Models of the Atom

(11 Days)

 

Tentative Dates	Topic(s)	Reading Chapters 5 and 28	Homework
4/14	Thomson's Model of the Atom / Cathode Ray Tubes	Early Models of the Atom, Just How Small Is an Atom?, Electrons pp. 107 - 110	Supplemental Problems: 1 - 6
4/15	Rutherford's Model of the Atom	Protons and Neutrons, The Atomic Nucleus pp. 110 - 112	Supplemental Problems: 7 - 11
4/16	Isotopes and Avg. Mass	Atomic Number, Mass Number, Isotopes, Atomic Mass pp. 113 - 120	Supplemental Problems: 12 - 15
4/17	Light Basics	Light and Atomic Spectra, The Quantum Concept, pp. 372 - 379	Supplemental Problems: 16 - 21
4/21	Bohr's Model of the Atom	An Explanation of Atomic Spectra, pp. 379 - 382	Practice Problems: 11 - 13, pp. 375 & 379 Supplemental Problems: 22
4/22	Atomic Orbitals and Electron Configurations	Evolution of Atomic Models, The Quantum Mechanical Model, pp. 363 - 366	Supplemental Problems: 23 - 27
4/23	Electron Configurations and Energy Diagrams	Atomic Orbitals, pp. 364 - 366	Supplemental Problems: 28 - 33
4/24	The Periodic Table and Electron Configurations	Electron Configurations, pp. 367 - 369	Supplemental Problems: 34 - 38
4/25	Periodic Trends: Atomic and Ionic Size Periodic Trends: Ionization Energy	Trends in Atomic Size, pp. 398 - 401 Trends in Ionization Energy, pp. 401 - 403	Concept Practice: 16, 18, 20, 22, 24, p 409 - 410 Supplemental Problems 39 - 42
4/28	Review	Concept Summaries for Chapters 13 and 14	Study!!
4/29	Models of the Atoms Test	Pre-Lab: Qualitative Analysis: Relative Solubilities	Pre-Lab: Qualitative Analysis: Relative Solubilities

Supplemental Problems:

1) In your own words, state the main ideas of Dalton's atomic theory.

2) Use Figure 5.2 on page 108 to find the diameter ( in cm) of a copper atom.

3) Describe the gas discharge tube shown in Figure 5.4 on page 109. (Use the words cathode, anode, and cathode rays in your description.) How does it behave?

4) In 1897, the English Scientist J.J. Thomson used gas discharge tubes to make the first measurements of the particle now know as the electron.

	a)	Use Figure 5.5 on page 110 to describe the equipment Thomson used to make his measurements.
	b)	What was the effect on cathode rays of using different metals for anodes and cathodes in the gas discharge tubes?
	c)	What was the effect on cathode rays of using different gases in the discharge tubes?

5) What evidence did Thomson have for the following statements?

	a)	Electrons have a negative charge.
	b)	Atoms of all elements contain electrons.

6) A single electron has a mass of 9.1 x 10^-28 gram.

	a)	How many electrons would be needed to furnish a mass of one gram?
	b)	What would be the mass of a mole of electrons?

7) As a result of his experiments with gas discharge tubes, Thomson formed a model of the atom that included both positive charges (protons) and negative charges (electrons).

	a)	Neutral helium atoms contains how many protons? how many electrons?
	b)	An He+ ion contains how many protons? how many electrons?
	c)	An He- ion contains how many protons? how many electrons?

8) Which would have a larger charge-to-mass ratio, a Na⁺ or a K⁺ ion?

9) Elements numbers 9 (fluorine) and 17 (chlorine) form F^- and Cl^- ions. Will the charge-to-mass ratio for these ions be the same? Explain.

10) Shortly after Thomson's model of the atom was created, it was improved upon by Ernest Rutherford. Study Figure 5.6 on page 111.

	a)	Describe the equipment Rutherford used in his experiment.
	b)	What were the results of his experiment?
	c)	How did Rutherford explain the results of his experiment?
	d)	What is different about Rutherford's model of the atom from Thomson's model?

11) Platinum and zinc have the same number of atoms per cubic centimeter. Would thin sheets of these elements differ in the way they scatter alpha particles? Why or why not?

12) Fill in the blanks in the table below. Assume the atoms are neutral.

13) List the number of protons, neutrons, and electrons in each pair of isotopes:

a)

,

b)

,

14) Copper occurs naturally in two isotopes, ⁶³Cu (69%) and ⁶⁵Cu (31%). Show how this accounts for the molar mass listed for copper.

15) Use Table 5.3 on page 119 to calculate the average atomic mass of chlorine.

16) Describe Rutherford's model of the atom. List an advantage and a disadvantage of the model. (i.e. What did Rutherford's model successfully explain about the atom, and what didn't make sense about his model?)

17) The speed of a wave is equal to its frequency multiplied by its wavelength. Sitting on a pier in Florence, you count three ocean waves pass a given point every ten seconds. The distance between each wave is approximately 1.5 meters. Calculate the speed of the waves in km/hr.

18) The FM radio station, KZEL, broadcasts its radio signal at a frequency 96.1 of Megahertz (10⁶ Hz). KUGN is an AM radio station that broadcasts at 590 Kilohertz (Kilo = 10³ Hz) the relationship Speed of Light = Frequency xWavelength (given that the speed of light is 3.00 x 10⁸ m/s), calculate the length of these radio waves.

19) The Spectrum of Electromagnetic Radiation (Light) is given in Figure 13.10 on page373. The spectrum lists nine types of electromagnetic radiation.

	a)	List the types of electromagnetic radiation and give their range of frequencies.
	b)	Given that the speed of all these different forms of light = 3.00 x 108 m/s, calculate the length of a typical radio, infrared, ultraviolet, and X-ray.

20) One line in the lithium spectrum has an energy of 3.27 x 10^-19 J. Determine the frequency of this line. Refer to the diagram of the electromagnetic spectrum on the fourth page of the reading to find what part of the spectrum the line would appear in. (h = 6.6262 x 10 ^-34 J*sec)

21) When hydrogen gas is electrically excited in a discharge tube and viewed through a really good spectroscope, 5 lines are seen. The lines have wavelengths indicated in the table below. Calculate the frequencies and energies of each of the spectral lines. (Remember c = 3.00 x 10⁸ m/sec, and h = 6.6262 x 10 ^-34 J*sec)

22) A photon has an energy of 7.0 x 10 ^-23 J.

	a)	Calculate its frequency.
	b)	Calculate its wavelength.
	c)	Use the diagram of the electromagnetic spectrum to figure out the type of light the photon is.

23) The modern description of the 1s orbital of the hydrogen atom, is similar in some respects to a description of the holes in a much-used dart board. For example, the "density" of dart holes is constant anywhere on a circle centered about the bull's eye, and the "density" of dart holes reaches zero only at a very long distance from the bull's eye. What are the corresponding properties of a 1s orbital?

24) In light of your answer to question 8, point out erroneous features of the of the following models of a hydrogen atom.

	a)	a solid rubber ball
	b)	a basketball
	c)	a "solar system" atom with the electron circling the nucleus at a fixed distance

25) Sometimes a pair of balloons tied together is used to represent a "p"orbital. List two advantages and two disadvantages of this model.

26) Show in a rough way how electron probability varies in a 1s orbital. Plot probability on the y-axis and distance from the nucleus on the x-axis.

27) Which of the following statements about orbitals is FALSE?

Orbitals are

a)	distributed in space around the nucleus.	b)	regions in which electrons are likely to be found.
c)	of different sizes and shapes.	d)	able to show the path of the electron.
e)	part of one model for atomic structure.

28) The energies of electrons are "quantized." Explain this.

29) How many total orbitals are in the following:

a)	the 1st energy level (n = 1)	b)	the 2nd energy level (n = 2)
c)	the 3rd energy level (n = 3)	d)	the 3 p sublevel
e)	the 2 s sublevel	f)	the 4 d sublevel

30) A hydrogen atom has one electron in a 1s orbital. Draw a picture on an x, y, z coordinate graph. (See 13.4 on page 365 as a model.)

Repeat this for the following atoms:

Lithium (2 electrons in a 1s orbital and 1 electron in a 2s orbital)

Carbon (2 electrons in a 1s, 2 electrons in a 2s, and 2 electrons in a 2p orbital)

Neon (2 electrons in a 1s, 2 electrons in a 2s, and 6 electrons in a 2p orbital)

31) Which of the following orbital designations are invalid?

a) 4s

b) 3f

c) 2d

d) 3d

32) What is the maximum electrons that can go into each of the following sublevels?

a) 2s

b) 4f

c) 3p

d) 2p

33) What must be done to an atom to change its 2s electron to a 3s electron? What happens when an atom with a 3s electron becomes one with a 2s electron?

34) Consider these two electron populations for neutral atoms:

A. 1s2 2s2 2p6 3s1

B. 1s2 2s2 2p6 6s1

Which of the following is FALSE?

a) Energy is required to change A to B.

b) A represents a sodium atom.

c) A and B represent different elements.

d) Less energy is required to remove on electron from B than from A.

35) Name the element that corresponds to each of the following electron configurations:

a)	1s2	b)	1s2 2s1
c)	1s2 2s2 2p1	d)	1s2 2s2 2p3
e)	1s2 2s2 2p6 3s2 3p6 4s1

36) Name the atom for each of the electron configurations below. Assume all lower energy orbitals to be full and the atom to be in its lowest energy state.

a) 2s1

b) 3p4

c) 3s1

d) 3p6

e) 4p1

f) 2p1

g) 1s2

h) 6s1

i) 5p5

37) Write the energy diagrams for the elements indicated.

a)	element with atomic # 9	b)	element with atomic # 13
c)	element with atomic # 20	d)	element with atomic # 7

38) Write the electron configurations and energy diagrams for the following atoms:

a)	Lithium	b)	Fluorine
c)	Rubidium	d)	Titanium

 39) Name the atoms for each of the electron configurations below. Assume all lower energy levels are filled and the atom is in its lowest energy state.

a)	3s2	b)	5p4
c)	2p6	d)	3p5
e)	3d1	f)	6s2

40) State whether the atoms listed above are noble gases, representative elements, transition metals or inner transition metals. You might need to look up the definitions of these terms in your text.

a)	Lithium	b)	Fluorine
c)	Rubidium	d)	Titanium

41) Draw energy diagrams and indicate the electron configurations for the following ions:

a)	Na+1	b)	Mg 2+
c)	O 2-	d)	F -1

42) What do you notice about the diagrams and configurations in problem 41?

43) The periodic table as it appears in most representations is altered so that it fits on a single page. Draw an outline of the periodic table showing all elements (including elements 57-71 and 89-103 in their proper place.

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