1. Ionic & Metallic Bonding
Chapter 7

2. 7.1 Ions Ions are atoms that have gained or lost electrons….
Have a net electrical charge
Cations & Anions
Valence electrons are lost when cations are formed
Electrons are gained by the valence shell when anions are formed.

3. Valence Electrons & Core Electrons
Ve’s are the outermost electrons
In the highest s and p sublevels
Core electrons are the remaining inner electrons
1s1 1s2 2s2 2p s2 2s2 2p s2 2s2 2p4
1s2 2s2 2p6 3s2 3p5 1s2 2s2 2p6 3s2 3p6 4s1

4. Valence electrons
Number of valence electrons largely determines properties of the element and its group
Elements within a group have the same number of valence electrons…Why?
Number of ve’s indicated by the group A group numbers, IA, IIA, IIIA, etc.
Or count left to right, skipping transition metals

5. Valence Electrons
1s s22s22p s22s22p s22s22p4

6. Lewis (Electron Dot) Structures
Valence electrons represented as dots

7. What is the octet rule?
Noble gases are extremely unreactive, i.e. very stable
When forming ions or compounds, representative elements (Group A) gain, lose, or share electrons in order to achieve a noble gas electron configuration
i.e. an octet, ns2np6

8. Metals vs. Nonmetals Metals tend to give up ve’s to achieve an octet
Nonmetals tend to gain or share ve’s to achieve an octet

9. Formation of Cations Na∙ → Na+ + e-
When Na loses its valence electron, there is an octet in the next lowest energy level
Using electron dot (Lewis) structures…
Na∙ → Na+ + e-

10. Formation of Cations
The electron configuration of the sodium ion is the same as that of a neon atom.

11. Transition Metals Do not follow the octet rule
“Pseudo-noble gas” configuration

12. Formation of Anions
Non-metals tend to gain ve’s to achieve an octet (noble gas e- configuration)

13. Formation of Anions
Using electron dot (Lewis) structures…

14. Formation of Anions
Both a chloride ion and the argon atom have an octet of electrons in their highest occupied energy levels.

15. How can you predict the charge of a monatomic ion?
Determine number of ve’s
Representative elements will gain or lose the least number of ve’s to achieve an octet
Predict the charge of the aluminum ion.

16. Can you do it? Use the octet rule to predict the charge B and S ions
How many valence electrons does it have?
Is it a metal or non-metal?
Will it gain or lose electrons?
If so, how many?
Write an equation using Lewis structures to show the formation of
The boron ion (Examples pp )
The sulfide ion (Examples pp )

17. Common Anions

18. 7.2 Ionic Compounds
If ionic compounds are composed of (+) and (-) ions, what type of elements are most likely to be found in them?
What types of elements form cations?
What types of elements form anions?
Usually composed of a metal and non-metal

19. Ionic Bonds & Ionic Compounds
Ionic bonds are electrostatic forces that hold cations and anions together
Ionic compounds are composed of cations and anions
Are electrically neutral

20. Ionic Bonds
Electrostatic forces of attraction between oppositely charged ions
Very strong bonds

21. Formula Unit Chemical formula for an ionic compound
Lowest whole number ratio of ions in the compound producing an electrical neutrality
What is the formula unit for…
Sodium chloride
Magnesium chloride
Sodium sulfide
Magnesium oxide

22. What are the properties of ionic compounds?
Solids
Brittle
High melting points
Evidence of very strong bonds
3D arrangement of ions
Coordination number
Electrolytes (conduct electric current when dissolved in water or molten

23. Crystalline Solids: Specific 3D Arrangement of Ions
“crystal lattice”

24. Coordination Number
Number of ions surrounding an oppositely charged ion

25. High melting temperatures (mp)
Because ionic bonds are very strong, it takes much energy to break them
Therefore, their mp’s are high

26. Sample mp’s of ionic compounds
Compound Name
Formula Unit
mp (ºC)
NaCl
801 (1473 F)
MgO
2852 (5165 F)
LiF
845 (1553 F)
Sr(NO3)2
570 (1058 F)
KNO3
334 (633 F)

27. Electrolytes Conduct electricity when dissolved or in a molten state
Electrical current is a movement of charge
Because ions are free to move in the molten or aqueous state

28. Electrolytes
Substances that conduct electrical current when dissolved (aqueous state)
Include ionic substances and some non-ionic (molecular) substances
Strength of electrolyte corresponds to degree of dissociation or ion formation when in water

29. Electrolytes
Strong electrolytes fully dissociate into ions when dissolved in water
Weak electrolytes partially dissociate
Non-electrolytes do not form ions when dissolved in water
most non-ionic substances
E.g. sugar (C12H22O11)

30. 7.3 Bonding in Metals: Structure of Metals
“Electron sea” model of metals
valence electrons are free to move about in metals
Metallic bonds: attraction between metal cations and core electrons of other cations

31. Metallic Bond Cations are attracted to electrons of other atoms
Valence electrons are free to move from atom to atom

32. Properties of Metals are due to the Structure of Metals
Ductility
Malleability
High electrical conductivity
Luster
High thermal conductivity
Electron sea model of metals

33. Compare Properties of Metals and Ionic Compounds
Property
Metals
Ionic Compounds
Malleability & ductility
High
Brittle
Electrical conductivity as solid
None
Luster
Low or none
Thermal conductivity

34. Structure of Metals and Ionic Cpds Explains Their Different Properties

35. Crystal Structure of Metals
Metal atoms arranged in orderly, compact patterns
Unit Cell & Crystal Lattice

36. Alloys Homogeneous mixtures of which at least one component is a metal
Alloys are examples of solid solutions
Have superior properties to the pure metal,
hardness, tensile strength, durability, etc.

37. Some bicycle frames are made of titanium alloys that contain aluminum and vanadium.

38. Steels are Alloys
There are many alloys of steel used for different applications
Vocational & Professional Opportunities…
Metallurgy & metallurgical engineering
Welding & welding engineering