1. Please Do Now Get a Book and a Periodic Table
Put your name on your periodic table
Label GROUPS 1a,2a,3a,4a,5a,6a,7a,8
Label the alkali metals, the alkaline earth metals, the halogens, the noble gases, and the transition metals

2. Chapter 6

3. Molecules and Molecular Compounds
What does it mean to say that an atom is ‘neutral’?
What would happen to the charge of the atom is an electron was removed? Added?
What is a molecule?

4. Although there are only just over 100 elements, there are millions of different compounds!
Elements combine!
Only the noble gases tend to exist as isolated atoms (think noble = snobby)
Monatomic: consist of single atoms (mono = one)

5. Molecule: the smallest electrically neutral unit of a substance that still has the properties of the substance.
Made up of 2 or more atoms that act as a unit
Ex: Water, H2O
-What is in one molecule of water?
2 hydrogen atoms and 1 oxygen atom

6. Molecular compounds: compounds composed of molecules.
Generally 2 nonmetals
Most have low melting or boiling points so most exist in liquid or gas state at room temperature
Carbon Monoxide
Carbon Dioxide
Dihydrogen Monoxide
(see a pattern in naming? We’ll get to that later…)

7. Ions and Ionic Compounds
Ions: Atoms or groups of atoms with a positive or negative charge
This is where it’s important to know your valence electrons!
These are the outermost electrons of an atom
Use your periodic table to figure it out!
Group 1a has 1 valence electron
Group 8 has 8 valence electrons (ex is He=2)
Atoms want 8 valence electrons…so, will gain or lose!

8. Sodium, Na, Group 1a, 1 valence electron
Cation: ion with a positive charge (has lost an electron), generally groups 1a, 2a, 3a
Sodium, Na, Group 1a, 1 valence electron
Remember, atoms want to get to 8 valence electrons
Ask yourself: is it easier to lose 1 electron or gain 7?
Sodium will generally LOSE one electron= +1 charge
Na+1
What about Magnesium? Lithium?
What about Hydrogen?

9. For metallic elements, the name of the cation is the same as the name of the element
Sodium atom forms a sodium cation
Symbol = Na+1
Metals tend to have very different properties from their cations
Sodium metal is explosively reactive with water
Sodium cation is in table salt, stable in water

10. Anions
Anions: Atoms that have gained one or more electrons and have a NEGATIVE charge
Ex: Chlorine, group 7a, has 7 valence electrons
Ask yourself: is it easier to gain one electron or lose 7?
Gain 1= Cl-1
Chlorine Ion will gain one electron, -1 charge
The name of an ion usually ends in –ide
So a chlorine ion will be called chloride

11. Ionic Compounds
Ionic Compounds: Compounds made up of cations and anions
Usually composed of metal cations and nonmetal anions
Ionic compounds are electrically neutral
How Is this possible if they are made up of charged atoms???

12. Review Molecular compound Ionic Compound Unit: Molecule Formula Unit
Type of Elements: Nonmetals
Metals + Nonmetals
Physical States: Solid/liquids/gases
Solid
Melting Point: Usually Low
High
Example: Carbon dioxide
Sodium Chloride

13. Practice: Pg Pg

14. PDN 1. Get a book 2. Turn in your ‘Drawing Atoms’ project
3. On a separate sheet of paper:
Predict the charge of the ion formed by the following elements and write the complete symbol:
Chlorine
Sodium
Aluminum
Potassium
Xenon

15. Chapter 6 Section 2

16. Representing Chemical Compounds
Chemical formula: shows the kinds and numbers of atoms in the smallest representative unit of the substance
2 types: Molecular formulas and Formula Units
Molecular Formulas: shows the kinds and numbers of atoms present in a MOLECULE of a compound
Think 2 nonmetals!
Does not tell you anything about structure
Turn to pg 139

17. Formula Units: lowest whole number ratio of ions in an IONIC COMPOUND
Think: metal and nonmetal!
Not a molecule. 3 dimensional patterns of ions
Think Salt NaCl

18. The Laws of Definite and Multiple Proportions
The law of definite proportions: in samples of any chemical compound, the masses of the elements are always in the same proportion
NaCl: One sodium ion, one Chlorine ion. ALWAYS
Ratio will always be 1:1
Water? H2O: ratio will always be 2 H : 1 O

19. The Law of Multiple Proportions: whenever two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers
Think Water (H2o) and Hydrogen Peroxide(H2O2)
The ratio of oxygens will always be 1:2 because hydrogen peroxide has twice the number of oxygen atoms

20. Try It!
1. Carbon reacts with oxygen to form two compounds. Compound A contains 2.41 g of carbon for each 3.22 g of oxygen. Compound B contains 6.71 g of carbon for each 17.9 g of oxygen. What is the lowest whole-number mass ratio of carbon that combines with a given mass of oxygen?

21. How to solve? What do you want to know? Ratio of carbon to oxygen
How can you compare?
Find out how much carbon for each 1 g of oxygen for each compound (divide)
Compound A: g C / 3.22 g O= g C/ 1.00 g O
Compound B: 6.71 g C / 17.9 g O = g C / 1.00 g O
Compare the masses by dividing again!
Compound A carbon / compound B carbon
0.748 g C (compound A)/ g Carbon (compound) B
Equals 1.99= roughly 2! The ratio of carbon per grams of oxygen in the compounds is 2:1

22. More Practice!
1. Lead two compounds with oxygen. One compound contains 2.98 g of lead combined with g of oxygen. The other compound contains 9.89 g of lead combined g of oxygen. What is the lowest whole-number mass ratio of lead in the two compounds that combines with a given mass of oxygen?

23. Solve 1. What do you want to know? Lead to oxygen… solve for lead!
Divide for each compound to figure out how much lead/ 1 g of oxygen
Divide the lead values
This is your Ratio!

24. PDN Hand in your Definite Proportions/Multiple Proportions sheet
Get a Calculator
On a separate sheet of paper:
1. Calculate the % composition by mass for each element in:
NaCl
(NH4)3PO4
2. Carbon reacts with oxygen to form two compounds. Compound A contains 2.41 g of Carbon for each 3.22 g Oxygen. Compound B contains 6.71 g of Carbon for each 17.9 g of Oxygen. What is the lowest whole number mass ratio of carbon that combines with a given mass of oxygen? Show ALL work

25. Ionic Charges For monatomic ions, look at the periodic table
We know how to do this already!
For Transition metals, many have more than one charge! I have to give you the charge
Fe(II) ion (Read: “Iron two ion”)
Roman numeral gives you the charge
You can also use a suffix system
‘-ous’ cation with lower of two charges
‘-ic’ cation with higher of two charges
This system does not tell you the charge though!

26. Polyatomic Ions Poly-many
Polyatomic ions: tightly bound groups of atoms that behave as a unit and carry a charge.
The names of most of the polyatomic ions end in ‘–ite’ or ‘-ate’ : sulfite (SO3- and SO4-)
Charge for each ion is the same, different numbers of O
Look at the table on pg 147

27. Writing Ionic Formulas! (Yay!!!!)
Ionic = METAL AND NONMETAL!
Ionic bond = swap of electrons
Metals lose, nonmetals gain, COMPOUND IS NEUTRAL!!!!!
Binary Ionic Compound : (2 elements)
1. Write the symbols
2. Find the charges (periodic table)
3. Criss-Cross
4. Reduce if necessary

28. Ternary Ionic Compounds: Compound that contains atoms of three different elements
Polyatomic Ions!
How to write the formula:
Write the Symbols
Surround the Polyatomic Ion in parentheses (think: KEEP IT TOGETHER)
Write charges
Criss Cross (charge goes OUTSIDE parentheses

29. Naming Ionic Compounds
Binary:
1. Write the name of the metal (include roman numeral for transition metal)
2. Write the name of the nonmetal ending with –ide
Sodium Chloride, Iron (II) Oxide
Ternary:
Write the name of the cation (usually a metal, but ammonium (NH4) is a cation
Write the name of the anion (if polyatomic, just write the name on the chart, if nonmetal, end in –ide)

30. PDN 1. Turn in your Ionic Compounds Practice sheet
On a separate piece of paper:
2. Name the following compounds
CrF2
Ga(NO2)3
3. Write the formulas for the following compounds
Iron (II) bromide
Magnesium acetate

31. Molecular Formulas YAY!!!!
Molecular compounds involve electron SHARING
But… they can share in multiple ways!
Think of CO and CO2 = both would be named carbon oxide if we used ionic rules
Molecular compounds = TWO NONMETALS
How can you tell two molecular compounds apart? PREFIXES

32. Know Your Prefixes!!! Mono = 1 Di = 2 Tri = 3 Tetra = 4 Penta = 5
Hexa = 6
Hepta = 7
Octa = 8
Nona = 9
Deca = 10
You must know these prefixes for the test! I will not give them to you

33. So, to write the formula of a molecular compound, just decode the prefixes
Dihydrogen monoxide
Di = 2 hydrogen
Mono = 1 oxygen
Formula is H2O

34. Exceptions:
If there is only one atom of the first element, you don’t need the prefix ‘mono’ (still need it for the second element, though)
If the element starts with a vowel, drop the 2nd ‘o’ on ‘mono’
Monoxide, not monooxide

35. Naming Molecular Compounds
Use prefixes to indicate number of atoms
End second element in ‘-ide’
Example:
OF2 = oxygen difluoride (no ‘mono’ on first element)
Cl2O8 = dichlorine octaoxide

36. PDN Turn in your Molecular Compounds Practice sheet
On a separate piece of paper
Name the following compounds CO
CO2
Write the formula for the following compounds
Dihydrogen monoxide
Phosphorus trichloride

37. PDN Turn in your Drawing Ionic Compounds project
On a separate sheet of paper:
Name: NaCl, NH4Cl, and PbSO4
Write the formulas:
Magnesium Hydroxide
Iron (II) Sulfide
Ammonium Cyanide

38. Molecular Compounds Binary molecular compounds 2 NONMETALS
How can we tell the different compounds?
Prefixes!!!
To Name a Molecular compound:
Use prefixes to tell me how many of each atom
Name end in –ide
CO= carbon monoxide
CO2= carbon dioxide
You can leave the ‘mono’ off of the first element, but not the second

39. Prefixes Put these on the BACK of your periodic table Mono – 1 Di – 2
Tri – 3
Tetra – 4
Penta – 5
Hexa – 6
Hepta – 7
Octa – 8
Nona – 9
Deca - 10

40. Molecular formulas
Just use the prefixes to tell you how many of each atom!
Carbon tetrafluoride = CF4
Dihydrogen monoxide = H2O

41. The tricky part!!!
Ionic : metal and nonmetal, get charges and criss cross, NO prefixes
Molecular: two nonmetals, no charges, use PREFIXES

42. You try it! 1. Identify as ionic or molecular
Metal/nonmetal or nonmetal/nonmetal
Most on this practice are molecular (so use prefixes)