1. Ionic compounds

2. What is a bond?
A mutual electrical attraction between the nuclei and valence electrons of different atoms that binds them together.
Can be formed by atoms gaining, losing, or sharing electrons.
Why do atoms form chemical bonds?
To become more stable (lower potential energy)
ONLY valence electrons are used for bonding.

3. Ionic bonds
Atoms lose or gain electrons to satisfy octet (become more stable)
Form two kinds of ions—atom that has an electrical charge.
Cations—positively charged atoms.
Anions—negatively charged atoms

4. Periodic trends associated with ionic bonding
Ionization energy—energy required to remove an electron from the outer shell of an atom.
Electron affinity—the change in energy when an electron is added to the outer shell.
For bonding—High IE, high EA = less likely to give electrons = anion
Low IE, low EA = more likely to give electrons = cation

5. Formation of Cations Atoms that lose electrons: Examples: Metals
Low IE - does not require a ton of energy to take an e- away
Low EA - does not readily accept other e- into outer shell.
Examples: Metals
Li, Na, K, Be, Mg, Ca, etc.
Draw orbital diagrams for the following: Li Mg Al

6. Transition Metals
Form cations with different oxidation states (depends on what it’s bound to)
Titanium: [Ar]4s23d2
Can lose two electrons for Ti2+ or four electrons for Ti4+

7. Formation of Anions Atoms that gain electrons:
High IE—requires a ton of energy to take an e- away
High EA-readily accepts other e- into outer shell.
Examples: Halogens and nonmetals
F, N, O, Cl, etc.
Draw orbital diagrams of the valence shells of the following: F S Br

8. Write the oxidation states for the following elementsMg Li P Ca Ba I K O S Cl N F

9. Ionic Bonds Held together by electrostatic force
Electrostatic force—force of attraction between positively and negatively charged particles

10. Crystal lattice What is it?
a 3 dimensional geometric arrangement of particles where + and – ions surround each other
the ions are packed into a regular repeating pattern that balances the forces of attraction and repulsion between the atoms

11. Crystal lattice Na Cl
- In a solid state, ionic compounds are non-conductors,
ions must be free to move for a current to pass
through it
- In a liquid state (molten) or when dissolved in water
they are good conductors (ions are free to move)

12. Amorphous—particles are arranged randomly throughout the solid
Crystalline—particles pack in an organized fashion
Amorphous
Crystalline

13. Amorphous
Crystalline

14. Lattice energy
The energy released when 1 mol of an ionic compound is formed from gaseous ions.
Endothermic—energy has to be absorbed for the rxn to happen
Surroundings are colder
Exothermic—energy is released (Ex: -436 kJ/mol)
Surroundings feel warmer since energy is given off
Which is more stable?

15. Formation of ionic compounds is almost ALWAYS exothermic Why
Formation of ionic compounds is almost ALWAYS exothermic Why??? More stable with lower potential energy

16. Formulas
Formula unit - represents the most simple ratio of the ions in an ionic compound
The total number of e-‘s gained by the nonmetal must equal the number lost by the metal atoms
Oxidation states - give insight into how the atom will bond
Used to determine the formula for a compound

17. Polyatomic Ions Two or more atoms that together carry a charge
the charge given applies to the entire group of atoms
acts like an individual ion
if more than one polyatomic ion is required, use ( ) then subscript Ca(NO3)2
Example: Nitrate, NO3-1 and Ammonium, NH4+

18. Nomenclature What is it?? Rules for ionic nomenclature
The naming and writing of formulas for chemical compounds.
Rules for ionic nomenclature
1.) Cation is ALWAYS written first.
2.) Anion is ALWAYS written second.
3.) Use subscripts to cancel out charges
4.) Overall charge of the compound formed is always ZERO

19. Write the formulas for a compound formed by the following elements.
Practice
Write the formulas for a compound formed by the following elements.
K and Cl
Mg and Br
Li and O

20. Rules for ionic nomenclature
Write the name of the cation 1st using the elements name
Write the root word of the anion 2nd plus change the suffix to “ide”
Transition metals can have more than one ox. #
Write the elemental name then give ox. # as roman numeral in parenthesis.
Ex: iron (III) oxide
NEVER change the name of a polyatomic ion

21. Write the name of the following compounds:
Practice
Write the name of the following compounds:
MgCl2
CaCO3
MgSO4
KCN
NaOH

22. Write the formulas for the following compounds:
Practice
Write the formulas for the following compounds:
Magnesium Bromide
Sodium Nitrate
Calcium Carbonate
Palladium (II) Chloride