Download CHEMISTRY – UNITS 3 and 4 REVIEW PACKET Name Date

CHEMISTRY – UNITS 3 and 4 REVIEW PACKET
Name _______________________________________________________
Date ________________________________
ATOMIC STRUCTURE
Draw a picture of each model of an atom. Write the main/key point of each atom.
Name of model
Rutherford’s
Gold Foil (hard
sphere model)
Picture of model
Key point of the model
Bohr model –
Electron shell
diagrams
Wavemechanical
model
Label the following parts of the picture: proton, neutron, electron, nucleus, orbital,
valence electron.
What is the total mass of the nucleus of the atom? ____________________________________
What is the total mass of the atom (including electrons)? ____________________________
Complete the table
Subatomic Particle
Mass
Charge
Location in atom
Use the two pictures to answer the questions.
1) How many protons does each atom have? Atom 1: ___________ Atom 2: _____________
2) What kind of element is each atom? Atom 1: _______________ Atom 2: _______________
3) How many neutrons does each atom have? Atom 1: ___________ Atom 2: ____________
4) What is the word that describes two atoms that have the same # of protons but
different numbers of neutrons? _____________________________
5) Are these pictures an example of isotopes? ____________________________
VALENCE ELECTRONS / ELECTRON SHELL DIAGRAMS / LEWIS DOT DIAGRAMS
What is a valence electron? ______________________________________________________________
How can you figure out the number of valence electrons in an atom (using the
Periodic Table?) __________________________________________________________________________
What is an electron configuration? _________________________________________________________
Write the electron configuration for each element. Write the number of valence
electrons for that element.
C: _________________________________________; Valence electrons: ______________________________
Al: ________________________________________; Valence electrons: ______________________________
Li: _________________________________________; Valence electrons: _____________________________
Fe: _________________________________________; Valence electrons: ____________________________
*Atoms that are chemically similar have the same number of __________________________.
Lewis electron dot diagram: shows the _______________________________ ONLY around the
element symbol. Draw the Lewis dot diagrams for C, Al, Li, and Fe below.
CALCULATING AVERAGE ATOMIC MASS
Formula:
Use the information given to calculate the average atomic mass.
1. 80% 127I, 17% 126I, 3% 128I
2. 15% Fe-55, 85% Fe-56
3. 95%14N, 3%15N, 2%16N
4. Element X has two isotopes. If 72.0% of the element has an isotopic mass of 84.9
amu and 28.0% has an isotopic mass of 87.0 amu, the average atomic mass of
element X is numerically equal to
(1) (2.0 + 98.9)(28.0 + 87.0)
(2) (72.0-84.9)(28.0-87.0)
(3) (0.720)(84.9)+(0.280)(87.0)
(4) (72.0)(84.9)+(28.0)(87.0)
5. The average isotopic mass of chlorine is 35.5 amu. Which mixture of isotopes
(shown as percents) produces this mass?
(1) 50% C-12 and 50% C-13)
(2) 50% Cl-35 and 50% Cl-37)
(3) 75% Cl-35 and 25% Cl-37)
(4) 75% C-12 and 25% C-13)
6. Carbon exists as three isotopes: C-12, C-13, and C-14. Carbon has an average
atomic mass of 12.0107 amu. This indicates that
(1) any sample of carbon consists of an equal amount of each type of isotopes.
(2) any sample of carbon consists of mostly the C-13 isotope.
(3) any sample of carbon consists of mostly the C-12 isotope.
(4) all carbon atoms have a mass of 12.0107 amu.
(5) all carbon atoms have a mass of 12.0107 amu.
On the picture below, label the orbital with the highest energy and the orbital with
the lowest energy.
Highest energy: ______________________
Lowest energy: ______________________
1. If an electron gets “excited” , does it move to a higher or lower energy level?
______________________________________
2. Is that electron absorbing or emitting energy? ________________________________________
3. When an excited electron falls back to a lower energy, is it absorbing or emitting
energy? _______________________________
NUCLEAR CHEMISTRY – TRANSMUTATION

WHAT IS THE MOST IMPORTANT TOOL TO USE WHEN SOLVING NUCLEAR
CHEMISTRY PROBLEMS??? _________________________________________________________
What are the 2 types of transmutation reactions?
1.) _____________________________________________________
2.) _____________________________________________________
 How can you tell the difference between the two? ____________________________________
 Why does natural transmutation occur?
 What determines if a nucleus is stable?
Using Tables N and O, write the nuclear decay equations for:
14C

53Fe

238U

Use the graph below to answer the question.
Explain why C-12 is a stable nuclide.
a) Based on this graph, what particle is emitted during the nuclear decay of a Po-218
atom?
b) Explain why the U-238 disintegration series ends with the nuclide Pb-206.
Complete the following artificial transmutation reactions:
27Al
42K
+ 42He  10n + X
+ 0-1e  00 + 210n + X
NUCLEAR CHEMISTRY – FISSION, FUSION, PRACTICAL APPLICATION
Fission: Takes ____ ________________ nucleus and splits into ________ _______________ nuclei.
Fusion: Takes ____ ________________ nuclei and joins to form _______ ______________ nucleus.
Circle the correct answer: A fission or fusion reaction is started by bombarding
(hitting) a nucleus or nuclei with (a high energy particle / a slow moving neutron).
Do these reactions produce a little energy or high energy? ________________________
What is the energy form that they produce? ________________________________________
Draw a picture of a fission reaction:
Draw a picture of a fusion reaction:
Practical Uses of Radioisotopes (Why do we care??)
Carbon-14
Iodine-131
Techmetium-99
Cobalt-60
Carbon-14
Uranium-238
CALCULATING NUCLEAR DECAY / HALF-LIFE
Fraction remaining: what’s leftover compared to what we started with.
Formula: __________________________________
What is n? ___________________________________________________________________________________
How can you figure out n?
Fraction remaining = ________________________
½ = 1/2n  n =
¼ = 1/2n  n =
1/8 = 1/2n  n =
1/16 = 1/2n  n =
1/32 = 1/2n  n =
Formula for calculating half-life and/or total time elapsed:
Solve each problem based on the information given in the problem.
If a scientist purifies 1.0 gram of radium-226, how many years must pass before
only 0.50 gram of the original radium-226 sample remain unchanged?
Which fraction of an original 20.00-gram sample of nitrogen-16 remains unchanged
after 36.0 seconds?
(1) 1/5
(2) 1/8
(3) 1/16
(4) 1/32
PRACTICE PROBLEMS!
1. Which equation represents a
transmutation reaction?
7.
2. Which is an electron configuration for an
atom of phosphorous in the excited state?
(1)
(2)
(3)
(4)
2-8-5
2-8-8
2-8-4-1
2-8-7-1
3. What is the total number of valence
electrons in an atom of oxygen in the ground
state?
(1)
(2)
(3)
(4)
8. Given the nuclear equation:
2
4
6
7
4. The amount of energy released from a
fission reaction is much greater than the
energy released from a chemical
reaction because in a fission reaction
(1) mass is converted into energy
(2) energy is converted into mass
(3) ionic bonds are broken
(4) covalent bonds are broken
5. How many days are required for 200.
grams of radon-222 to decay to 50.0
grams?
(1) 1.91 days
(2) 3.82 days
(3) 7.64 days
(4) 11.5 days
6. Which nuclear emission has the weakest
penetrating power?
(1) alpha particle
(2) beta particle
(3) gamma radiation
(4) positron
9. Which type of reaction converts one
element to another element?
(1)
(2)
(3)
(4)
neutralization
polymerization
substitution
transmutation
10. Which equation is an example of
artificial transmutation?
11. Two atoms will always have the
same atomic number if they have the
same
1. mass number
2. number of protons
3. number of neutrons
4. number of nucleons
12. Which particles account for most of
the mass of the atom?
1. protons and neutrons
2. protons and electrons
3. neutrons and electrons
4. neutrons and positrons