Electron Transfer Dot Structures

1
Electron TransferDot Structures

• Ionic Compounds

2
Keeping Track of Electrons

• The electrons responsible for the chemical
  properties of atoms are those in the outer energy
  level.

3
Keeping Track of Electrons

• Atoms in the same column have the same valence
  electrons.
• Easily found by looking up the group number on
  the periodic table.

4
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
5
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.

6
Write the electron dot diagram for

• Na
• Mg
• C
• O
• F
• Ne
• He

7
Electron Dots For Cations

• Metals will have few valence electrons

Ca
8
Electron Dots For Cations

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

Ca
9
Electron Dots For Cations

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

Ca2
10
Electron Dots For Anions

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

P
P-3
11
Stable Octets

• All atoms react to achieve noble gas
  configuration.
• 8 valence electrons .
• Also called the octet rule.

Ar
12
Ionic Bonding

• The bond is formed through the transfer of
  electrons.
• Electrons are transferred to achieve noble gas
  configuration.
• Anions and cations are held together by opposite
  charges.

13
Ionic Bonding
Na
Cl
14
Ionic Bonding
-

Na
Cl
15
Counting Electrons

• During the formation of an ionic compound the
  total number of electrons lost (by cations) must
  equal the total number of electrons gained (by
  anions).

16
Ionic Bonding

• All the electrons must be accounted for, total
  lost total gained!

Ca
P
17
Ionic Bonding
Ca
P
18
Ionic Bonding
Ca2
P
19
Ionic Bonding
Ca2
P
Ca
20
Ionic Bonding
Ca2
P-3
Ca
21
Ionic Bonding
Ca2
P-3
Ca
P
22
Ionic Bonding
Ca2
P-3
Ca2
P
23
Ionic Bonding
Ca
Ca2
P-3
Ca2
P
24
Ionic Bonding
Ca
Ca2
P-3
Ca2
P
25
Ionic Bonding
Ca2
Ca2
P-3
Ca2
P-3
26
Ionic Bonding
2
Ca
-3
P
Ca
2
2
Ca
-3
P
27
Ionic Bonding
Ca3P2
Formula Unit