Atomic Structure
Name______
Hr _____
Notes Atoms:
Atomic Practice
Symbol / Name / # protons / # neutrons / # electrons / Atomic # / Mass #Section 4.1 Early Ideas About Matter
For each statement below, write true or false
_____ 1. Philosophers formulated explanations about the nature of matter based on their own experiences
_____ 2. Both Democritus and Dalton suggested that matter is made up of atoms
_____ 3. Dalton’s atomic theory stated that atoms separate, combine, or rearrange in chemical reactions
_____ 4. Dalton’s atomic theory stated that matter is mostly empty space
_____ 5. Dalton was correct in thinking that atoms could not be divided into smaller particles
Section 4.2 Defining the Atom
For each item in Column A, write the letter of the matching item in Column B
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Column A
_____ 1. Proposed the nuclear atom model
_____ 2. Determined the mass-to-charge ratio of an electron
_____ 3. Calculated the mass of an electron
Column B
a. Thomson
b. Millikan
c. Rutherford
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Draw and label a diagram of each atomic model
4. Plum pudding model
5. Nuclear atomic model
Complete the following table of proton, electron, and neutron characteristics.
Particle / Symbol / Location / Relative Charge / Relative MassProton
n
0
Lab 4-1: Black Box
This lab activity is an exercise in indirect measurement. The closed containers have partitions inside and a steel ball that can freely move. Although you will not be able to see or touch inside the container, you will have to determine the design of the inside by indirect means.
Problem: What is the configuration (design) of the inside of a closed container?
Procedure:
1. Move the steel ball around by carefully shaking and tilting the container. By the sound and Path of the steel ball, determine the shape and location of the partitions.
2. In the table below, indicate the number of the container and your hypothesis.
3. Retest your hypothesis and indicate any changes in the second drawing.
4. The teacher will reveal the actual configurations of the partitions at the end of the activity. Include these in your table.
Data:
Container # / Hypothesis / Retest / ActualQuestions:
1. List those things that you were able to determine and those you were not:
2. Is there any reason why you were successful for certain characteristics and not others?
Section 4.3 How Atoms Differ
Notes on isotopes:
Complete the following sentences:
1. The number of ______in an atom is referred to as its atomic number.
2. The periodic table is arranged by increasing ______.
3. Atomic number is equal to the number of ______in an atom.
4. The number of ______in an atom identifies it as an atom of a particular element.
5. The number of ______plus the number of protons is equal to the atomic mass of an element.
Use the figures below to answer the following questions:
6. What is the atomic number of osmium? ______
7. What is the chemical symbol for niobium? ______
8. What is the atomic mass of osmium? ______
9. What units is the atomic mass reported in? ______
10. How many protons and electrons does an osmium atom have? ______A niobium atom? ______
Label the mass number and the atomic number on the following isotope notation:
11. ______
12. ______
Write each isotope below in symbolic notation. Use the periodic table to determine the atomic number of each isotope.
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13. Neon-22
14. Helium-4
15. Cesium-133
16. Uranium-234
17. Cesium-132
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18. Which of the atoms in problems 13-17 are isotopes of the same element?
Complete the following tables:
Neutral Atoms:
Element / Atomic Number / Atomic Mass / Protons / Neutrons / ElectronsLead-207
Oxygen-16
Zinc-66
Astatine-210
Rutherfordium-261
Polonium-209
Nobelium-259
Isotopes:
Element / Atomic Number / Atomic Mass / Protons / Neutrons / ElectronsIron-56 / 56
26 / 58
Carbon-12 / 6 / 6
14 / 6
80 / 199
Mercury-201 / 201 / 80
List the three sets of isotopes:
Ions:
Atomic Number / Atomic Mass / Protons / Neutrons / Electrons8035Br-1
5626Fe+4
3919K+1
168O-2
2412Mg+2
Lab 4-2: Baseballium
Procedure:
1. The sample of the baseballium isotopes will be distributed to each laboratory group. The difference between the isotopes is very distinct. Each isotope has a different exterior color.
2. Count the total number of isotopes in your container and mass. Record on data sheet.
3. Sort the baseballium isotopes into groups according to color, each group representing a different isotope. Count the number of isotopes (spheres) in each group and record this number on the data sheet.
4. Weigh each sample of isotopes (spheres) and record the mass on the data sheet.
5. Return all isotopes to the sample container when you are finished weighing the sample and return the container to the instructor.
Data:
TYPE OF ISOTOPE / NUMBER OF ISOTOPE ATOMS IN THE SAMPLE / MASS OF ISOTOPE SAMPLE1. Clear Isotope
2. Red Isotope
3. Green Isotope
4. Blue Isotope
TOTAL
Questions:
1. Calculate the average mass of a baseballium atom. This average mass is the atomic mass of the element. (total mass of all the atoms /total number of atoms)
2. Calculate the atomic mass of 1 atom of each isotope. (total mass of colored isotope/number atoms of colored isotopes)
Clear ______Red ______Green ______Blue ______
3. Calculate the percent abundance of each isotope. (number of atoms of colored isotope/total number of atoms)
Clear ______Red ______Green ______Blue ______
4. Calculate the “contribution” of each isotope (Percent as a decimal (#3) x the mass of one atom of colored isotope(#2)).
Clear ______Red ______Green ______Blue ______
5. Calculate the total “weighted average mass” of all of the isotopes by adding all of the contributions. How does this value compare to your first average found by massing all of the isotopes and dividing by the total (#1)?
6. Find the average atomic mass of an atom that has two isotopes. One is 70.0 % with mass = 204 amu and the other is 30.0 % with mass = 205 amu. Show all work
Lab 4-3: Isotopic Pennies
Purpose: To learn a way in which scientists can determine the relative number of different isotopes present in a sample.
Procedure:
1. The teacher will give you a pre-1982 penny, a post-1982 penny, and a container filled with a mixture of 10 pre- and post-1982 pennies with the mass of the empty container. Record that information and the code number of your sealed container.
2. Determine the isotopic composition of the element “coinium.” That is, find the percent of pre-1982 pennies and post-1982 pennies in your container.
Data:
Mass (g)Code number of film canister
Mass of empty film canister
Mass of pre-1982 penny
Mass of post-1982 penny
Mass of sealed canister of pennies
Total mass of pennies
Calculations:
1. Number of pre-1982 pennies ______
2. Number of post-1982 pennies ______
3. Percent composition of “Coinium” Pre-1982 ______%
Post-1982 ______%
Questions:
1. Describe the procedure you used to find the percent composition of “coinium.”
2. What property of the element “coinium” is different in its pre- and post-1982 forms?
3. In what ways is the penny mixture within the film canister a good analogy or model for actual element isotopes?
Section 4.3 Weighted Atomic Mass
Determine the weighted atomic mass for the following:
Isotope / Mass (amu) / Percent Abundance20Ne / 19.992 / 90.48
21Ne / 20.994 / 0.27
22Ne / 21.991 / 9.25
Isotope / Mass (amu) / Percent Abundance
Zirconium-90 / 90 / 51.4
Zirconium-91 / 91 / 11.2
Zirconium-92 / 92 / 17.2
Zirconium-93 / 93 / 17.4
Zirconium-94 / 94 / 2.8
Determine the weighted atomic mass and identity of the element represented for the following:
Isotope / Mass (amu) / Percent Abundance63X / 62.930 / 69.17
65X / 64.928 / 30.83
Element: ______
Isotope / Mass (amu) / Percent Abundance35X / 34.969 / 75.77
37X / 36.966 / 24.23
Element: ______
Chapter 4 Test Review
Things to know:
1. Historical development of the atomic model
2. Parts of an atom, location, charge, relative mass
3. What atomic number and atomic mass represent
4. The definitions of isotope and ion and their notations
5. Be able to determine the number of protons, neutrons, and electrons given atomic number, atomic mass, and charge, and vise-versa
6. Calculate the weighted atomic mass
7. Distinguish the difference be direct and indirect evidence
Review questions:
1. List the contributions the following scientist made to the atomic model
- Democritus
- Dalton
- Aristotle
- Rutherford
- Thompson
2. What is the difference between direct and indirect evidence and how does it pertain to the development of the atomic model?
3. Create a table of protons neutrons, and electrons listing their charge, location, and relative mass.
4. Complete the following table:
Element / Isotopic notation / Atomic # / Mass # / Protons / Neutrons / Electrons / Charge(neutral if 0)
Aluminum / 27Al / 27 / 13 / 13
Bromine / 35 / 45 / -1
Uranium / 146 / neutral
4He / 2
Lithium / 7 / 3 / 2
Tungsten / 184 / 74
Xenon / 79 / 54
Magnesium / 12 / 12 / +2
14C / Neutral
5. Calculate the weighted atomic mass of the following isotopes
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Mass # / Exact weight / % abundance14 / 14.003074 / 99.63
15 / 15.000108 / 0.37
Element ______
Mass # / Exact weight / % abundance24 / 23.985042 / 78.99
25 / 24.985837 / 10.00
26 / 25.982593 / 11.01
Element ______
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