1. Ionic Compounds and Metals

2. Types of bonds
A chemical bond is the force that holds atoms together in a molecule.
Ionic bonds form when electrons are transferred between atoms.
Covalent bonds form when electrons are shared between atoms.

3. Electronegativity
Electronegativity is a measure of the attraction a bonded atom has for electrons.
Electronegativity increases from bottom to top and from left to right.

4. Formation of Ionic Bonds
If the electronegativity difference is large (a metal with a nonmetal) an ionic bond will form.
Ionic bonds are the strongest type of bond.
Substances resulting from ionic bonds are classified as crystalline solids.

5. Let’s Practice
Identify the type of bond (ionic or covalent) that will form between each pair of atoms.
Na and Cl
C and O
N and H
Ca and O
K and N
Mg and F

6. Example

7. Forming Ions
When neutral atoms gain or lose valence e- an ion is formed.
Ions are atoms with a charge
Cations have a positive charge (K+, Li+)
Anions have a negative charge (F-, I-)

8. Ions forming bonds
Cations are attracted to anions because of opposite charges.
“Opposites attract”

9. Why do ions form?
Ions form to attain a more stable electron configuration.
Remember that a Noble gas configuration is the most stable
Ne - ___ ___ ___ ___ ___
1s 2s 2p
All Noble Gases have a full octet (8 valence e-)

10. Noble Gases

11. Why do ions form? Na __ __ __ __ __ __ 1s 2s 2p 3s
Now Na+ looks like neon
Ne __ __ __ __ __
1s 2s p
All atoms are trying to have a Noble Gas electron configuration so, they will lose or gain electrons to get there

12. Why do ions form? F __ __ __ __ __ 1s 2s 2p F- __ __ __ __ __ 1s 2s 2p
Ne __ __ __ __ __

13. Review
Draw the dot notation for each element and the charge of its ion N S Ba Li

14. Ionic Bonds
Ionic bonds- the force that holds two oppositely (+ and -) charged particles together.
Ionic compounds contain ionic bonds and are neutral
Usually forms between a metal and a nonmetal

15. Forming Ionic Bonds

16. Forming Ionic Compounds
Write an equation showing how ionic compounds are formed for the following elements.
Na and I
Mg and O
Al and Cl

17. Properties of Ionic Compounds Shape
The Ionic bond produces unique characteristics for ionic compounds
Crystals are created by repeating patterns of cations and anions. This balances the forces between the ions.
This is called a crystal lattice

18. Properties of Ionic Compounds Physical Properties
Electrolytes (aqueous ions- Ions dissolved in water) conduct electricity
Solid ionic compounds DO NOT conduct electricity because the charges are locked in place

19. Properties of Ionic Compounds Physical Properties
Ionic solids are strong and hard to break apart
High Melting points
High Boiling points
Transition metals in the crystal give the ionic solid color.

20. Properties of Ionic Compounds Physical Properties
The solid ionic crystals are hard, rigid, and brittle
The strong forces between ions produce this property

21. Ionic Compounds
Ionic compounds are repeating patterns of the cation and anion.
The simplest ratio of ions involved is called a formula unit.
NaCl is the formula unit for table salt

22. Ions in Ionic Compounds
Monatomic ions- ions made of only one type of atom (Cl-, F-, Li+)
Polyatomic ions- ions made of at least two different types of ions (OH-, NH4+)
Cation + Anion  Ionic Compound

23. Writing formulas for ionic compounds
Binary ionic compounds contain a single cation and anion. Remember that the final compound must be neutral so the charges must balance.
Ca+2 Cl-  CaCl2

24. Cris-Cross method Record the ion symbol and charge
The # of the charge of the cation becomes the subscript for the anion and the # of the charge for the anion becomes the subscript for the cation. The #1 does not have to be recorded it is understood.
Al O-2  Al2O3

25. Cris-Cross method
Al2O3 is the formula units for aluminum oxide. The subscripts indicate how many ions are needed of each in order to balance the charges.

26. Try a few Potassium and Iodide Magnesium and chloride
Aluminum and bromide
Cesium and nitride

27. Naming Ionic Compounds
NaBr
Name the cation then the anion. Cations are always written first
Monatomic cations always keep their name. If the cation is an ion that may carry multiple charges then a roman numeral is used to indicate which charge the cation is carrying. [Fe+3 (III) and Fe+2 (II)].

28. Naming Ionic Compounds
The monatomic anion’s ending is changed to -ide. Fluorine is changed to Fluoride.
NaBr- sodium bromide
Fe3N2 – Iron (II) nitride

29. Let’s practice
CaCl2
K2O
CuCl2
Fe2O3

30. What about Polyatomic ions?
Al+3 and PO4-3  AlPO4
The same rules apply, however NEVER CHANGE A SUBSCRIPT THAT IS ALREADY THERE.
Polyatomic ions may also require () around them if there is a need for more than one to balance the charge