1. Chapter 3: Molecules, compounds, and chemical equations

2. Octet Rule
Octet Rule: the tendency for atoms to achieve 8 electrons in their valence shell
Natural electron configuration of the Noble Gases
Done by gaining, losing, or sharing electrons
Increases stability, less chance to react afterwords
H and He seek a “Duet”
Na = [Ne]3s1  Na+ = [Ne]
Cl = [Ne]3s23p5  Cl- = [Ne]3s23p6 = [Ar]

3. To gain or to lose electrons?
Goal is to achieve a noble gas electron configuration
Metals lose electrons
Nonmetals gain electrons
Its easier for a nonmetal (Ex: chlorine) to gain 1 electron vs losing 7 electrons.
Its easier for a metal (Ex: magnesium) to lose 2 electrons vs gaining 6 electrons.

4. Oxidation state
oxidation state/number – represents the number of electrons lost or gained by an atom of an element in that compound
It relates to the charge of the atom as well
If a sodium atom loses one electron it will have a positive charge and the oxidation state will be +1
If an oxygen atom gains two electrons it will have a negative charge and the oxidation state will be -2

6. Ionic Bonding
Ions: atoms that have a charge due to gain or loss of electrons
Anion: (-) charged atom – added electron(s)
Cation: (+) charged atom – lost electron(s)
Ionic Bond: a bond formed through the transfer of one or more electrons from one atom or group of atoms to another atom or group of atoms

7. Oxidation state
Formula Unit

8. Oxidation state
MgF2

9. Polyatomic Ion + Non-metal Polyatomic Ion + Polyatomic Ion
Ionic Compounds: compounds composed of oppositely charged ions that are held together by their attraction to each other
Metal + Non-metal
NaCl
Metal + Polyatomic Ion
NaNO3
Polyatomic Ion + Non-metal
NH4Cl
Polyatomic Ion + Polyatomic Ion
NH4NO3
Net charge on compound equal to zero

10. X X X X

11. Oxyanions SO42- Sulfate SO32- Sulfite PO43- Phosphate PO33- Phosphite
NO3-
Nitrate
NO2-
Nitrite
ClO4-
Perchlorate
ClO3-
Chlorate
ClO2-
Chlorite
ClO-
Hypochlorite

12. Covalent Compounds
Covalent Compounds: compounds composed of atoms bonded to each other through the sharing of electrons
Electrons NOT transferred
No + or – charges on atoms
Non-metal + Non-metal
Also called “molecules”
Examples:
CO2
Cl2
CH4

13. Covalent Bonding
or H-H
Duet or

14. Chemical formulas
Chemical formula – tells you the elements and relative atoms in a compound
2 types, molecular and empirical formula
Molecular formula give the actual number of atoms of each element in a compound
H2O2 = two H atoms and two O atoms
Empirical formula – gives the relative atom to atom ratio with whole numbers
H2O2 , greatest common factor is 2 so in empirical form H2O2 = HO
C6H12 = CH2

15. Structural formula
A structural formula uses lines to represent covalent bonds between atoms in a molecule
H2O2 structural formula below. The one on the right reflects bond angles and general shape
Double and triple bonds also represented

16. Molecular Models
Ball and stick molecular model – each colored ball represents a atom and the sticks represent the bonds between atoms
CH4
Space filling molecular model – size of each atom reflected in size of each sphere
Larger spheres have larger atomic radii
Model gives best 3-D image

17. Element and compound definitions
Atomic elements – elements that exist as single atomic units
Molecular elements – elements that exist as diatomic or polyatomic molecular units
Formula unit – basic unit of an ionic compound
Polyatomic ions – an ion composed of two or more atoms
PO43-

18. Nomenclature (naming compounds)
Ionic compounds
Molecular compounds
Acids

19. Rules For Naming Ionic Compounds
Name the cation by its elemental/polyatomic name Na+Cl- = NaCl = sodium chloride
If the metal is a transition metal with a variable charge, use a Roman Numeral in parentheses for its charge FeCl2 = iron(II)chloride
Next, name the anion and change its ending to “-ide” Cl- = chloride
If the anion is polyatomic, do not change the ending to “-ide” NaNO3 = sodium nitrate
Do NOT use prefixes (mono, di, tri etc.) to indicate how many of each atom are present

20. Iron (II) Chloride
FeCl2
Iron (III) Chloride
FeCl3

21. Hydrated Ionic compounds
Hydrates – contain a specific number of water molecules associated with each formula unit
The waters can typically be removed with heating
Ionic compound naming is the same, just add in hydrate and the prefix for the amount of waters

22. Problems Write the name for the following compounds: KI MgBr2 Al2O3
FeCl2
CaSO4
Ba(NO2)2
Cu(NO3)2
potassium iodide
magnesium bromide
aluminum oxide
iron(II)chloride
calcium sulfate
barium nitrite
copper(II) nitrate

23. Write the Formula for the following ionic compounds: Sodium Fluoride
Calcium Sulfite
Calcium Chloride
Iron (III) Oxide
Cobalt (II) Hydroxide
Ammonium Bromide
Ammonium Carbonate
Aluminum Carbonate
NaF
CaSO3
CaCl2
Fe2O3
Co(OH)2
NH4Br
(NH4)2CO3
Al2(CO3)3

24. Naming Covalent Compounds
Name the first non-metal by its elemental name
Add a prefix to indicate how many
If only one atom, don’t put mono 1
mono 6
hexa 2 di 7
hepta 3
tri 8
octa 4
tetra 9
nona 5
penta 10
deca
4) Name the 2nd non-metal and change its ending to “-ide”
5) Add a prefix to indicate how many

25. Problems Write the name of the following compounds: CO NI3 N2O SF6
B2O3
carbon monoxide
nitrogen triiodide
dinitrogen monoxide
sulfur hexaflouride
diboron trioxide

26. Write the formula for the following compounds:
Phosphorous Pentachloride
Nitrogen Monoxide
Dinitrogen Tetroxide
Tetraphosphorous Decoxide
PCl5 NO
N2O4
P4O10

27. Naming Acids Acids that do not contain oxygen HCl = hydrochloric acid
Begin the name with “hydro”
Name the anion, but change the ending to “-ic”
Add “acid” on the end
HCl = hydrochloric acid
HF = hydrofluoric acid
EXCEPTION, if in the gas phase, treat like a regular covalent compound for naming with no prefixes
HCl(g) = hydrogen chloride

28. Acids that contain oxygen/oxyanions
Do not put “hydro” at the beginning
Begin the name with the anion
If the anion has the ending “-ate,” change this to “-ic acid”
If the anion has the ending “-ite,” change this to “-ous acid”
HClO4 perchloric acid
HClO3 chloric acid
HClO2 chlorous acid
HClO hypochlorous acid

29. Problems Name the following HBr(g) HBr(aq) HNO2(aq) HNO3(aq) HI (aq)
HI (g)
H2CO3 (aq)
H3PO4 (aq)
H3PO3 (aq)
HCN (aq)
Hydrogen bromide
Hydrobromic acid
Nitrous acid
Nitric acid
Hydroiodic acid
Hydrogen iodide
Carbonic acid
Phosphoric acid
Phosphorous acid
hydrocyanic acid

30. The Mole

31. 1 pair of kings = 2 kings
1 dozen eggs = 12 eggs
2 pairs of kings = 2 x 2 kings = 4 kings
2 dozen eggs = 24 eggs

32. The Mole Abbreviation: “mol” 1 mole = 6.022 x 1023 things
Avogadro’s number
Abbreviation: “mol”
1 mol = The number of carbon atoms in 12g of C-12
How much does this mole of carbon weigh?

33. Mole as a conversion factor
1 mole = X1023 things
1 mole C = x 1023 C atoms
1mol H2O = x1023 H2O molecules
If you have moles of something, you can convert to atoms or molecules of that something

34. Molar mass The mass, in grams, of one mole of any element or compound
Abbreviated with capital, italicized M
Unit = grams/mole = g/mol
Gives us a way to go from grams to moles

35. Formula mass Also known as molecular weight
The mass, in amu, of one molecule of a compound
Very closely related to Molar mass
Use periodic table for atomic weight of each element
CO2
Made of 1 carbon atom and 2 oxygen atoms
Atomic mass of each carbon is amu
Atomic mass of each oxygen is amu

36. Molar Masses for elements and molecules
Use periodic table to figure out Molar mass for each element.
Carbon
1 atom of carbon is amu
1mole of carbon is grams
Molar Mass = g/mol
H2O
Made of 2 hydrogen atoms and 1 oxygen atom
Molar mass of each hydrogen is g/mol
Molar mass of each oxygen is g/mol

37. Problems
You need mol Cu for an experiment, how many grams is this? How many atoms of Cu is this?
You have g Hg. How many moles are present?
Write the molecular formula or formula unit for the compounds above.
What are the molecular weights for the compounds above?

38. Composition of compounds
Mass percent – the percentage of an element in a compound. (amu, g, g/mol interchangeable since it is a ratio)
Mass percent of H in H2O
1.008 amu per H atom x 2 H atoms = amu
amu for H2O

39. If you have 55.4 grams of H2O, how many grams of that is hydrogen?
11.19% of H2O is hydrogen = in decimal form
55.4 gH2O x = gH
A way to go from grams of molecule to grams of an element of that molecule

40. Mole ratios of a molecule
The atoms of an element in a molecule can be represented as a mole ratio
2 atoms of H in 1 molecule of H2O
2 mol of H in 1 mol of H2O
2:1 H:O ratio
3 mol of Cl in 1 mol FeCl3
3:1 Cl:Fe ratio
Mole ratio gets you from moles of 1 thing to moles of another

41. Grams of molecule Moles of molecule Moles of element Grams of element
55.40 grams H2O
Use Molar Mass
Moles of molecule
3.075 mol H2O
Use Mole ratio
Moles of element
6.150 mol H
Use Molar Mass
Grams of element
6.199 grams H

42. Chemical equations H2 (g) + Cl2(g)  2 HCl (g) Reactants Product(s)
Coefficient
Physical State
Subscript
H2 (g) + Cl2(g)  2 HCl (g)
Reactants
Product(s)

43. Law of conservation of Mass
Matter is neither created, nor destroyed, but is merely rearranged
The mass of the reactants must equal the mass of the products
Atoms in the reactants must equal atoms in the products
H2 (g) + Cl2(g)  2 HCl (g)

44. Balancing Chemical Equations
Zn(s) + HCl(aq)  H2(g) + ZnCl2(aq)
Write the unbalanced equation
Balance the atoms of one element (saving single elements for last)
Choose another element and balance it
Continue until all elements have the same number of atoms on both sides of the equation
Check yourself

45. Problems __ N2(g) + __ H2(g)  __ NH3(g)
__ Fe(s) + __ Cl2(g)  __ FeCl3(s)
__NH3(g) + __O2(g)  __NO(g) + __H2O(g)
__C5H12(l) + __O2(g)  __CO2(g) + __H2O(g)

46. Organic molecules
Living organisms are comprised primarily of organic molecules
Composed of carbon mainly, but also hydrogen, nitrogen, oxygen, and sulfur
Methane, CH4, is the simplest organic molecule
Isooctane C8H18
Ethanol C2H6O

47. Hydrocarbons and functional groups
Hydrocarbons – major class of organic molecules containing carbon and hydrogen
Octane C8H18
Benzene C6H6
Functional group – a characteristic atom or group of atoms
Commonly found attached to hydrocarbons
Organic chemistry focuses on chemistry with organic molecules
Reactions transform one functional group into another, changing the connectivity of the atoms to produce new products
Alcohol group

48. Functional groups

50. Chapter 3…all done