1. Valence Electrons, Ions, and Lewis Dot Diagrams
Unit 4

2. Keeping Track of Electrons
The electrons responsible for the chemical properties of atoms are those in the outer energy level.
Valence electrons
Valence electrons - The s and p electrons in the outer energy level.
Core electrons -those in the energy levels below.

3. Keeping Track of Electrons
Atoms in the same column
Have the same outer electron configuration.
Have the same valence electrons.
Easily found by looking up the group number on the periodic table.
Group 2A - Be, Mg, Ca, etc.-
2 valence electrons

4. Xe Lewis Dot diagrams A way of keeping track of valence electrons.
How to write them
Write the symbol.
Put one dot for each valence electron
Don’t pair up until they have to Xe

5. The Lewis 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 Lewis dot diagram forNa Mg C O F Ne He

7. Electron Configurations for Cations
Metals lose electrons to attain noble gas configuration.
They make positive ions.
If we look at electron configuration it makes sense.
Na 1s22s22p63s1 - 1 valence electron
Na+ 1s22s22p6 -noble gas configuration

8. Electron Dots For Cations
Metals will have few valence electrons Ca

9. Electron Dots For Cations
Metals will have few valence electrons
These will come off Ca

10. Electron Dots For Cations
Metals will have few valence electrons
These will come off
Forming positive ions
Ca+2

11. Electron Configurations for Anions
Nonmetals gain electrons to attain noble gas configuration.
They make negative ions.
If we look at electron configuration it makes sense.
S 1s22s22p63s23p4 - 6 valence electrons
S-2 1s22s22p63s23p6 -noble gas configuration.

12. Electron Dots For Anions
Nonmetals will have many valence .electrons.
They will gain electrons to fill outer shell. P
P-3

13. 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

14. +1 +2 +3 -3 -2 -1

15. Unit 4: Chapter 8
Ionic Bonding

16. +1 +2 +3 -3 -2 -1

17. 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.

18. Crystalline structure

19. Ionic Bonding
Anions and cations are held together by opposite charges.
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.

20. 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.

21. Ionic solids are brittle+ -

22. Ionic solids are brittle
Strong Repulsion breaks crystal apart. + - + - + - + -

23. Ionic Bonding Na Cl

24. Ionic Bonding
Na+
Cl-

25. Ionic Bonding
All the electrons must be accounted for! Ca P

26. Ionic Bonding Ca P

27. Ionic Bonding
Ca+2 P

28. Ionic Bonding
Ca+2 P Ca

29. Ionic Bonding
Ca+2
P-3 Ca

30. Ionic Bonding
Ca+2
P-3 Ca P

31. Ionic Bonding
Ca+2
P-3
Ca+2 P

32. Ionic Bonding Ca
Ca+2
P-3
Ca+2 P

33. Ionic Bonding Ca
Ca+2
P-3
Ca+2 P

34. Ionic Bonding
Ca+2
Ca+2
P-3
Ca+2
P-3

35. Ionic Bonding
Ca3P2
Formula Unit

36. Naming ions We will use the systematic way.
Cation- if the charge is always the same (Group A) just write the name of the metal.
Examples
Sodium ion = Na+
Barium ion = Ba2+
Silver ion = Ag+
Zinc ion = Zn2+

37. Naming Anions Anions always have the same charge.
Change the element ending to – ide
Examples
Fluorine as an ion= F-1 fluoride
Chlorine as an ion= Cl- chloride
Oxygen as an ion= O2- oxide

38. Name these Cl-1 N-3 I-1 S-2 Chloride ion Nitride ion Iodide ion
Sulfide ion

39. Write these Oxide ion Fluoride ion Phosphide ion Strontium ion O2- F-
Sr2+

40. Naming Binary Ionic Compounds
Binary Compounds - 2 elements.
Ionic - a cation and an anion.
To write the names just name the two ions.
Easy with Representative elements (Group A)
NaCl = Na+ Cl- = sodium chloride
MgBr2 = Mg+2 Br- = magnesium bromide

41. Writing Formulas The charges have to add up to zero.
Get charges on pieces.
Charges for Cations come from the periodic table.
If it is a transition metal, the charge is the roman numeral
Anions from the periodic table.
Criss- Cross the charges to determine subscripts

42. ( only the numbers, not the signs)
The Criss-Cross Rule
Write the formula for calcium chloride.
Calcium is Ca+2
Chloride is Cl-1
Criss Cross the charges to determine the subscripts
Ca+2 Cl-1
( only the numbers, not the signs)
ANSWER: CaCl2

43. Naming ions with Transition Metals
Transition metals can have more than one type of charge.
Indicate the charge with roman numerals in parenthesis.
Examples
Ni+2 = nickel (II) ion
Ni+ = nickel (I) ion

44. Naming Binary Ionic Compounds
Write the formulas for each the following
CrN
Sc3P2
PbO
PbO2
Chromium (III) nitride
Scandium (II) phosphide
Lead (II) oxide
Lead (IV) oxide

45. Naming Binary Ionic Compounds with Transition Metals
The problem comes with the transition metals.
Need to figure out their charges.
The compound must be neutral.
same number of + and – charges.
Use the anion to determine the charge on the positive ion.

46. Naming Binary Ionic Compounds
Write the name of CuO
Need the charge of Cu
O is -2
copper must be +2
ANSWER: Copper (II) oxide

47. ANSWER: Cobalt (III) chloride
Name CoCl3
Cl is -1
there are three of them = -3
Co must be +3
ANSWER: Cobalt (III) chloride

48. Naming Binary Ionic Compounds
Write the name of Cu2S.
Since S is -2, the Cu2 must be +2, so each one is +1.
ANSWER: copper (I) sulfide
Fe2O3
Each O is x -2 = -6
2 Fe must = +6, so each is +3.
ANSWER: iron (III) oxide

49. Write the formulas for these
Li2S
SnO
SnO2
MgF2
FeP
Fe2P3
Lithium sulfide
tin (II) oxide
tin (IV) oxide
Magnesium fluoride
Iron (III) phosphide
Iron (III) sulfide

50. Polyatomic ions Groups of atoms that stay together and have a charge.
You must memorize these by the midterm
Nitrate NO3-1
Hydroxide OH-1
Sulfate SO4-2
Phosphate PO4-3
Ammonium NH4+1

51. Write the formulas for these
Ammonium chloride
ammonium sulfide
barium nitrate
Copper (II) sulfate
gallium nitrate

52. Ternary Ionic Compounds
NaNO3
CaSO4
CuSO3
(NH4)2O

53. Ternary Ionic Compounds
LiCN
Fe(OH)3
(NH4)2CO3
NiPO4

54. Things to look for If cations have (), the number is their charge.
If not it only has 1 charge, look on the periodic table
If anions end in -ide they are probably off the periodic table (Monoatomic)
If anion ends in -ate or -ite it is polyatomic

55. Metallic Compounds

56. Metallic Bonds How atoms are held together in the solid.
Metals hold onto there valence electrons very weakly.
Think of them as positive ions floating in a sea of electrons.

57. + Sea of Electrons Electrons are free to move through the solid.
Electrons are said to be “delocalized”
Metals conduct electricity. +

58. Properties of Metallic Compounds
Metal ions bonded together
Can be atoms of different metals
Hammered into shape (bend).
Ductile - drawn into wires.
Melting and boiling points vary (based on metal)
Good conductors of electricity as a solid

59. Malleable +

60. Malleable
Electrons allow atoms to slide by. + + + + + + + + + + + +