If you have been absent, view the class PowerPoint for Chapter 6. You should be able to view it directly on FB.

2. • OBJECTIVES:
–Determine the number of
valence electrons in an atom
of a representative element.
–Explain how the octet rule
applies to atoms of metallic
and nonmetallic elements.

3. • OBJECTIVES:
–Describe how cations form.
–Explain how anions form.
–Explain the electrical charge of
an ionic compound.

4. • OBJECTIVES:
–Describe how cations form.
–Explain how anions form.
–Explain the electrical charge of
an ionic compound.

5. • OBJECTIVES:
–Explain the electrical charge of
an ionic compound.
–Describe three properties of
ionic compounds.

6. • OBJECTIVES:
–Describe the arrangement of
atoms in a metal.
–Explain the importance of
alloys.

7. The Octet Rule
We learned that noble gases are unreactive in
chemical reactions
In 1916, Gilbert Lewis used this fact to
explain why atoms form certain kinds of ions
and molecules
The Octet Rule: in forming compounds,
atoms tend to achieve a noble gas
configuration; 8 in the outer level is stable
Each noble gas (except He, which has 2)
has 8 electrons in the outer level

8. Formation of Cations
• Metals lose electrons to attain a noble gas
configuration.
• They make positive ions (cations)

9. Electron Dots For Cations
• Metals will have few valence electrons
(usually 3 or less); calcium has only 2
valence electrons
Ca

10. Electron Dots For Cations
• Metals will have few valence electrons
• Metals will lose the valence electrons
Ca

11. Electron Dots For Cations
• Metals will have few valence electrons
• Metals will lose the valence electrons
• Forming positive ions
Ca 2+ This is named the
“calcium ion”.
NO DOTS are now shown for the cation.

12. Electron Configurations: Anions
• Nonmetals gain electrons to attain noble
gas configuration.
• They make negative ions (anions)

13. Electron Dots For Anions
• Nonmetals will have many valence electrons
(usually 5 or more)
• They will gain electrons to fill outer shell.
P 3- (This is called the “phosphide
ion”, and should show dots)

14. Stable Electron Configurations
• All atoms react to try and achieve a noble
gas configuration.
• 8 valence electrons = already stable!
• This is the octet rule (8 in the outer level is
particularly stable).
Ar

15. Octet Rule = atoms tend to gain, lose or share electrons so
as to have 8 electrons
C would like to Gain 4 electrons
N would like to Gain 3 electrons
O would like to Gain 2 electrons

17. Learning Check

A. X would be the electron dot formula for
1) Na 2) K 3) Al

B.  X would be the electron dot formula

1) B 2) N 3) P

18. Chemical bonds: an attempt to fill electron shells
1. Ionic bonds –
2. Covalent bonds –
3. Metallic bonds

19. IONIC BOND
bond formed between
two ions by the
transfer of electrons

20. Ionic Bonding —
Ionic Compounds
• Anions and cations are held together by
opposite charges (+ and -)
• Ionic compounds are called salts.
• The bond is formed through the transfer
of electrons (lose and gain)
• Electrons are transferred to achieve noble
gas configuration.

21. Ionic Bonding
Na Cl
The metal (sodium) tends to lose its one
electron from the outer level.
The nonmetal (chlorine) needs to gain one
more to fill its outer level, and will accept the
one electron that sodium is going to lose.

22. Ionic Bonding
Na Cl+ -
Note: Remember that NO DOTS
are now shown for the cation!

23. Ionic Bonding
Lets do an example by combining
calcium and phosphorus:
Ca P
• All the electrons must be accounted for, and
each atom will have a noble gas
configuration (which is stable).

24. Ionic Bonding
Ca P

25. Ionic Bonding
Ca 2+
P

26. Ionic Bonding
Ca 2+
P
Ca

27. Ionic Bonding
3-
Ca 2+
P
Ca

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

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

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

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

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

33. Ionic Bonding
= Ca3P2 Formula Unit
This is a chemical formula, which
shows the kinds and numbers of atoms in
the smallest representative particle of the
substance.
For an ionic compound, the smallest
representative particle is called a:
Formula Unit

34. Properties of Ionic Compounds
1. Crystalline solids - a regular repeating
arrangement of ions in the solid: Fig. 5,
page 162
– Ions are strongly bonded together.
– Structure is rigid.
2. High melting points
• Coordination number- number of ions of
opposite charge surrounding it

35. - Page 162
Coordination Numbers:
Both the sodium
NaCl and chlorine have 6
Both the cesium
CsCl and chlorine have 8
Each titanium has
TiO2 6, and each oxygen
has 3

36. Do they Conduct?
• Conducting electricity means allowing
charges to move.
• In a solid, the ions are locked in place.
• Ionic solids are insulators.
• When melted, the ions can move around.
3. Melted ionic compounds conduct.
– NaCl: must get to about 800 ºC.
– Dissolved in water, they also conduct (free to
move in aqueous solutions)

37. Formation of Ions from Metals
Ionic compounds result when metals react with
nonmetals
Metals lose electrons to match the number of valence
electrons of their nearest noble gas
Positive ions form when the number of electrons are
less than the number of protons
Group 1 metals → ion 1+
Group 2 metals → ion 2+
• Group 13 metals → ion 3+

38. Formation of Sodium Ion
Sodium atom Sodium ion
Na • – e− → Na +
2-8-1 2-8 ( = Ne)
11 p+ 11 p+
11 e- 10 e-
0 1+

39. Formation of Magnesium Ion
Magnesium atom Magnesium ion
•
Mg • – 2e− → Mg2+
2-8-2 2-8 (=Ne)
12 p+ 12 p+
12 e- 10 e-
0 2+

40. Some Typical Ions with Positive
Charges (Cations)
Group 1 Group 2 Group 13
H+ Mg2+ Al3+
Li+ Ca2+
Na+ Sr2+
K+ Ba2+

41. Learning Check
A. Number of valence electrons in aluminum
1) 1 e- 2) 2 e- 3) 3 e-
B. Change in electrons for octet
1) lose 3e- 2) gain 3 e- 3) gain 5 e-
C. Ionic charge of aluminum
1) 3- 2) 5- 3) 3+

42. Solution
A. Number of valence electrons in aluminum
3) 3 e-
B. Change in electrons for octet
1) lose 3e-
C. Ionic charge of aluminum
3) 3+

43. Learning Check
Give the ionic charge for each of the following:
A. 12 p+ and 10 e-
1) 0 2) 2+ 3) 2-
B. 50p+ and 46 e-
1) 2+ 2) 4+ 3) 4-
C. 15 p+ and 18e-
2) 3+ 2) 3- 3) 5-

44. Ions from Nonmetal Ions
In ionic compounds, nonmetals in 5A, 6A, and
7A gain electrons from metals
Nonmetals add electrons to achieve the octet
arrangement
Nonmetal ionic charge:
3-, 2-, or 1-

45. Fluoride Ion
unpaired electron octet
•• •• 1-
:F• + e− : F:
•• ••
2-7 2-8 (= Ne)
9 p+ 9 p+
9 e- 10 e-
0 1-
ionic charge

46. Ionic Bond
• Between atoms of metals and nonmetals
with very different electronegativity
• Bond formed by transfer of electrons
• Produce charged ions all states. Conductors
and have high melting point.
• Examples; NaCl, CaCl2, K2O

48. Ionic Bonds: One Big Greedy Thief Dog!

50. Naming Ionic Compound
• All names have a predictable pattern.
• Name of the cation first, then the anion.
• Cation name remains the same
• Anion name will end in –ide.
• EXAMPLE: Sodium Chloride
• COMMON ANIONS
• Fluorine  Fluoride
• Chlorine  Chloride
• Bromine  Bromide
• Iodine  Iodide
• Oxygen  Oxide
• Sulfur  Sulfide
• Nitrogen  Nitride
• Phosphorus  Phosphide

51. Section A: Complete the chart using a periodic table to help you.

52. Answer these questions:
NEGATIVE
An atom that gains one or more electrons will have a ____________________
charge.
POSITIVE
An atom that loses one or more electrons will have a ____________________
charge.
ION
An atom that gains or loses one or more electrons is called an ____________.
CATION
A positive ion is called a ______________ and a negative ion is called an
ANION
_______________.
“Cat-Eye-
“An-Eye- On”
On”

53. What is an ionic bond?
ELECTRONS
Atoms will transfer one or more ________________ to another to form the bond.
COMPLETE
Each atom is left with a ________________ outer shell.
METAL
An ionic bond forms between a ___________ ion with a positive charge and a
NONMETAL
________________ ion with a negative charge.
Example B1: Sodium + Chlorine Example B2: Magnesium + Iodine

54. Example B3: Potassium + Iodine Example B4: Sodium + Oxygen
Example B5: Calcium + Chlorine Example B6: Aluminum + Chlorine

55. COVALENT BOND
bond formed by the
sharing of electrons

56. Covalent Bond
• Between nonmetallic elements of similar
electronegativity.
• Formed by sharing electron pairs
• Stable non-ionizing particles, they are not
conductors at any state
• Examples; O2, CO2, C2H6, H2O, SiC

58. Bonds in all the
polyatomic ions
and diatomics
are all covalent
bonds

59. NONPOLAR
COVALENT BONDS
when electrons are
shared equally
H2 or Cl2

60. 2. Covalent bonds- Two atoms share one or more pairs of outer-shell
electrons.
Oxygen Atom Oxygen Atom
Oxygen Molecule (O2)

61. POLAR COVALENT
BONDS
when electrons are
shared but shared
unequally
H2O

62. Polar Covalent Bonds: Unevenly
matched, but willing to share.

63. - water is a polar molecule because oxygen is more
electronegative than hydrogen, and therefore electrons
are pulled closer to oxygen.

64. Polyatomic Ions
• Covalently bonded group of atoms that has a
positive or negative charge and acts as a unit.
COMMON POLYATOMIC IONS
• Ammonium -- NH4 • Phosphate -- PO4
• Hydroxide -- OH • Chromate -- CrO4
• Nitrate -- NO3 • Silicate -- SiO3
• Sulfate -- SO4 • Acetate -- C2H3O2
• Carbonate -- CO3 • Peroxide -- O2

65. What is a covalent bond?
SHARE
Atoms ___________ one or more electrons with each other to form the bond.
COMPLETE
Each atom is left with a ________________ outer shell.
NONMETAL
A covalent bond forms between two _________________.
Example C1: Hydrogen + Hydrogen Example C2: 2 Hydrogen + Oxygen

66. Example C3: Chlorine + Chlorine Example C4: Oxygen + Oxygen
Example C5: Carbon + 2 Oxygen Example C6: Carbon + 4 Hydrogen

67. METALLIC BOND
bond found in
metals; holds metal
atoms together
very strongly

68. Metallic Bonds are…
• How metal atoms are held together
in the solid.
• Metals hold on to their valence
electrons very weakly.
• Think of them as positive ions
(cations) floating in a sea of
electrons

69. Sea of Electrons
• Electrons are free to move through the
solid.
• Metals conduct electricity.
+ + + +
+ + + +
+ + + +

70. Metals are Malleable
• Hammered into shape (bend).
• Also ductile - drawn into wires.
• Both malleability and ductility
explained in terms of the mobility
of the valence electrons

71. Due to the mobility of the
Notice
valence electrons, metals have: that the
ionic
1) Ductility and 2) Malleability
crystal
breaks
due to ion
repulsion!

72. Malleable
+ + + +
Force
+ + + +
+ + + +

73. Malleable
• Mobile electrons allow atoms to slide by,
sort of like ball bearings in oil.
+ + + +
Force
+ + + +
+ + + +

74. Ionic solids are brittle
Force + - + -
- + - +
+ - + -
- + - +

75. Ionic solids are brittle
• Strong Repulsion breaks a crystal apart, due
to similar ions being next to each other.
+ - + -
Force
- + - +
+ - + -
- + - +

76. Metallic Bonds: Mellow dogs with plenty
of bones to go around.

77. Ionic Bond, A Sea of Electrons

78. Alloys
• We use lots of metals every day, but
few are pure metals
• Alloys are mixtures of 2 or more
elements, at least 1 is a metal
• made by melting a mixture of the
ingredients, then cooling
• Brass: an alloy of Cu and Zn
• Bronze: Cu and Sn

79. Why use alloys?
• Properties are often superior to the pure
element
• Sterling silver (92.5% Ag, 7.5% Cu) is harder
and more durable than pure Ag, but still soft
enough to make jewelry and tableware
• Steels are very important alloys
– corrosion resistant, ductility, hardness, toughness,
cost

80. Metals Form Alloys
Metals do not combine with metals. They form
Alloys which is a solution of a metal in a metal.
Examples are steel, brass, bronze and pewter.