13 ELECTRONS IN ATOMS - Teacher Notes

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13 ELECTRONS IN ATOMS Honors Curriculum
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math/problem-solving

SECTION 13.1 MODELS OF THE ATOM (pages 361–366)

This section summarizes the development of atomic theory. It also explains the significance of
quantized energies of electrons as they relate to the quantum mechanical model of the atom.

The Evolution of Atomic Models (pages 361–363)

1. What are the chemical properties of atoms, ions, and molecules related to?
The properties are related to the arrangement of electrons.

2. Complete the table about atomic models and the scientists who developed
them.

Scientist Model of Atom
Dalton
Thomson The atom is a solid indivisible mass.
Rutherford
The atom is a ball of positive charge with electrons stuck into the ball.
Bohr
Most of an atom’s mass is concentrated in the small, positively charged
nucleus. The electrons surround the nucleus and the rest of the atom is
empty space.
Electrons are arranged in concentric circular paths around the nucleus.

© Prentice-Hall, Inc. 3. The energy level of an electron is the region around the nucleus where
_th_e__e_l_e_c_tr_o_n__is__li_k_e_ly__to__b_e__m__o_v_in_g_____________________________ .

4. Is the following sentence true or false? The electrons in an atom can exist
between energy levels. _________f_a_ls_e__________

5. Circle the letter of the term that completes the sentence correctly. A quantum
of energy is the amount of energy required to

a. move an electron from its present energy level to the next lower one

b. maintain an electron in its present energy level

c. move an electron from its present energy level to the next higher one

6. In general, the higher the electron is on the energy ladder, the
________f_a_r_th_e_r_________ it is from the nucleus.

Addison-Wesley Chemistry Guided Study Workbook 125

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CHAPTER 13, Electrons in Atoms (continued)

The Quantum Mechanical Model (pages 363–364)

7. What is the difference between the previous models of the atom and the modern
quantum mechanical model? _P__re_v_i_o_u_s__m_o__d_e_ls__w_e_r_e__p_h_y_s_ic_a__l _m_o_d_e__ls__b_a_s_e_d__o_n__th_e___
motion of large objects. The quantum mechanical model is a mathematical model.

8. Is the following sentence true or false? The quantum mechanical model of the
atom estimates the probability of finding an electron in a certain position.

__________t_ru_e__________

Atomic Orbitals (pages 364–366)

9. Circle the letter of the term that correctly answers this question. Which name
describes the major energy levels of electrons?

a. atomic orbitals c. quantas

b. quantum mechanical numbers d. principal quantum numbers (n)

10. Principal energy levels are assigned values in order of _______in_c_r_e_a_s_i_n_g_______
energy: n ϭ 1, 2, 3, 4, and so forth.

11. In the quantum mechanical model the regions where electrons are likely
to be found are called _____a__to_m__ic__o_r_b_it_a_ls_____ and are denoted by
_________le_t_te_r_s_________ .

12. Match each diagram below with the name of its p orbital, the px, py, or pz.

zz z

xx x

yy y © Prentice-Hall, Inc.

px py pz
p orbitals

13. Use the diagram above. Describe how the px, py, and pz orbitals are similar.
The p orbitals are similar because they are all dumbbell shaped.

14. Describe how the px, py, and pz orbitals are different. _T_h__e_p__o_r_b_it_a_l_s_h_a_v_e__d_i_ff_e_re__n_t ___
orientations in space. They are all perpendicular to each other.

15. Circle the letter of the formula for the maximum number of electrons that can
occupy a principal energy level. Use n for the principal quantum number.

a. 2n2 b. n2 c. 2n d. n

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SECTION 13.2 ELECTRON ARRANGEMENT IN ATOMS (pages 367–370)

This section shows you how to apply the aufbau principle, the Pauli exclusion principle, and Hund’s
rule to help you write the electron configurations of elements. It also explains why the electron
configurations for some elements differ from those assigned using the aufbau principle.

Electron Configurations (pages 367–369)

1. The ways in which electrons are arranged around the nuclei of atoms are
called ___________e_l_e_c_tr_o_n__c_o_n_f_ig_u_r_a_t_io_n_s_____________ .

Match the name of the rule used to find the electron configurations of atoms with
the rule itself.

____b___ 2. aufbau principle a. When electrons occupy orbitals of
equal energy, one electron enters each
____c___ 3. Pauli exclusion orbital until all the orbitals contain
principle one electron with parallel spins.

____a___ 4. Hund’s rule b. Electrons enter orbitals of lowest
energy first.

c. An atomic orbital may describe at
most two electrons.

5. Look at the aufbau diagram, Figure 13.6 on page 367. Which atomic orbital
is of higher energy, a 4f or a 5p orbital? ___4_f___

6. Fill in the electron configurations for the elements given in the table. Use the
orbital filling diagrams to complete the table.

Element Electron Configurations for Some Selected Elements
H
Orbital filling
Electron

1s 2s 2px 2py 2pz 3s configuration

1s 2

© Prentice-Hall, Inc. He 1s 2

Li 1s 22s1

C 1s 22s 22p 2
N 1s 22s 22p 3

O 1s 22s 22p4
F 1s 22s 22p 5
Ne 1s 22s 22p6
Na 1s 22s 22p 63s 1

Guided Reading and Study Workbook 127

Name ____________________________________ Date __________ Class ___________________ © Prentice-Hall, Inc.

CHAPTER 13, Electrons in Atoms (continued)

7. In the shorthand method for writing an electron configuration, what does a
superscript stand for?
The superscript stands for the number of electrons occupying a given sublevel.

8. In the shorthand method for writing an electron configuration, what does the
sum of the superscripts equal?
The sum equals the number of electrons in the atom.

Exceptional Electron Configurations (page 370)

9. Is the following sentence true or false? The aufbau principle works for
every element in the periodic table. __________f_a_ls_e_________

10. Filled energy sublevels are more ________s_t_a_b_le__________ than partially filled
sublevels.

11. Half-filled levels are not as stable as __________fi_ll_e_d_________ levels, but are
more stable than other configurations.

Reading Skill Practice

Outlining can help you understand and remember what you have read. Prepare an outline of Section
13.2, Electron Arrangement in Atoms. Begin your outline by copying the headings from the textbook.
Under each heading, write the main idea. Then list the details that support, or back up, the main idea.
Do your work on a separate sheet of paper.

The subheads of students’ outlines of the section should be Electron Configurations and Exceptional
Electron Configurations. The section’s main ideas should form the next level of the outline.

SECTION 13.3 PHYSICS AND THE QUANTUM MECHANICAL MODEL

(pages 372–383)

This section explains how to calculate the wavelength, frequency, or energy of light, given two of these
values. It also explains the origin of the atomic emission spectrum of an element.

Light and Atomic Spectra (pages 372–375)

1. Light consists of electromagnetic waves. What kinds of visible and invisible
radiation are included in the electromagnetic spectrum?
The following kinds of radiation are included in the electromagnetic spectrum: radio
waves, microwaves, infrared waves, visible light, ultraviolet waves, x-ray, and gamma
rays.

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2. Match each term describing waves to its definition.

____b___ amplitude a. the distance between two crests

____a___ wavelength b. the wave’s height from the origin to the crest

____c___ frequency c. the number of wave cycles to pass a given point per
unit of time

3. Label the parts of a wave in this drawing. Label the wavelength, the amplitude,
the crest, and the origin.

Wavelength λ Crest

Amplitude Origin

4. Is the following sentence true or false? The frequency and wavelength of all
waves are inversely related. _________t_ru_e___________

5. The product of frequency and wavelength always equals a(n)
_______c_o_n_s_t_a_n_t________ , the speed of light.

6. The units of frequency are usually cycles per second. The SI unit of
cycles per second is called a(n) _______h_e_r_t_z_(_H_z_)_______ .

7. When sunlight passes through a prism, the different wavelengths separate into
a(n) _______s_p_e_c_t_ru__m________ of colors.

© Prentice-Hall, Inc. 8. Put the visible colors in order from light with the longest wavelength and
lowest frequency to light with the shortest wavelength and the highest
frequency.

____2___ orange ____3___ yellow

____4___ green ____6___ indigo

____5___ blue ____1___ red

____7___ violet

9. Look at Figure 13.10 on page 373. The electromagnetic spectrum consists of
radiation over a broad band of wavelengths. What type of radiation has the
lowest frequency? The highest frequency?

Radio waves have the lowest frequency. Cosmic rays have the highest frequency.

10. What happens when an electric discharge is passed through the gas or vapor
of an element?

The element emits light as it is excited by the passage of the electric discharge.

Guided Reading and Study Workbook 129

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CHAPTER 13, Electrons in Atoms (continued)

11. Passing the light emitted by an element through a prism gives the
_____________a_t_o_m__ic__e_m_i_s_s_io_n__s_p_e_c_t_r_u_m______________ of the element.

12. Is the following sentence true or false? The emission spectrum of an element
can be the same as the emission spectrum of another element.
_________f_a_ls_e__________

The Quantum Concept and the Photoelectric Effect (pages 376–379)

13. Planck showed mathematically that the amount of radiant energy (E) absorbed
or emitted by a body is ________p_ro_p__o_rt_io_n__a_l ____ to the frequency of the
radiation: E ϭ h ϫv.

14. What is a small, discrete unit of energy called?
It is called a quantum.

15. What did Albert Einstein call the quanta of energy that is light?
________p_h_o__to_n_s________

16. What is the photoelectric effect?
The photoelectric effect occurs when metals eject electrons called photoelectrons

when light shines on them.

17. Is the following sentence true or false? Albert Einstein recognized that there
is a threshold value of energy below which the photoelectric effect does not
occur. __________tr_u_e__________

An Explanation of Atomic Spectra (pages 379–380)

18. What is the lowest energy level of an electron called? ________g_r_o_u_n_d__s_t_a_te___________
19. Only electrons in transition from _________h_i_g_h_e_r________ to

_________l_o_w_e__r ________ energy levels lose energy and emit light.

Quantum Mechanics (pages 381–382)

20. What does de Broglie’s equation describe?
It describes the wavelength of a moving particle.

21. What does de Broglie’s equation predict?
It predicts that all matter exhibits wavelike motions.

22. Is the following sentence true or false? The new method of describing the
motions of subatomic particles, atoms, and molecules is called quantum
mechanics. _________tr_u_e___________

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