1. The Formation and Nature of Ionic Bonds

2. Formation of Ionic Compounds
iron + oxygen
sodium + chlorine

3. Formation of Sodium Ion
Sodium atom Sodium ion
Na  – e  Na +
( = Ne)
11 p p+
11 e e-

4. Chloride Ion     1 - : Cl  + e : Cl :     2-8-7 2-8-8 (= Ar)
unpaired electron octet
   
: Cl  e : Cl :
   
(= Ar)
17 p p+
17 e e-
ionic charge

5. Vocabulary Word
oxidation number = the positive or negative charge of a monoatomic ion

6. Formation of Ionic Compounds
the sodium ion and the chloride ion are attracted to each other, since they have opposite charges

7. 1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

9. Vocabulary Word
ionic bond = electrostatic force holding two oppositely charged particles together in an ionic compound; usually occurs between metals and non-metals; electrons are transferred

10. Ionic Compound Formation
the resulting ionic compound must be neutral (no NET charge).
positive and negative charges must be balanced
Ca (2 VE) forms a +2 cation
F (7 VE) forms a -1 anion
when Ca and F combine there must be 2 F for each Ca in the compound

11. Vocabulary Word
formula unit = simplest ratio of ions in an ionic compound; overall charge is always equal to zero

12. 1 +1 3 +3 5 -3 6 -2 7 -1
2 Valence Electrons
+2 Oxidation Number

13. Writing Formulas for Ionic Compounds
list the ions involved
if the oxidation numbers are equal, they combine 1:1
Na+1 Cl-1  NaCl
if the oxidation numbers are not equal, subscripts must be used to balance the charges
K+1 S-2  K2S

14. Try This Al+3 S-2 needs 2 aluminum ions for every 3 sulfide ions Al2S3
crisscross the charges and reduce to lowest terms

15. Vocabulary Word
polyatomic ion = an ion made of 2 or more atoms bonded together that act as a single unit with a net charge

16. Polyatomic Ions
the charge given to a polyatomic ion applies to the whole group
if more than one polyatomic ion is needed to balance the charges, parentheses are used and a subscript is written outside the parenthesis

17. Polyatomic Ions Mg+2 ClO3-1
2 chlorate ions are needed to balance each magnesium ion
Mg(ClO3)2

18. Chemical Nomenclature: a systematic way of naming compounds.

19. Rules for naming ionic compounds:
Name of the cation (+) first and the anion (-) second.
2. Cations (+) use the element name.
3. Anions (-) take their name from the root of the element name plus –ide.

20. Rules continued:
4. The transition metals can have more than one oxidation number.
The oxidation number of the transition elements needs to be written in Roman Numerals and placed in parenthesis.
The parenthesis need to be placed after the name of the transition metal.
Ex) FeO is Iron (II) Oxide

21. Rules Continued
5. If the compound contains a polyatomic ion, simply name the ion.

22. Name the following 11. NaBr Sodium Bromide 12. CaCl2 Calcium Chloride
13. KOH Potassium hydroxide
14. Cu(NO3)2 Copper (II) Nitrate
15. Ag2CrO4 Silver chromate

23. Properties of Ionic Compounds
the type of bond holding a compound together determines many of the physical properties of the compound
ionic compounds are packed in a repeating pattern to balance the forces of attraction and repulsion between the ions and form ionic crystal lattice

24. Each gray sodium ion is surrounded by yellow chloride ions.
Each chloride ion is surrounded by sodium ions.
Every ion interacts with multiple partners.

25. Vocabulary Word
Crystal Lattice: a three-dimensional arrangement of particles in an ionic solid where ions are surrounded by other ions of opposite charges

26. Ionic Bond Strength ionic bonds are relatively strong
it takes a lot of energy to disrupt the lattice
so ionic compounds:
have a high melting point
have a high boiling point

27. External Forces
when an external force is used to overcome the attractive forces in an ionic crystal lattice, it repositions ions with like charge too closely
the repulsive forces cause the crystal to crack so ionic compounds are brittle

28. Conducting Electricity
charged particles must be free to move within a material for it to conduct electricity
in the solid state ionic compounds are nonconductors
when melted (with heat) or dissolved in water ionic compounds are good conductors because the ions are free to move and conduct electricity (electrolyte)

29. Endothermic and Exothermic Reactions
during chemical reactions energy is either:
released (exothermic)
absorbed (endothermic)
the formation of ionic compounds is ALWAYS exothermic
the energy of the ionic compound formed is lower than the energy of the ions that formed it

30. Lattice Energy
the energy required to separate a mole of an ionic compound into its ions is called lattice energy
more negative values for lattice energy means the lattice holds together tighter (stronger forces of attraction btwn ions)

31. Lattice Energy
smaller ions can pack tighter and the resulting compounds have more negative lattice energies
ionic compounds made of ions with a greater difference in charge have more negative lattice energies