1. Ionic Compounds Chapter 8
I will define a chemical bond
I will describe how ions form
I will identify ionic bonding and the characteristics of ionic compounds
I will name and write chemical formulas for ionic compounds
I will relate metallic bonds to the characteristics of metals

2. Forming Chemical Bonds
I will define chemical bond
I will relate chemical bond formation to electron configuration
I will describe the formation of positive and negative ions
Vocabulary: chemical bond, cation, anion

3. Chemical Bond A force that holds two atoms together Form in two ways:
By the attraction between a positive nucleus and negative electrons
By the attraction between a positive ion and a negative ion
Recall:
Valence electrons are involved in the formation of chemical bonds between 2 atoms
Atoms want 8 valence electrons so they have a stable electron structure (helium only needs 2)

5. Formation of Positive Ions
Positive ions form when an atom loses one or more valence electrons in order to attain a full outer shell
Cation
A positively charged ion
atom + ionization energy = ion+ + electron(s)

6. Which Elements Form Positive Ions?
Transition Metals (DIFFICULT to predict)
Outer energy level ns2 (in general)
L R atoms of each element are also filling in the d sublevel
Commonly lose their 2 valence electrons (form+2 ions)
Also possible for d electrons to be lost
Allows them to form +3 ions or greater
Group 1A
Lose 1 electron
Form +1 ions
Group 2A
Lose 2 electrons
Form +2 ions
Group 3A (a few)
Lose 3 electrons
Form +3 ions

7. Formation of Negative Ions
Negative ions form when an atom gains one or more valence electrons in order to attain a full outer shell
Anion
A negatively charged ion
atom + electron(s) = ion-- + electron affinity

8. Which Elements Form Negative Ions?
Nonmetals
Gain the number of electrons that when added to their valence electrons, equals 8
The number of electrons gained corresponds to their negative charge
Ex gain 2 electrons = form ions
To designate an anion, the ending –ide is added to the root name of the element
Ex NaCl = sodium chloride
Some nonmetals can gain or lose other numbers of electrons to form an octet
Ex phosphorous
Gain 3 electrons Or
Lose 5 electrons
MORE LIKELY to GAIN 3!!

9. Review- Ions that form
Look at electron configurations (valence electrons)
Metals lose electrons (+ ions)
Nonmetals gain electrons (- ions)
Typical charges of ions that form

10. The Formation and Nature of Ionic Bonds
I will describe the formation of ionic bonds
I will account for many of the physical properties of an ionic compound
I will discuss the energy involved in the formation of an ionic bond
Vocabulary: ionic bond, electrolyte, lattice energy

11. Formation of an Ionic Bond
The electrostatic force that holds oppositely charged particles together (opposite charge attraction)
Ionic Compound
Compounds that contain ionic bonds
Examples:
Oxides
Formed if ionic bonds are made between metals and the nonmetal oxygen
Salts
Most other ionic compounds

12. Formation of an Ionic Bond
Binary Compounds
Contain ONLY 2 different elements
Contain:
Metallic cation
Nonmetallic anion
Which compound is Binary?
MgO CaSO4

13. Formation of an Ionic Bond
The number of electrons lost must EQUAL the number of electrons gained
Aka: the overall charge on one unit of the compound must be ZERO
Example 1:
Na and Cl
1 Na ion (+1) + 1 Cl ion (-1) = (+1) + (-1) = 0
NaCl
Example 2:
Ca and F
1 Ca ion (+2) + 1 F ion (-1) + 1 F ion (-1) = (+2) + (-1) + (-1) = 0
CaF2

14. Properties of Ionic Compounds
Chemical bonds that occur btwn atoms determine physical properties
Ionic compounds (cations + anions)
Regular repeating patterns
Balance forces of attraction/repulsion
Called ionic crystal
1-to-1 ratios of ions produce a cubic crystal
Ex. salt

15. Conductivity Demonstration
. Do ionic compounds conduct electricity?
** First…what do you need to conduct electricity??
You need freely moving charged particles.
Solid –
Aqueous solution –
Liquid –
do not conduct…why not?
do conduct…why?
do conduct…why?
*** electrolyte: an ionic compound whose aqueous solution conducts an electric current

16. Properties of Ionic Compounds
Crystal Lattice structure – 3D geometric arrangement of ions (positive to negative)
Makes them hard – strong bonds
Makes them brittle – attracted only to opposite charges/repelled by like charges
Have high melting/boiling points

17. Properties of Ionic Compounds
Lattice Energy
Energy required to separate 1 mole of ions of an ionic compound
Also the energy given off when the ions bond
I think of this as “ionic bond energy” – how strong the bond is…
*Charge – the larger the charge, the larger the lattice energy
Size – the larger the radius, the smaller the lattice energy
NaBr, CaCl2, KI, MgO, CaO, BaI2, RbI (rank)
RbI < KI < BaI2 < CaCl2 < CaO < MgO
RbI = +1, large r + sm charge = smallest LE
KI = +1, small r + sm charge = sm LE
BaI2 = +2, large r + large charge = med LE
CaCl2 = +2, -2 large r + large charge = med LE
CaO = +2, large r + large charge = lg LE
MgO = +2, large r + large charge = 1g LE

18. Names and Formulas for Ionic Compounds
I will write formulas for ionic compounds and oxyanions
I will name ionic compounds and oxyanions
Vocabulary: formula unit, monatomic ion, oxidation number, polyatomic ion, oxyanion

19. Metallic Bonds and Properties of Metals
I will describe a metallic bond
I will explain the physical properties of metals in terms of metallic bonds
I will define and describe alloys
Vocabulary: electron sea model, delocalized electrons, metallic bond, alloy