill up orbitals
• Some can make pseudo noble gas configurations
  with full orbitals

31
Polyatomic ions

• Groups of atoms that stick together as a unit,
  and have a charge
• (PO4)3- phosphate
• (CO3)2- carbonate
• (NH4) Ammonium
• (NO3) 1- Nitrate
• (NO2) 1- Nitrite
• Names often end in ate or ite

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Ionic Bonding

• Anions and cations are held together by opposite
  charges.
• This is the bond
• Ionic compounds are called salts.
• Simplest ratio is called the formula unit.
• The bond is formed through the transfer of
  electrons.
• Electrons are transferred to achieve noble gas
  configuration.

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Ionic Bonding
1-
1
Na
Cl
34
Ionic Bonding

• All the electrons must be accounted for!

Ca
P
35
Ionic Bonding
Ca
P
36
Ionic Bonding
Ca2
P
37
Ionic Bonding
Ca2
P
Ca
38
Ionic Bonding
Ca2
P3-
Ca
39
Ionic Bonding
Ca2
P3-
Ca
P
40
Ionic Bonding
Ca2
P3-
Ca2
P
41
Ionic Bonding
Ca
Ca2
P3-
Ca2
P
42
Ionic Bonding
Ca
Ca2
P3-
Ca2
P
43
Ionic Bonding
Ca2
Ca2
P3-
Ca2
P3-
44
Ionic Bonding
Ca3P2
Formula Unit
45
Practice

• Use electron dot diagrams to show how the
  following elements make an ionic compound and
  write the formula unit
• Mg and Cl

46
Practice

• Na and N

47
Practice

• Al and O

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Writing formulas

• The charges must add to 0
• Add the correct subscript to make them equal zero
• Na1 O2-
• Sr2 Cl1-
• Fe3 O2-
• Potassium bromide
• Beryllium fluoride

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Polyatomic ionic compounds

• (NH4) and N 3
• It will take three (NH4) to bond with
• One N 3
• You must have a neutral compound in ALL cases!
• So we write
• (NH4)3 N
• This says 3 ammonium ions bonded to one Nitride
  ion

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Ionic Compounds

• Made up of
• a positive and negative ion
• a cation and an anion
• a metal and a nonmetal
• Smallest repeating unit- formula unit

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Properties of Ionic Compounds

• Crystalline structure.
• A regular repeating arrangement of ions in the
  solid.
• Ions are strongly bonded.
• Structure is rigid.
• High melting points- because of strong forces
  between ions.

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Crystalline structure
3 dimension
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Ionic solids are brittle
54
Ionic solids are brittle

• Strong Repulsion breaks crystal apart.

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Crystal Structures

• The repeating unit is called the unit cell

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Do they Conduct?

• Conducting electricity is allowing charges to
  move.
• In a solid, the ions are locked in place.
• Ionic solids are insulators.
• When melted, the ions can move around.
• Melted ionic compounds conduct.
• First get them to 800ºC.
• Dissolved in water they conduct.