SCH 3UO atomic structure

SCH 3UO LESSON PLANS

Unit 1: Atomic Structure

Text : Chemistry 11 (Addison-Wesley)

Lesson One;
Review history of atom                                                             - finish questions on atomic history
- Handout: Atomic Structure to 1911 (use old Gr. 11 texts)     - finish questions on atomic history
- video: Part One-How We Found Out About Atoms              - bring $3.00 for packages
(18 min)

-see package notes on atomic structure

Lesson Two;
-Rutherford’s Atom                                                                     - handout: Modern Atom 1 #1-3
- review atomic number, mass number, protons,                       - Read p. 26-28
electrons, neutrons, ions                                                            - p.29 Practice #2, 4-7

Rutherford's Nuclear Atom
A) Structure
    -small, dense, positively charged nucleus containing protons (p⁺) and neutrons (n^o)
     each with a mass of 1 u (atomic mass unit)
    -shells of electrons (e^-) which surround thenucleus at a great distance (and occupy
     the largest part of the atom's volume); mass of 0.00054 u
    NOTE: 1 u = 1.66 x 10^-24 g
B) Definitions
    ATOMIC NUMBER
    -number of p⁺ in atoms nucleus
    -determines the "element"
    -all atoms of a particular element have the same atomic number
    -elements are "atoms having the same atomic number"
    MASS NUMBER
    -nmber of p⁺ and n^o in an atoms nucleus
    -determines the ISOTOPE
    -all atoms of a particular element DO NOT have the same mass number (#n^o is different)
    -isotopes are "atoms with same atomic number but different mass number"

Shorthand method: ^A_Z X where A =mass #, Z =atomic #, X = element symbol
# of neutrons = mass number - atomic number

Find protons, neutrons and electrons for various examples

Lesson Three;
Average Atomic Mass Part 1                                                    - complete lab questions
- review problem type #1(complete Modern Atom I #4a)        (due next class & every student hands in lab)
- Lab:   Pennium

ATOMIC MASS
-more correctly called the "average atomic mass" or in older cheistry texts, the atomic weight,
this is the mass of the average atom of an element in atomic mass units (u)
-this concept takes into account not only the mass of each individual isotope but also their
relative abundances in nature
-since the mass of the proton and the neutron are almost equal to 1.00 u, the atomic mass
is really an average number. Calculating the atomic mass for an element is, therefore,
calculating an average mass taking into account all of the existing isotopes and their
percentage abundance
    eg. the element consists of only two isotopes:
            B-10    19.78%     10.0129 u
            B-11    80.22%    11.0093 u
    Calculate the atomic mass based on the above data
-average atomic mass = (%abundance of isotope 1/100 X atomic mass of isotope 1)
                                        +(%abundance of isotope 2/100 X atomic mass of isotope 2)
                                        +(%abundance of isotope 3/100 X atomic mass of isotope 3)...
-average atomic mass B = (19.78/100 X 10.0129 u) + (80.22/100 X 11.0093u)
                                         = 1.9805516 u + 8.8319011 u
                                        = 10.81 u

Lesson Four;
- hand in Pennium Lab - isotope problem assignment (due on Day 6)
Average Atomic Mass Part 2 - Read p.29-31
- review problem type #2 (complete Modern Atom 1 #4bc)
- radioisotopes (reading assignment using old Gr. 11 texts)
- isotope problem assignment (#1-7 hand in & #8,9 bonus)

eg. Cu exists as only 2 isotopes: Cu-63 and Cu-65. If the atomic mass is 63.55, calculate the percentage
      abundance of each isotope.
            Let x be the % Cu-63
            Let (100 - x) be the % Cu-65
            The atomic mass = [63x + 65(100 - x)]/100 = 63.55
            cross multiply to get: 63x + 6500 - 65x = 63.55(100)
            rearrange equation to get: 6500 - 6355 = 65x - 63x
                                                        145 = 2x
                                                        72.5 = x
            The % abundance of Cu-63 is 72.5%, and % of Cu-65 = 100 - 72.5 = 27.5%

Lesson Five;
- handouts: types of reactions, players of the game, - Read p. 216-222
balancing nuclear reactions, types of radioactivity - p.222-223 Section 5.3 Questions #3-7
- complete p.219 #3-6 and p.220 #9,10 as a class

Lesson Six;
- hand in isotope problem assignment                                            - complete questions for lab on p.31-32
Lab: Half-life (p. 31-32 in text)                                                        analysis (a) to (e); graph paper in
- use Radioactivity & Half-life Activity kit for disks & shakers       package (due on Day 7 & every
(Room 200)                                                                                         student hands in lab)
Video: Nuclear Power (37 min)

Lesson Seven;
- hand in Half-Life lab - Read p.34-35
Nuclear Energy Part 2 - p.35 Practice #20-22
- handouts: How Does a Nuclear Plant Work, diagrams
(CANDU reactor, energy conversion conventional vs. nuclear)
Fission
-breaking apart of atomic nuclei into smaller nuclei accompanied by the release of energy.
*the source of energy in nuclear reactors!
eg. ²³⁵₉₂U + ¹₀n --> ¹⁴²₅₆Ba + ⁹¹₃₆Kr + 3¹₀n + 1.92 x 10¹⁰kJ

Fusion
-the formation of atomic nuclei by the joining together of the nuclei of lighter atoms
accompanied by the release of energy;
*source of energy in the sun!

Problems with Nuclear Reactors
    Loss of Coolant
-temperature increases to the point where the metal components (fuel rods) can melt or break
-water will turn to steam and steam can react with metals to produce H_2(g)
-pressure inside the reactor increases
-hydrogen and oxygen gas in air are explosive (breaching the building and releasing radioactive
gases into the air)
eg. Chernobyl, Three Mile Island
-in Chernobyl, not as much coolant was used, and carbon in the form of graphite made up the
control rods (carbon burns at high temperatures, resulting in a large fire)
-when heat is so great the core melts, a "meltdown" is said to occur
-radioactive waste can be buried, but dispersion in the atmosphere results in absorption into
water, plants and humans
    Can a Reactor Explode like a nuclear bomb?
-no! 90% U-235 is needed to explode a nuclear bomb (this is the critical mass), and must be
forced together under high pressure (not enough U-235 is in a reactor)
    Disposal of "Spent" Fuel
-what is done with plutonium-239? (produced after decay of U-238)
-Canada buries it in sealed containers underground in the Canadian Shield

Lesson Eight;
Modern Atom – II                                                                                - Read p.37-40
- handouts: Rutherford’s Model, Bohr Refinement, B/R Model,     - p.42 Practice #1-4
Why Energy Level                                                                                - p.45 Practice #6, 7
- Demo: Evidence of Energy Levels (Spectroscope)
- Explanation of Demo

Lesson Nine;
Quantum Mechanical Atom – Part 1                                                     - Read p.45-47
- handouts: The Quantum Mechanical Atom, Orbitals,                         - handout: Energy level diagrams
Multi-Electron Atoms                                                                            (Mg, Cl, Mn, As, Zr, Cd, Rb, Ru)
- as a class complete energy level diagrams for                                     - bring coloured pencils next class
B, Ne, Si, Ca, Mo (handout: Distribution of Electrons
in Atoms)

Lesson Ten;
Quantum Mechanical Atom – Part 2 - handout: The Quantum Mechanical Atom
- discuss where orbitals are on the periodic table (due on Day 12)
(outline s, p, d and f-blocks on blank periodic table)
- full electron configuration using periodic table
- short hand electron configuration
- energy level diagrams without template

Lesson Eleven;
Quantum Mechanical Atom – Part 3
- number of valence electrons
- electron configuration for ions
“expected vs. true” electron configuration (Cr, Ag)
Video: The Atom (World of Chemistry, 25 min)

note: experimental results show that completely full or half full orbitals are more stable
-jumps between s and d orbitals are allowed as they are close in Energy
-jumps between s and p orbitals do not occur as too much Energy difference

Lesson Twelve;
- hand in “Quantum Mechanical Atom” assignment
Start Trends Unit

Lesson Thirteen;
TEST

Return to Science home page