1. Atoms, Molecules & Ions Isotopes and % Abundance
....and the historical development of the human understanding of matter, atoms, and subatomic particles.

2. A compound made of carbon and oxygen was analyzed and the following data was obtained. Which law is illustrated by the data?
mass of C (g)
mass of O(g) 12 16
2.5
3.2
0.625
0.80 1
1.33
The law of conservation of matter
The law of multiple proportions
The law of constant composition
The law of conservation of mass 2

3. The law of conservation of matter The law of multiple proportions
A compound made of carbon and oxygen was analyzed and the following data was obtained. Which law is illustrated by the data?
mass of C (g)
mass of O(g) 12 16
2.5
3.2
0.625
0.80 1
1.33
The law of conservation of matter
The law of multiple proportions
The law of constant composition
aka law of definite proportions
The law of conservation of mass 3

4. The law of conservation of matter The law of multiple proportions
One compound of carbon and oxygen contains g of oxygen per gram of carbon, whereas a second compound contains g of oxygen per gram of carbon. What chemical law is illustrated by this data?
The law of conservation of matter
The law of multiple proportions
The law of constant composition
The law of conservation of mass

5. The law of conservation of matter The law of multiple proportions
One compound of carbon and oxygen contains g of oxygen per gram of carbon, whereas a second compound contains g of oxygen per gram of carbon. What chemical law is illustrated by this data?
The law of conservation of matter
The law of multiple proportions
This law can be demonstrated with molecular compounds and transition metal compounds because of the many oxidation state possibilities
CO and CO2
Fe2O3 and FeO
The law of constant composition
The law of conservation of grams

6. One carbon-oxygen compound contains 1
One carbon-oxygen compound contains g of oxygen per gram of carbon, whereas a second compound contains g of oxygen per gram of carbon. If the first compound has an equal number of oxygen and carbon atoms, what can we conclude about the composition of the second compound?
The second compound must have twice as many oxygen atoms per carbon atom.
The second compound must have half as many oxygen atoms per carbon atom.
The second compound contains half as many carbon atoms as the first compound.
The second compound contains double the carbon atoms of the first compound.

7. One compound of carbon and oxygen contains 1
One compound of carbon and oxygen contains g of oxygen per gram of carbon, whereas a second compound contains g of oxygen per gram of carbon. If the first compound has an equal number of oxygen and carbon atoms, what can we conclude about the composition of the second compound?
The second compound must have twice as many oxygen atoms per carbon atom.
The second compound must have half as many oxygen atoms per carbon atom.
The second compound contains half as many carbon atoms as the first compound.
The second compound contains double the carbon atoms of the second compound.

8. What happens to most of the α particles that strike the gold foil in Rutherford’s experiment, and why do they behave that way?
α particles are scattered across a range of deflection angles due to the high density of the foil nuclei.
Most α particles pass through the foil without being deflected because most of the volume of the foil atoms is empty space.
Most α particles are scattered at acute angles as they pass close to the foil nuclei.
Most α particles are deflected in a backwards direction from the foil due to the high density of the foil atom nuclei.

9. What happens to most of the α particles that strike the gold foil in Rutherford’s experiment, and why do they behave that way?
α particles are scattered across a range of deflection angles due to the high density of the foil nuclei.
Most α particles pass through the foil without being deflected because most of the volume of the foil atoms is empty space.
Most α are scattered at acute angles as they pass close to the foil nuclei.
Most α particles are deflected in a backwards direction from the foil due to the high density of the foil atom nuclei.

10. Radioactive substances emit “rays.” These rays are particles or energy. In the image below, which ray represents beta particles?
orange
red
green
any color could represent a beta particles, since we don’t know if the charge of the plates are the same magnitude.

11. Radioactive substances emit “rays.” These rays are particles or energy. In the image below, which ray represents beta particles?
orange
red
green
any color could represent a beta particles, since we don’t know if the charge of the plates are the same magnitude.
Let’s assume the plates are the same magnitude of charge, why do the alpha particles deflect less than the beta particles? 11

12. Radioactive substances emit “rays.” These rays are particles or energy. In the image below, which ray represents beta particles?
Let’s assume the plates are the same magnitude of charge, why do the alpha particles deflect less than the beta particles?
Beta particles have a 1− charge, and alpha particles have 2+ charge, thus one might think alpha might deflect more, however, the mass of alpha particle is ~8000 times more massive and thus does not bend as much. 12

13. Emissions from Radioactive Substances
Alpha particles, essentially a helium nucleus
made of 2 protons & 2 neutrons, +2 charge
represented as or
fairly heavy, slower moving
clothing is enough to stop their progress
Beta particles are essentially electrons
represented as or
very little mass, fast moving
requires a thin metal foil to stop their progress
Gamma rays is essentially energy
represented as
more energetic than x-rays
requires thick lead shield to stop their progress 13

14. How many nucleons (?) are there in a nuclide (aka isotope) of 14C?6 8 12 14

15. How many nucleons are there in a nuclide (aka isotope) of 14C (carbon-14)?6 8 12 14
Nucleons are protons and neutrons
Remember the mass number minus the atomic number ( = 8) always equals the number of neutrons. Mass number = number of nucleons. 14

16. How many electrons would an isotope of Cr3+ ion contain?21 24 28
not enough information to determine

17. How many electrons would an isotope of Cr3+ ion contain?21 24 28
not enough information to determine
24+
24e-
21e-
Cr3+ Cr
loses three
electrons

18. A particular atom of chromium has a mass of 52
A particular atom of chromium has a mass of amu, whereas the atomic weight of chromium is amu. Explain the difference in the two masses.
The amu value and the amu value represent two different isotopes of chromium.
The atomic weight of chromium is less than the mass of the specific chromium atom since atomic weights are used to describe neutral atoms.
The atomic weight of chromium (51.99 amu) is an average atomic mass of all the naturally occurring isotopes of chromium, whereas the is the mass of just one of those isotopes.

19. A particular atom of chromium has a mass of 52
A particular atom of chromium has a mass of amu, whereas the atomic weight of chromium is amu. Explain the difference in the two masses.
The amu value and the amu value represent two different isotopes of chromium.
The atomic weight of chromium is less than the mass of the specific chromium atom since atomic weights are used to describe neutral atoms.
The atomic weight of chromium (51.99 amu) is an average atomic mass of all the naturally occurring isotopes of chromium, whereas the is the mass of just one of those isotopes.

20. Which element is represented by the mass spectrum shown below?
beryllium
boron
carbon
neon
sodium

21. How many naturally occurring isotopes are there for boron?
Which element is represented by the mass spectrum shown below?
beryllium
boron
carbon
neon
sodium
How many naturally occurring isotopes are there for boron?

22. Naming Review

23. To determine the name of a molecule:
Is the compound ionic or molecular?
How can we determine this?

24. Ionic Compounds Name the cation (+ ion, always written first).
Name the anion (- ion, ends in –ide unless it’s a polyatomic ion: don’t change its ending).
Consider the use of a Roman numeral (used only with transition metals).
What/where are the transition metals?
What does the Roman numeral represent?
When writing a formula from the name, remember you have to balance the charges!

25. Molecular Compounds
Uses prefixes based on how many atoms of a given element are in the compound:
mono = 1 hexa = 6
di = 2 hepta = 7
tri = 3 octa = 8
tetra = 4 nona = 9
penta = 5 deca = 10
Ending of the second element is always –ide.
Do not use mono- with the first element if there’s only one.

26. Is the acid an oxyacid (contains an oxygen)?
Acids (1st element is H)
Is the acid an oxyacid (contains an oxygen)?
Oxyacids (contain a polyatomic ion)
If the PAI ends in –ate  -ic
If the PAI ends in –ite  -ous
Non-Oxyacids
Use the prefix hydro-
Use the suffix -ic

27. Go over naming practice homework: P.A1

28. For now, we are just learning how to determine the numbers themselves.
Oxidation Numbers
Will be used later on to keep track of electrons in Redox Reactions (oxidation- reduction reactions), when elements change oxidation numbers.
For now, we are just learning how to determine the numbers themselves.

29. Oxidation Oxidation Numbers aka Oxidation States
A concept devised to keep track of electrons in a redox reaction.
Increase in oxidation number = oxidation
LEO (Lose Electrons = Oxidation)
Decrease in oxidation number = reduction
says GER (Gain Electrons = Reduction)
The sum of oxidation numbers in neutral compounds must = 0
The sum of oxidation numbers in a polyatomic ion = the charge of the ion
Can also suggest OIL RIG; Oxidation is loss, Reduction is gain

30. Determining Oxidation #
The charge on a monatomic ion is the Ox #
Atoms in elemental form are zero
H in H2, atoms in a lump of iron, Fe, P atoms in P4
Nonmetals usually have negative Ox # - but they can be positive.
Oxygen is −2 in both ionic and molecular compounds except in peroxides in which the oxidation number is -1.
Hydrogen is always +1 when bonded to nonmetals and always −1 when bonded to metals.
Fluorine is −1 in all compounds. The other halogens are usually −1 in binary compounds, but when combined with oxygen they are positive and have various oxidation states.

31. The many oxidation states of manganese, Mn
Mn , Mn = 0
MnCl2 , Mn = +2
MnF3 , Mn = +3
MnO2 , Mn = +4
K3MnO4 , Mn = +5
K2MnO4 , Mn = +6
KMnO4 , Mn = +7
Methylcyclopentadienyl manganese tricarbonyl MnC5H4CH3(CO)3 , Mn = Say whaaat??

32. Determine the oxidation number of each element in the following substances
CaCl2
SO32-
PbO2
H2O
Cl2
H2O hydrogen peroxide S8
AlH3
SO42-
ClO3-

33. Determine the oxidation number of each element in the following substances+4 -2 +2 -1
CaCl2
SO32−
PbO2
H2O
Cl2
H2O hydrogen peroxide S8
AlH3
SO42−
ClO3− +4 +1 -2 -2 +1 -1 +3 -1 +6 -2 +5 -2

34. Determine the oxidation number of phosphorus in Mg2P2O7
Submit a numeric value. If it is negative, put on the - sign. If positive, just leave it.

35. Determine the oxidation number of phosphorus in Mg2P2O7+2 +5 -2
Mg2P2O7

36. Determine the oxidation number of iron in K4Fe(CN)6
Submit a numeric value. If it is negative, put on the - sign. If positive, just leave it.

37. Determine the oxidation number of iron in K4Fe(CN)6+1 +2 -1
K4Fe(CN)6
(CN= -1)

38. Determine the oxidation number of chromium in Na2Cr2O7

39. Determine the oxidation number of chromium in Na2Cr2O7+1 +6 -2
Na2Cr2O7

40. NO Li3N N2O N2 NO2 NO2− N2H4 NO3− NH3
Nitrogen is the master of multiple oxidation states. Determine the oxidation number of nitrogen in each of the following compounds. NO
Li3N
N2O N2
NO2
NO2−
N2H4
NO3−
NH3

41. NO Li3N N2O N2 NO2 NO2− N2H4 NO3− NH3
Nitrogen is the master of multiple oxidation states. Determine the oxidation number of nitrogen in each of the following compounds. +2 -2 +1 -3 NO
Li3N
N2O N2
NO2
NO2−
N2H4
NO3−
NH3 +1 -2 +4 -2 +3 -2 +5 -2 -2 +1 -3 +1