student student mr. dolgos regents chemistry

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Mr. Dolgos Regents Chemistry

PRACTICE PACKET Unit 2: Atomic Theory

*STUDENT* *STUDENT*

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Name ____________________________ Period _______ History of Atomic Theory Fill in the missing information in the chart below: Name of Researcher Equipment Sketch of Model Major Idea/Discovery

N/A

All atoms of a given element are identical in mass and properties

Thomson

Rutherford

N/A

Electrons travel around the nucleus in well-defined paths called orbits (like planets in a solar system)

N/A

Electrons have distinct amounts of energy and move in areas called orbitals Developed after the famous discovery that energy can behave as bothwaves & particles

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Notice there are two different atoms of zirconium (Zr) listed. These different versions are called ISOTOPES. What one subatomic particle is different from one isotope to the other? __________________________________

Atomic Structure Worksheet **Assume all are neutral atoms! Fill in the blanks in the following worksheet. Please keep in mind that the isotope represented by each space may NOT be the most common isotope or the one closest in atomic mass to the value on the periodic table.

Atomic symbol

Atomic number

Protons Neutrons Electrons Mass number

C 8

12 24

31 40

40 89

30 35

42 98

W 183

105 71

95 243

Cr 27

83 209

90 142

Md 259

Se 80

40 51

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Atomic Theory- Neutral Atoms and their subatomic parts **IMPORTANT**If the mass number is not given to you, round the atomic mass that you find on the Periodic Table for that element. How many protons, neutrons, and electrons are present in the following neutral atoms?

vanadium potassium nitrogen platinum argon helium

What is the name of the element that has neutral atoms that contain:

5 protons? 16 electrons?

_____________________ _____________________


_____________________ _____________________

25 protons? 1 electron?

_____________________ _____________________


_____________________ _____________________


_____________________ _____________________

P =

N =

e =

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Complete the following chart: (assume the overall charge on all atoms = 0….except the last one!)

Element Symbol Atomic Number

# of Protons

# of Neutrons

Mass Number (amu)

# of Electrons

Hydrogen

1

He 4

Na 12

Potassium

39

20 20

26 30

Rb 86

Carbon

6

Xenon

131

16 15

At 126

14 7

Copper

64

Ne 10

23 27

Lithium Ion

Li+ 3

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P, n, e of ions **IMPORTANT**If the mass number is not given to you, round the atomic mass that you find on the Periodic Table for that element. Write the full chemical symbol for the ion with:

1) 12 protons and 10 electrons:




Determine the number of p, n, e for the following ions: Cu2+ Li+ O2- p = n = e =

Cl- Al3+ I7+

# protons # electrons # neutrons Atomic # Mass #

Lithium1+ 3 4

Phosphorus3- 18 31

Vanadium0 23 51

Krypton0 48 36

Barium4+ 56 137

Uranium5- 97 146

P =

N =

e =

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For the following atoms/ions determine the number of protons, neutrons, electrons, mass number, and nuclear charge. ATOM

or ION? PROTONS NEUTRONS ELECTRONS MASS

NUMBER NUCLEAR CHARGE

15N

Cu+2

8B+3

17O

F-1

206Pb

208Pb

Ag+1

Zn+2

Mg

S-2

Question: Which of the above atoms are isotopes of one another? Explain how you know this. ___________________________________________ _________________________________________________________

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ATOM

or ION? PROTONS NEUTRONS ELECTRONS MASS

NUMBER NUCLEAR CHARGE

Al+3

37Cl

23Na+1

He

15O-2

14C

C

Au+3

U

222Rn

Cu+1

Cu+2

Question: Which of the above atoms are isotopes of one another? Explain how you know this. ___________________________________________ _________________________________________________________

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Calculate the atomic mass of each of the following isotopes. SHOW ALL WORK. Element Mass Percent Abundance 1) copper-63 62.9396 amu 69.17% copper-65 64.9278 amu 30.83% 2) uranium-235 235.0439 amu 0.72% uranium-238 238.0510 amu 99.28% 3) hydrogen-1 1.0078 amu 99.985% hydrogen-2 2.0140 amu 0.015% 4) element Q-8 8.0 amu 10.0% element Q-9 9.0 amu 20.0% element Q-10 10.0 amu 70.0%

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Weighted Averages HW (SHOW ALL WORK!) Name _____________________ *You can round the masses given to you or use them as given – just be consistent!

1) Element X exists in three isotopic forms. The isotopic mixture consists of 10.0% 10X, 20.0% 11X, and 70.0% 12X. What is the average atomic mass of this element?

2) Element Y exists in three isotopic forms. The Isotopic mixture consists of 15.0% 21X, 65.0% 22X, and 20.0% 23X. That is the average atomic mass of this element?

3) A mystery element occurs in nature as two isotopes. Isotope A has a mass of 10.0130 amu and its abundance is 19.9%; Isotope B has a mass of 11.0093 amu and its abundance is 80.1%. From this data, calculate the atomic mass of the element and show all work. Lastly, identify the element.

4) A mystery element occurs in nature as two isotopes. Isotope A has a mass of

62.939598 amu and its abundance is 69.17%; Isotope B has a mass of 64.927793 amu and its abundance is 30.83%. From this data, calculate the atomic mass of the element and show all work. Lastly, identify the element.

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5) A mystery element occurs in nature as three isotopes. Isotope A has a mass of 15.994915 amu and its abundance is 99.762%; Isotope B has a mass of 16.999132 amu and its abundance is 0.0380%; Isotope C has a mass of 17.999160 amu and its abundance is 0.2000%. From this data, calculate the atomic mass of the element and show all work. Lastly, identify the element.

Isotopes and Average Atomic Mass Example: A sample of cesium is 75% 133Cs, 20% 132Cs, and 5% 134Cs. What is the average atomic mass? Determine the average atomic mass of the following mixtures of isotopes. 1. 80% 127I, 17% 126I, 3% 128I 2. 50% 197Au, 50% 198Au

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3. 15% 55Fe, 85% 56Fe 4. 99% 1H, 0.8% 2H, 0.2% 3H 5. 95% 14N, 3% 15N, 2% 16N 6. 98% 12C, 2% 14C

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Regents Chemistry Name _________________________

Principal Energy Level Worksheet

Element e-configuration

Carbon

1s __

2s __ 2p __ __ __

Helium

1s __

Neon

1s __

2s __ 2p __ __ __

Oxygen

1s __

2s __ 2p __ __ __

Sulfur

1s __

2s __ 2p __ __ __

3s __ 3p __ __ __ 3d __ __ __ __ __

Aluminum

1s __

2s __ 2p __ __ __

3s __ 3p __ __ __ 3d __ __ __ __ __

Sodium

1s __

2s __ 2p __ __ __

3s __ 3p __ __ __ 3d __ __ __ __ __

Lithium

1s __

2s __ 2p __ __ __

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Calcium

1s __

2s __ 2p __ __ __

3s __ 3p __ __ __ 3d __ __ __ __ __

4s __ 4p __ __ __ 4d __ __ __ __ __ 4f __ __ __ __ __ __ __

Fluorine

1s __

2s __ 2p __ __ __

Chlorine

1s __

2s __ 2p __ __ __

3s __ 3p __ __ __ 3d __ __ __ __ __

Hydrogen

1s __

Magnesium

1s __

2s __ 2p __ __ __

3s __ 3p __ __ __ 3d __ __ __ __ __

Tin

1s __

2s __ 2p __ __ __

3s __ 3p __ __ __ 3d __ __ __ __ __

4s __ 4p __ __ __ 4d __ __ __ __ __ 4f __ __ __ __ __ __ __

5s __ 5p __ __ __ 5d __ __ __ __ __ 5f __ __ __ __ __ __ __

Potassium

1s __

2s __ 2p __ __ __

3s __ 3p __ __ __ 3d __ __ __ __ __

4s __ 4p __ __ __ 4d __ __ __ __ __ 4f __ __ __ __ __ __ __

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Construct Bohr diagrams for the following:

Na electron configuration ___________

F electron configuration ___________

O electron configuration ___________

Li+ electron configuration ___________

Cl- electron configuration ___________

Ne electron configuration ___________

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Draw Lewis Dot Diagrams for the following:

Charge ____ # Valence e- ____

N # unpaired valence e- ____ # of bonds _____


C # unpaired valence e- ____ # of bonds _____


Li+ # unpaired valence e- ____ # of bonds _____


He # unpaired valence e- ____ # of bonds _____


O # unpaired valence e- ____ # of bonds _____


B # unpaired valence e- ____ # of bonds _____


S # unpaired valence e- ____ # of bonds _____


Kr # unpaired valence e- ____ # of bonds _____


Se2- # unpaired valence e- ____ # of bonds _____


Ca+2 # unpaired valence e- ____ # of bonds _____

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Bohr and Lewis Dot Diagrams

Element Electron Configuration

# Valence e-

# Kernel e- Bohr Diagram Lewis Dot

Diagram

Carbon p = n = e =

Valence e- = Kernel e- =

Oxygen p = n = e =


Sodium p = n = e =


Neon p = n = e =


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Bohr and Lewis Dot Diagrams (continued)

Element Electron Configuration

# Valence e-

# Kernel e- Bohr Diagram Lewis Dot

Diagram

Fluorine p = n = e =


Argon p = n = e =


Nitrogen p = n = e =


Lead p = n = e =


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Regents Chemistry Name _________________________ Electron Configuration Worksheet Period ____

For the questions 1-10, assume all atoms are neutral. Use the electron configurations to determine the identity of the element and whether it is in the ground or excited state.

Electron Configuration Identity Ground/Excited

1. 2-8-1

2. 2-8-16-3

3. 2-8-2

4. 2-7-8

5. 1-3

6. 2-8-6

7. -18-32-18-4

8. -18-32-17-3

9. 2-7

10. 1-8

Give an electron configuration for the following:

11. Sulfur in its ground state.

12. Helium in an excited state.

13. Give the ground state electron configuration for calcium. _____________________

14. Give the correct electron configuration for the Ca+2 ion. ______________________

15. How many valence electrons are there in atom of bromine? ________

16. How many valence electrons are there in a Cl- ion? ________

17. How many kernel electrons are there in a phosphorus atom? ________

18. How many valence electrons are there in a neon atom? ________

19. How many principal energy levels are there in a iron atom? ________

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20. When atoms of an element are emitting a certain wavelength (or color) of light, it means that

a) the atoms have gained energy and electrons have jumped to an excited state. b) the atoms have gained energy and electrons have fallen back to the ground

state. c) the atoms have lost energy and electrons have fallen back to the ground state. d) the atoms have lost energy and electrons have jumped to an excited state.

Use the emissions spectra results below to answer questions 14 and 15:

Gas A Gas B Gas C Gas D Unknown Gas

21. According to these experimental spectra results, the unknown gas is a mixture of

which gases? ___________

22. The lines on the visible light spectrum for the gases above represent a) electrons jumping to the same excited state or energy level. b) electrons falling back down to their ground state from the same energy level. c) electrons jumping to multiple excited states or energy levels. d) electrons falling back down to their ground state from multiple energy levels.

23. How do the energy and the most probable location of an electron in the third

shell of an atom compare to the energy and the most probable location of an electron in the first shell of the same atom?

a) In the third shell, an electron has more energy and is closer to the nucleus.

b) In the third shell, an electron has more energy and is farther from the nucleus.

c) In the third shell, an electron has less energy and is closer to the nucleus.

d) In the third shell, an electron has less energy and is farther from the nucleus.

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24. An atom of oxygen is in an excited state. When an electron in this atom moves from the third shell to the second shell, energy is

a) emitted by the nucleus b) absorbed by the nucleus c) emitted by the electron d) absorbed by the electron

25. Which electron configuration could represent a strontium atom in an excited

state? a) 2–8–18–7–1 b) 2–8–18–8–1 c) 2–8–18–7–3 d) 2–8–18–8–2

26. Imagine an emission spectrum produced by a container of hydrogen gas.

Changing the amount of hydrogen in the container will change the colors of the lines in the spectrum.

a) True b) False

27. In the previous question, changing the gas in the container from hydrogen to helium will change the colors of the lines occurring in the spectrum.

a) True b) False

28. An absorption spectrum appears as a continuous spectrum interrupted by a

series of dark lines. a) True b) False

29. Emission spectra are characterized by narrow bright lines of different colors.

a) True b) False

*student* *student* mr. dolgos regents chemistry

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student student mr. dolgos regents chemistry