1. 1 - Intro to Chemical Bonding
“Bonding” is the process of joining atoms together
The Chemical Bond – Force holding atoms together within a substance
Intra-molecule bonds create stable water molecules

2. 1 - Intro to Chemical Bonding
How many water drops can sit on a coin?
Inter-molecule bonds make water molecules “sticky”

3. 1 - Intro to Chemical Bonding
Why does bonding occur?
Bonding creates a new arrangement of electrons, which is more stable than before.
Stable Octet – Arrangement of 8 valence electrons found in Noble gases
(2 valence electrons in He)
Everything changes in a direction of greater stability!

4. 1 - Intro to Chemical Bonding
Electrons are transferred between metallic losers and non-metal gainers in forming salt

5. Recall that there are two types of elements:
Metals (Losers)
Chemically weak
Low Ionization energy
1, 2, or 3 valence electrons
Lose electrons in reactions
Na 2-8-1
Aluminum
Foil

6. Recall that there are two types of elements:
Nonmetals (Gainers)
Chemically Strong
High Ionization energy
5, 6, 7 valence electrons
gain electrons in reactions
Cl 2-8-7
sulfur

7. Which leads to three types of “substances” formed
When a metal combines with a nonmetal
The Metal transfers e- to nonmetal forming ions
 these are called Ionic compounds
Salts
Like NaCl

8. Which leads to three types of “substances” formed
When a non-metal combines with a non-metal
Two Nonmetals share electrons with one another.
 These form Molecules and are called Molecular compounds (and elements)
Water
H2O

9. Which leads to three types of “substances” formed
When a metal atom is with other metal atoms
Metals – Pure or mixed (losers)
The lost electrons act to glue the metal ions together
These can form be pure metals
or Metallic alloys
Steel
Fe,Cr

10. Learning check How does one tell? Notice: in compounds
Identify each sample as ionic, molecular or metallic.
CO2
SrO
H2S Cu
Al NO3
C6H12O6
NaI
How does one tell?
Notice:
in compounds
the 2nd element is a gainer?
Is the first element a
loser or gainer?
Loser = ionic, gainer = molecular
Only loser = metallic ex: Cu

11. Learning Check Identify each sample as ionic, molecular or metallic.
CO2
SrO
H2S Cu
Al NO3
C6H12O6
NaI
Nonmetal bonded to nonmetal = molecular
Metal bonded to nonmetal = ionic
Nonmetal bonded to nonmetal = ?
All metal copper atoms = ?
metal bonded to nonmetals = ?
All nonmetals= ? ?

12. Section 2A Ionic Bonds Ionic Substances

13. Ionic Compounds -Made of Ions (Charged “atoms”)
Formed when metal atoms transfer electrons to nonmetal atoms
Ex: Na atom transfers 1 e — to Cl atom 2-8-7
Becomes Na+ ion and Cl- ion 2-8-8
Both with 8 valence electrons like noble gases: Stable “octet”
Video 4 min

14. Ionic bond: attraction between oppositely charged ions
Ex Na+ and Cl- in salt NaCl
Cation – Positively charged metal ion ex: Na 1+ “sodium” ion
Anion – Negatively charged nonmetal ion ex: Cl1- chloride” ion
Name: Sodium Chloride
sodium ions bonded to chloride ions

15. Na+ Cl- Na+ Cl- Cl- Na+ Cl- Na+
forms solid crystals with equal positive and negative charges so its neutral
Properties: Strong continuous chemical bonds = high melting points (above 3000C)
Where
Is the
Ionic
Bond?
FYI: Most of these compounds are “salts”

16. Ionic properties NaCl (aq)
Brittle: Like charged ions repel when struck
Good electrical conductors when dissolved in water
NaCl (aq)

17. Learning Check
In terms of loss or gain of electrons, how do metals and nonmetals behave differently during reactions?
Describe the three types of substances formed from metals and nonmetal elements.
Most compounds contain “atoms” with how many valence electrons? Explain.
In terms of electrons, how do ionic bonds and ionic compounds form?
In terms of forces (bonding), why do salts (ionic compounds) have such high melting points? Why are salts brittle?

18. 11. Which type of bond is formed when electrons
are transferred from one atom to another?
(1) covalent (3) hydrogen
(2) ionic (4) metallic
12. Which type of bond is found in sodium bromide?
(1) covalent (3) ionic
(2) hydrogen (4) metallic
35. Which of the following solids has the highest melting point?
(1) H2O(s) (3) SO2(s)
(2) Na2O(s) (4) CO2(s)

19. Ionic Substances Na+ Cl- Na+ Cl- Cl- Na+ Cl- Na+
“NaCl” is one Formula unit ( “molecule” ) smallest number of ions possible
Some are Binary compounds: made of two elements only
Ex: MgCl2,
magnesium chloride: Mg 2+ with 2 Cl-
NOTICE: Positives and negatives balance each other out so compound is neutral
Na+ Cl- Na+ Cl-
Cl- Na+ Cl- Na+
No separate
molecules

20. Learning Check: What kind of substance is NaCl? HDYK?
2. Why don’t we say “one molecule of NaCl”?
3. How many Na+ ions would be needed to “neutralize” an O-2 ion?
4. What do you think will be the chemical formula for sodium oxide?

21. 2B Lewis Structures for Ionic

22. Lewis (Electron Dot) Structures – used to show bonding
For Elements and Ions – dots or x’s used to represent valence electrons
Atoms
hydrogen: H Magnesium: Mg
e- configuration:
Oxygen: O Chlorine: Cl

23. Lewis structures for ions
Ex: Ions
Losers: hydrogen H Magnesium: Mg
Gainers:
Oxide: O Chloride: Cl 2+ 1+
[ ]2-
[ ]1- x x x

24. Learning Check:
1. Draw the Lewis electron dot symbols for the following atoms:
a. Nitrogen b. potassium c. sulfur d. aluminum
2. Draw the Lewis electron dot symbols for the following ions:
a. nitride ion b. potassium ion c. sulfide ion d. aluminum ion

26. Notice: Most gainer ions will end up with 8 dots;
Doesn’t matter what the element is.
Can you think of an exception?
Hydride- [H:]-1

27. Lewis structures in bonding
For Ionic bonding – Metal atoms pass electrons to nonmetal atoms to reach stable octet (8 val. e-)
Ex: NaCl: Na Cl x x
becomes Na+ [ Cl ]1-

28. Ionic Bonding
MgCl2 Mg + Cl Cl
becomes Mg 2+ [ Cl ]1-
[ Cl ]1-
x x x

29. [ ]2- Practice problems Mg O Mg2+ O x
Draw the Lewis e- dot structure for MgO
x x Mg O x
[ ]2-
Mg2+ O

30. Learning Check:
Draw the Lewis electron dot diagrams for the following ionic compounds: KF
K2S
CaF2

31. Section 3 Naming and Formula writing Ionic substances

32. Writing formulas and naming compounds
 All compounds are made of two parts
a “Loser” ……bonded to a …..“gainer”
Ionic compounds formulas = Empirical Formulas
– Show the lowest whole number ratio of Ions ex: NaCl
Ions combine in ratio to become neutral
Ex: MgCl2 : 1 Mg 2+ ion : 2 Cl – ions
Ex: NaCl
1 Na : 1 Cl

33. Writing formulas and naming compounds
Ex: MgCl2 : 1 Mg 2+ ion : 2 Cl – ions
Naming: named … Magnesium Chloride
(negative ions end in ide)
Notice: Loser ion (metal first), then gainer ion (nonmetal)
Ex: Sodium + oxygen Na1+  + O 2-
(need 2 to balance) Na1+ 
Sodium Oxide Na2O
The 2 is the
“Subscript”
Notice: No reference is made to how many
in the name (We don’t say “disodium oxide”)

34. Writing formulas: Where do you find the charge?
Look at the “oxidation state” (the typical charge)
Ex: Calcium Chloride
Ca+2
Cl-1
Cl-1
CaCl2

35. Name the following binary compounds: CaBr2 Na2O SrI2 Li3N
Practice problems:
Name the following binary compounds:
CaBr2
Na2O
SrI2
Li3N
Calcium Bromide
Sodium Oxide ?
Binary compounds: made of only two elements
Notice: no reference is made to how many.
What are the subscript numbers?
Ratios!

36. Potassium Oxide Magnesium Iodide Calcium sulfide Aluminum chloride
Practice
Write the empirical formula for the following compounds (remember to balance the charges!)
Potassium Oxide
Magnesium Iodide
Calcium sulfide
Aluminum chloride
Aluminum oxide
NEVER
leave charges on formulas! -2 +1
K2O +1 -2
K2O +2 -1
MgI2 -2 +2
Simplify
to lowest
ratio
Ca2S2 ? ? +3 -1 ? +3 -2 ?

37. Transitional metals – many with multiple charges
Use the “stock” system
Roman numerals which represent the charge of the positive ion
Transition elements can lose e- from outer and inner sublevels
Ex: Cu 1+  “copper one” ion
vs. Cu 2+  “copper two” ion
Copper(I) Oxide Cu O 2-
2 Cu O 2-
Cu2O
Which Copper oxide ?  Cu O
Cu = +2
Copper(II) oxide +2 -2

38. Fe can be +2 or +3 so need to distinguish
Ex: Fe2O3
Fe can be +2 or +3 so need to distinguish
Slice up into loser and gainer
Fe? 2 | O 3
Identify the charge on the gainer
Fe? 2 | O 2- 3
Iron(III) oxide +6
3(-2) = -6
2 = +3

39. Practice problems: name the following+1 -1
Copper (I) iodide
1. Cu I
2. Cu I2
3. Hg O
4. Hg2 I2 +2 -1
Copper (II) iodide ? +2 -2 ? +1 -1
Hg2+2 Mercury “one” ion -2
___ 2 +2
A “poly-atom-ic” ion

40. 19 Which formula correctly represents the composition of iron (III) oxide?
(1) FeO3 (3) Fe3O
(2) Fe2O3 (4) Fe3O2

41. Test your learning Name these: 1. Na2O 2. MgI2 3. PbI4 4. Hg2I2
Write formulas:
1. potassium oxide
2. Calcium nitride
3. Lead (II) iodide
4. Copper (I) sulfide
Draw Lewis structures for each #2 above

42. Polyatomic ions Ternary Compounds are large compound ions that stay together as one unit ex: ammonium NH4+ click on the slide

43. Polyatomic ions In Ternary Compounds (contain 3 or more elements) ex: NaOH
Sodium hydroxide

44. Polyatomic ions (charged “molecule”)
Most Names end in -ate or –ite means its bonded with oxygen.
Ex: SO4 2-  called “sulfate” ion
As in copper sulfate = CuSO4
SO3 2-  “sulfite” ion
NO3 1-  “Nitrate” ion
As in potassium nitrate = KNO3
NO2 1-  “Nitrite” ion
Notice: -ates have more oxygen and –ites have less.

45. Two ammonium ions bond for every one carbonate
Ex: sodium sulfate Na+  SO4 2-
2Na+  SO4 2-
Na2SO4
Ex: ammonium Carbonate NH CO3 2-
2 NH CO3 2-
(NH4)2 CO3
Notice: (NH4) Parentheses are used if more than one ion is represented – subscript comes after
Two ammonium ions bond for every one carbonate

46. Naming Problems 1. Na2CrO4 2. K2Cr2O7 3. (NH4)2S 4. NaOH 5. Ca(OH)2
(most compounds split after the first element)
1. Na2CrO4
2. K2Cr2O7
3. (NH4)2S
4. NaOH
5. Ca(OH)2
6. CaSO4
7. CaSO3

47. formula problems Write the formulas of these ternary compounds:
Magnesium sulfate
Aluminum nitrate
Copper (II) carbonate
Zinc acetate
Ammonium chloride -2 +2 -1 +3 ? ? ? -? ? ?

49. Test your learning
Name these: 1. NaC2H3O2 2. Fe(ClO3)2 3. K3PO4 4. SnO2 5. Na2O2
Write the formula: 1. Mercury(II) chlorite 2. Calcium carbonate 3. Ammonium sulfide 4. Lead (II) oxalate 5. Potassium permanganate

50. Ionic (salts)
Molecular
Metals