Topic List for Atomic Structure Unit



Honors Chemistry: Atomic Theory/Nuclear Test Review Name_______KEY_______________

Particles of the Atom

✓ proton, neutron, electron…nucleons?

✓ charges, location, masses

✓ mass number, atomic number

✓ charged atoms = ions

Isotopes

✓ same element (protons), different masses (neutrons)

✓ Complete Atomic Designation

✓ Average Atomic Mass

✓ radioactive isotopes

o half-Life

✓ nuclear transmutation reactions

o decay particles: alpha, beta, gamma, positron

o emission/decay v. bombardment

✓ fission v. fusion

✓ E = mc2

History of the Atom (what resulted from each model?)

✓ Greeks

✓ John Dalton

o Atomic Theory (know postulates)

✓ J.J. Thomson

o cathode ray tube

o plum-pudding model

✓ Rutherford

o gold foil experiment

✓ Chadwick

o discovered neturons

✓ Bohr

o planetary model of the atom

✓ Quantum Mechanical Model

o electron cloud model

o orbitals

Light

✓ ground state v. excited state

o absorption of energy ( light emission (emission spectrum)

✓ characteristics of waves

o wavelength, frequency, crest, trough, amplitude

o How does wavelength change v. frequency?

v. energy? …frequency v. energy?

✓ calculations

o c = λf, where c = 3.0 x 108 m/s

o E = hf, where h = 6.63 x 10-34 J s

Electron Configuration

✓ energy levels, types of orbitals, filling order (use Periodic Table)

✓ shorthand notation (using noble gases)

✓ orbital diagrams (filling order)

o aufbau Principle

o Hund’s Rule

o Pauli Exclusion Principle

✓ valence electrons vs. kernel (core) electrons

✓ ion formation (losing/gaining e-) and octet rule

Periodic Table

✓ s-block, p-block, d-block, f-block

✓ charges (+1, +2,…..2-, 1-)

Atomic Structure Review Questions

1. Using your vocabulary and your notes, fill in the following blanks.

Protons are POSITIVELY charged particles in the NUCLEUS of an atom. The protons have a mass of approximately ONE AMU. The number of protons in the nucleus, also called the ATOMIC NUMBER, is responsible for determining the type of atom, or the ELEMENT. The NEUTRONS are also in the nucleus with the protons, together their sum is the MASS NUMBER. Neutrons are almost equal in mass to the protons and are NEUTRAL in charge. NEUTERONS are responsible for creating isotopes. Outside the nucleus are the ELECTRONS which can be gained or lost to produce IONS. Positively charged ion are called CATIONS, while negatively charged ions are called ANIONS.

2. Using your vocabulary and your notes, complete the following table.

|Scientist |Experiment/Observation |Discovery or Major Contribution |Model |

|Dalton |Law of multiple proportions, atoms are indivisible, all atoms |Atomic Theory |[pic] |

| |of an element are the same | | |

| | | |[pic] |

|Thomson |Cathode ray tube |Electrons and + charges | |

| | |(plum-pudding model) | |

| |Gold-Foil Experiment |+ Nucleus; |[pic] |

|Rutherford | |Atom is mostly empty space. | |

| | | | |

| |Electrons have only specific energy levels and distances from |Electrons in ORBIT at fixed distances from |[pic] |

|Bohr |the nucleus that are allowed. |nucleus | |

| | |(planetary model) | |

|Various |Math / probability |Quantum Mechanical Model |[pic] |

| |s-, p-, d-, f-orbitals | | |

3. The element Chemistrium (Ch) has 2 varieties, Ch-110 and Ch-112. Ch-110 has a % abundance of 73%. Find the average atomic mass of Ch.

AAM = (% A)(mass A) + (% B)(mass B)

AAM = (0.73)(110 amu) + (0.27)(112 amu)

AAM = 80.3 amu + 30.24 amu

AAM = 110.54 amu

4. The element rubidium (Rb) has an average atomic mass of 85.468 amu. Rubidium has two common isotopes, 85Rb and 87Rb. The average atomic mass of 85Rb is 85.00 amu and the abundance of is 72.2%, what is the average atomic mass of 87Rb?

AAM = (% A)(mass A) + (% B)(mass B)

85.468 amu = (0.722)(85.00 amu) + (0.278)(x amu)

24.098 = 0.278 x

x = 86.68 amu = 87Rb

5. Complete the following table:

|Atomic # |Protons |Neutrons |Electrons |Mass # |

|composition |helium nucleus |fast-moving electron |high-energy wave |+ charged e- |

|symbol | |[pic] |[pic] |[pic] |

| |[pic] | | | |

|charge |2+ |1- |0 |1+ |

|approx. mass |~ 4 amu |~0 amu |0 amu |~0 amu |

| | |(0.00054 amu) | |(0.00054 amu) |

|approx. energy |high |low |medium-low |low |

|penetrating power |low |moderate |very high |moderate |

6. Complete the following transmutation reactions:

a. Radon-225 decays by beta emission:

[pic]

b. Samarium-147 decays by alpha emission:

[pic]

c. Thulium-186 undergoes electron capture:

[pic]

d. Aluminum-25 undergoes positron emission:

[pic]

e. Americium-240 decays by alpha emission and then beta emission:

[pic]

f. An alpha particle bombards an phosphorus-32 atom, producing a new atom and a neutron:

[pic]

g. An alpha particle bombards a fluorine-19 atom, producing a new atom and a proton:

[pic]

7. What is the definition of half-life? The time it takes for half of a radioactive element to decay

8. The half-life of a substance is 9.7 ms. How long will it take for 25 % of the original amount to remain?

100% ( 50% ( 25% = 2 half-lives 9.7 ms x 2 half-lives = 19.4 ms ( 19 ms

9. If you originally had 100. g of a substance, how much will you have left after 4 half-lives? After 5 half-lives?

100. g ( 50.0 g ( 25.0 g ( 12.5 g ( 6.25 g ( 3.13 g

10. A given substance has a half-life of 2.0 x 109 years. If you buy 150. g of this substance, how much will be left after 12,000,000,000 years?

12 x 109 yr / 2.0 x 109 yr = 6 t1/2 150 (1/2)6 = 2.3438 ( 2.34 g

11. What is the half-life of a substance, if after 5000 years, a 1800 g sample now masses 450 g?

1800 g ( 900 g ( 450 g = 2 t1/2 5000 yr / 2 = 2500 yr for every t1/2

12. The mass of a thorium-232 nuclide is 232.011 amu. What is the mass defect (in amu)?

[pic]

[pic]

13. Calculate the energy produced by the thorium-232 nuclide (in J).

[pic]

[pic]

14. Draw two light waves: one with a long wavelength and one with a short wavelength.

Wavelength is inversely related to frequency and energy. So, a wave with a long wavelength would have both a lower frequency and a lower energy. The wave with a short wavelength would have a comparably larger frequency and energy. Remember that frequency and energy are directly related.

Compare the frequency and energy of your two waves.

15. The following diagrams show energy changes within an atom as an electron either absorbs or emits energy.

a. Which diagram shows energy being absorbed?

Diagram I: energy is absorbed, causing an e- to be

promoted from level 2 to level 5 (excited)

b. …emitted as light (given off)?

Diagram II: light is emitted as the e- falls from level 4

back down to level 2

I. II.

c. Which diagrams shows the greatest change in energy?

Diagram I: the difference in energy from levels 2 to 5 is

greater than from levels 4 to 2.

d. Assuming light is involved in both energy changes,

which diagram illustrates light with a longer wavelength? Why?

Diagram II: wavelength is inversely related to energy, so because this diagram has the smaller energy change, its resulting wave will have a longer wavelength

16. A photon of light has a wavelength of 3.20 x 103 cm. Find… λ = 3.20 x 101 or 32 m (must use m for these eq.)

a. the frequency of the radiation. b. the energy of the photon.

c = λ· f E = h·f

3.0 x 108 m/s = 32 m (f) E = 6.63 x 10-34 J·s (9,375,000 Hz)

f = 9.4 x 106 Hz E = 6.2 x 10-27 J

17. Write the longhand and shorthand electron configurations for the following atoms: valence e- in red

Longhand Shorthand

a) boron B = 1s22s22p1 B = [He] 2s22p1

b) nitrogen N = 1s22s22p3 N = [He] 2s22p3

c) cadmium Cd = 1s22s22p63s23p64s23d104p65s24d10 Cd = [Kr] 5s24d10

d) sodium ion Na+ = 1s22s22p6 Na+ = [He] 2s22p6 or [Ne]

e) phosphide ion P3- = 1s22s22p63s23p6 P3- = [Ne] 3s23p6 or [Ar]

18. For 18a and 18b, draw an orbital diagram below. You can use boxes for the orbitals and arrows for the electrons.

18a. [pic]

18b. [pic]

19. Look at your periodic table. For each of the following elements, answer the following:

a. How many valence electrons does this element have?

b. …core electrons?

c. How many electrons would this element gain or lose to become more stable? Specify gain or lose.

d. What charge would this element have after following the octet rule?

|H |N |O |Br |Mg |Kr | |a. |1 |5 |6 |7 |2 |8 | |b. |0 |2 |2 |28 |10 |28 | |c. |loses 1e- |gains 3 e- |gains 2 e- |gains 1 e- |loses 1e- |neither gains nor loses | |d. |1+ |3- |2- |1- |2+ |0 | |

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