1. Ions and Ionic Bonds

2. Review
Octet Rule
Atoms typically gain or lose valence e- so they will have the same e- configuration as a noble gas.
Most noble gases have 8 valence electrons.
Helium has only 2 valence electrons.

3. The Octet Rule 1 valence electron 8 valence electrons Na Ne

4. The Octet Rule 8 valence electrons 7 valence electrons Cl Ar

5. The Octet Rule 2 valence electrons He 2 valence electronsLi

6. Ionic Bonds
Ionic bonds are a type of chemical bond based on electrostatic forces between two oppositely-charged ions.
It is basically the transfer of one electron from one atom to another

7. Ionic Bonds
An ion is an atom or group of atoms that have a charge. Atoms normally have a neutral charge because most often they have the same number of electrons and protons. They become ions by the loss or addition of one or more electrons. This process is called ionization.

8. Ionic Bonds
An ion that has more electrons than protons is called an anion, and an ion that has fewer electrons than protons is called a cation.

9. Ionic Bonds
The name ion was given by a man named Michael Faraday, which comes from a Greek word meaning “to go” or “a goer”.
The word anion comes from the Greek word meaning (a thing) “going up” and cation means (a thing) “going down”.

10. Ionic Compounds
Ionic compound (salt) – compound made of cations and anions.
cations are formed from metals
anions are formed from non-metals
Ionic bond – the force that holds an ionic substance together.

11. Ionic Bonding Na Cl + -

12. Ionic bonds Occurs when:
1. a metal atom loses an electron and becomes a positive ion
2. a non-metal atom gains the electron and becomes a negative ion
3. the positive and negative attract each other and form a bond

13. Ionic Bonding + -
IMPORTANT: Although the ions in a salt are charged, the compound as a whole is not.

14. How do ionic bonds form Use the criss-cross method
Step 1- Identify the metal and non-metal
Step 2- Write the symbols
Step 3- write the charges
Step 4- cross over the charges
Step 5- remove the charge (+ -)
Step 6- simplify the numbers and get rid of 1’s
NOTE: THE OVERALL CHARGE ON IONIC FORMULAS SHOULD ALWAYS EQUAL ZERO!!!!!!

15. Ionic Formulas
Chemical formula – indicates the number and type of atoms in a substance.
H2O
2 hydrogen atoms + 1 oxygen atom
NaNO3
1 sodium ion + 1 nitrogen atom + 3 oxygen atoms
Formula unit – lowest whole-number ratio of ions in a compound.
The formula unit for table salt is NaCl.
1 unit of Na+ ions per 1 unit of Cl- ions.
Formula does not show the charges of the ions.

16. Ionic Formulas What salt forms when aluminum combines with chlorine?
Aluminum has 3 valence electrons.
Loses 3 e- to reach octet.
Forms Al+3 ion.
Chlorine has 7 valence electrions.
Gains 1 e- to reach octet.
Forms Cl-1 ion.
If the compound is neutral, it will take 1 Al+3 ion for every 3 Cl-1 ions.
The formula is AlCl3.

17. Aluminum + Chlorine Cl Cl Al Cl

18. Ionic Bonds – Writing Formulas
CRISS-CROSS METHOD
Oxidation numbers (excluding charge) of each ion trade places to become the subscripts in the formula – must be reduced to lowest whole number ratio; 1’s are not written
Ca & S
Ca2S2
Al & Cl
AlCl3
CaS 18

19. Writing Ionic Formulas
Criss-Cross Method of writing ionic formulas:
Criss-cross charges to become subscripts
Drop the charges when crossing over.
Example: What salt is formed from sodium and sulfur?
Na forms +1 ions.
S forms -2 ions.
Na+1 + S-2  Na2S

20. Writing Ionic Formulas
sodium + chlorine 
calcium + bromine 
lithium + oxygen 
aluminum + oxygen 
magnesium + nitrogen 
Na+1 + Cl-1 
Ca+2 + Br -1 
Li+1 + O-2 
Al+3 + O-2 
Mg+2 + N-3 
NaCl
CaBr2
Li2O
Al2O3
Mg3N2

21. Writing Ionic Formulas
If the subscripts can be reduced, do so.
Example: calcium + oxygen
Ions: Ca+2 + O-2
Wrong: Ca2O2
Right: CaO
Example: lead + oxygen
Ions: Pb+4 + O-2
Wrong: Pb2O4
Right: PbO2

22. Ionic Bonds – Writing Formulas
Sodium and chlorine bond in a 1:1 ratio to form NaCl
Calcium and chlorine bond in a 1:2 ratio for form CaCl2
What determines each ratio & formula? ________________
oxidation numbers

23. Ionic Bonds – Writing Formulas
Try to predict the ratio and resulting formula for each of the following ions based on their oxidation numbers:
Ions
Oxidation Numbers
Ratio
Formula
Magnesium & Oxygen
Mg2+ & O2-
1:1
MgO
Lithium &
Sulfur
Aluminum & Oxygen
Sodium & Phosphorus
Barium &
Fluorine
Li+ & S2-
2:1
Li2S
Al3+ & O2-
2:3
Al2O3
Na+ & P3-
3:1
Na3P
Ba2+ & F-
1:2
BaF2

24. We will learn how to write nomenclature for:
Ternary Salts
3 or more elements
Includes a polyatomic ion
Salts with Multiple Oxidation Numbers
Can be binary or ternary
Includes a transition metal

25. Polyatomic Ions Polyatomic Ions – ions made of more than one atom.
Examples:
NO3-1
1 nitrogen atom and 3 oxygen atoms that collectively have a -1 charge.
SO4-2
1 sulfur atom and 4 oxygen atoms that collectively have a -2 charge.
PO4-3
1 phosphorus atom and 4 oxygen atoms that collectively have a -3 charge.
NH4+1
1 nitrogen atom and 4 hydrogen atoms that collectively have a +1 charge.

26. Polyatomic Ions in Salts
Treat them like single-atom ions.
But do not change their formula!
If you need more than one of a particular polyatomic ion, use parentheses.
Example:
Na+1 + NO3-1  NaNO3
Mg+2 + NO3-1  Mg(NO3)2
Al+3 + NO3-1  Al(NO3)3

27. Polyatomic Ions in Salts
K+1 + OH-1 
Ca+2 + OH-1 
Ga+3 + OH-1 
NH4+1 + Cl-1 
NH4+1 + S-2 
NH4+1 + P-3 
NH4+1 + SO4-2 
KOH
Ca(OH)2
Ga(OH)3
NH4Cl
(NH4)2S
(NH4)3P
(NH4)2SO4

28. Name
Formula
acetate
C2H3O2- or CH3COO-
ammonium
NH4+
carbonate
CO32-
chlorate
ClO3-
chlorite
ClO2-
chromate
CrO42-
cyanide
CN-
dichromate
Cr2O72-
hydrogen carbonate
HCO3-
hydroxide
OH-
hypochlorite
ClO-
nitrate
NO3-
nitrite
NO2-
perchlorate
ClO4-
permanganate
MnO4-
phosphate
PO43-
sulfate
SO42-
sulfite
SO32-
Polyatomic Ions
Some ions contain more than one element - called a polyatomic ion
The group as a whole has an overall charge
Examples:
Lithium and sulfate would bond together to make Li2SO4
Ammonium and sulfur would bond together to make (NH4)2S

29. Ternary Salt Naming
Contains 3 or more elements: cation & anion – most polyatomic ions are anions, only cation is ammonium (NH4+)
Naming:
Name the cation (no changes)
Name the anion (no changes)
Example: Na2SO4 = sodium sulfate
Exception: When ammonium is paired with an element anion
NH4Cl = ammonium chloride

30. Al & SO3 Al2(SO3)3 K & PO4 K3PO4 Ternary Salt Formulas + 3- 3+ 2-
You must use parentheses if you have more than one polyatomic ion. Be sure to criss-cross the oxidation numbers and write it OUTSIDE of the parentheses.
Al & SO3
Al2(SO3)3
K & PO4
K3PO4 30

31. Ternary Salt Formulas & Naming
Try to predict the formulas and names for each ternary salt:
Ions
Oxidation Numbers
Ratio
Formula
Name
Potassium & Hydroxide
K+ & OH-
1:1
KOH
potassium hydroxide
Calcium & Carbonate
Barium &
Nitrate
Sodium & Phosphate
Ammonium & Sulfur
Ca2+ & CO32-
1:1
CaCO3
calcium carbonate
Ba2+ & NO3-
2:1
Ba(NO3)2
barium nitrate
Na3PO4
Na+ & PO43-
1:3
sodium phosphate
NH4+ & S2-
1:2
(NH4)2S
ammonium sulfide

32. Salts with Multiple Oxidation #s Naming
Transition elements can form more than one type of positive ion.
For example, copper can form both Cu+ and Cu2+ ions, and iron can form both Fe2+ and Fe3+ ions.
Zinc and silver are two exceptions – they only have one oxidation number
The zinc ion is Zn2+ and the silver ion is Ag+.

33. Salts with Multiple Oxidation #s Naming
Transition elements can form more than one type of positive ion.
Naming:
Name the cation
Put the roman numeral representing the oxidation # of the metal in parentheses (do not indicate the charge)
Name the anion, changing the ending to “ide” (binary) or naming the polyatomic ion (ternary)
Example:
FeCl2 = iron (II) chloride
FeCl3 = iron (III) chloride

34. Salts with Multiple Oxidation Numbers Practice
Ions
Oxidation Numbers
Ratio
Formula
Name
Copper & Nitrate
Cu+ & NO3-
1:1
CuNO3
copper (I) nitrate
Lead &
Oxygen
Cobalt &
Hydroxide
Nickel & Phosphate
Chromium & Sulfur
Pb4+ & O2-
2:1
PbO2
lead (IV) oxide
Co3+ & OH-
3:1
Co(OH)3
cobalt (III) hydroxide
Ni2+ & PO43-
2:3
Ni3(PO4)2
nickel (II) phosphate
Cr2+ & S2-
1:1
CrS
chromium (II) sulfide