Name Chemistry I: Atomic Structure: Unit Worksheet Period ... · Chemistry I: Atomic_Structure_BOOK_WS_2012[1] 1 ... The modern process of discovery about atoms began with the theories

Chemistry I: Atomic_Structure_BOOK_WS_2012[1] 1 September 12

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Name Chemistry I: Atomic Structure: Unit Worksheet Period Date ATOMIC STRUCTURE SECTION 4.1 DEFINING THE ATOM (pages 101–103) This section describes early atomic theories of matter and provides ways to understand the tiny size of individual atoms. Early Models of the Atom

1. Democritus, who lived in Greece during the fourth century B.C., suggested that

matter is made up of tiny particles that cannot be divided.

He called these particles ______________________ .

2. The modern process of discovery about atoms began with the theories of an

English schoolteacher named ______________________ . 3. Circle the letter of each sentence that is true about Dalton’s atomic theory.

a. All elements are composed of tiny, indivisible particles called atoms.

b. An element is composed of several types of atoms.

c. Atoms of different elements can physically mix together, or can chemically

combine in simple, whole-number ratios to form compounds.

d. Chemical reactions occur when atoms are separated, joined, or rearranged;

however, atoms of one element are never changed into atoms of another

element by a chemical reaction.

4. Suppose you could grind a sample of the element copper into smaller and smaller

particles. The smallest particle that could no longer be divided, yet still has the chemical

properties of copper, is _________________________________ .

5. About how many atoms of copper when placed side by side would form a line 1 cm

long? ______________________

SECTION 4.2 STRUCTURE OF THE NUCLEAR ATOM (pages 104–108) This section describes the experiments that led to the discovery of subatomic particles and their properties. Subatomic Particles



1. How is the atomic theory that is accepted today different from Dalton’s atomic

theory?

2. Which subatomic particles carry a negative charge? ______________________

Match each term from the experiments of J. J. Thomson with the correct description.

_______ 3. anode a. an electrode with a negative charge

_______ 4. cathode b. a glowing beam traveling between charged

electrodes

_______ 5. cathode ray c. an electrode with a positive charge

_______ 6. electron d. a negatively charged particle

7. The diagram shows electrons moving from left to right in a cathode-ray tube. In which direction do the electrons flow?

8. Thomson observed that the production of cathode rays did not depend on the kind

of gas in the tube or the type of metal used for the electrodes. What conclusion did he

draw from these observations?



9. What two properties of an electron did Robert Millikan determine from his

experiments?

10. Circle the letter of each sentence that is true about atoms, matter, and electric

charge.

a. All atoms have an electric charge.

b. Electric charges are carried by particles of matter.

c. Electric charges always exist in whole-number multiples of a single basic unit.

d. When a given number of positively charged particles combine with an equal

number of negatively charged particles, an electrically neutral particle is formed.

11. Circle the letter next to the number of units of positive charge that remain if a

hydrogen atom loses an electron.

a. 0 b. 1 c. 2 d. 3

12. The positively charged subatomic particle that remains when a hydrogen atom

loses an electron is called ______________________ .

13. What charge does a neutron carry? ______________________ .

14. Complete the table about the properties of subatomic particles.ud that electrons

must be parts of the atoms of all elements.

Properties of Subatomic Particles

Particle Symbol Relative Electric

Charge Relative Mass (Proton = 1)

Actual Mass (g)

Electron e- or e-1 9.00 x 10-28

Proton p+ 1.67 x 10-24

Neutron no 1.67 x 10-24

0 1



The Atomic Nucleus (pages 106–108) 15. True or false? An alpha particle has a double positive charge because it is a helium

atom that has lost two electrons. ______________________

16. Explain why in 1911 Rutherford and his coworkers were surprised when they shot a

narrow beam of alpha particles through a thin sheet of gold foil.

17. Circle the letter of each sentence that is true about the nuclear theory of atoms

suggested by Rutherford’s experimental results.

a. An atom is mostly empty space.

b. All the positive charge of an atom is concentrated in a small central region

called the nucleus.

c. The nucleus is composed of protons.

d. The nucleus is large compared with the atom as a whole.

e. Nearly all the mass of an atom is in its nucleus.

SECTION 4.3 DISTINGUISHING AMONG ATOMS (pages 110–119) This section explains how atomic number identifies an element; how to use atomic number and mass number to find the number of protons, neutrons, and electrons in an atom; how isotopes differ; and how to calculate average atomic mass. Atomic Number Circle the letter of the term that correctly completes the sentence. 1. Elements are different because their atoms contain different numbers of _______ .

a. electrons b. protons c. neutrons d. nuclei



2. Complete the table showing the number of protons and electrons in atoms of six elements.

Atoms of Six Elements

Name Symbol Atomic # # of p+ # of e-

Hydrogen H 1

Helium He 2

Lithium Li 3

Boron B 5

Carbon C 6

Oxygen O 8 Mass Number (pages 111–112) 3. The total number of protons and neutrons in an atom is its _____________________

4. What is the mass number of a helium atom that has two protons and

two neutrons? ______________________

5. How many neutrons does a beryllium atom with four protons and a mass number of

nine have? ______________________

6. Place the labels chemical symbol, atomic number, and mass number in the

shorthand notation below.

22

10 Ne

7. Show the abbreviated isotopic symbol for the above atom

8. How many protons, neutrons, and electrons are in the atom discussed in Questions 6

and 7? Protons: Neutrons: Electrons:

2



Isotopes (pages 112–113) 9. How do atoms of neon-20 and neon-22 differ?

10. Neon-20 and neon-22 are called ______________________

11. True or false? Isotopes are chemically alike because they have identical numbers of

protons and electrons. ______________________

Match the designation of each hydrogen isotope with its commonly used name.

_______ 12. hydrogen-1 a. tritium

_______ 13. hydrogen-2 b. hydrogen

_______ 14. hydrogen-3 c. deuterium

Atomic Mass (pages 114–117)

15. Why is the atomic mass unit (amu), rather than the gram, usually used to express

atomic mass?

16. What isotope of carbon has been chosen as the reference isotope for atomic mass

units?

What is the defined atomic mass in amu of this isotope?

17. True or false? The atomic mass of an element is always a whole number of atomic

mass units. ______________________



18. Circle the letter of each statement that is true about the average atomic mass of an

element and the relative abundance of its isotopes.

a. In nature, most elements occur as a mixture of two or more isotopes.

b. Isotopes of an element do not have a specific natural percent abundance.

c. The average atomic mass of an element is usually closest to that of the

isotope with the highest natural abundance.

d. Because hydrogen has three isotopes with atomic masses of about 1 amu,

2 amu, and 3 amu, respectively, the average atomic mass of natural hydrogen is

2 amu.

19. Circle the letter of the correct answer.

When chlorine occurs in nature, there are three atoms of chlorine-35 for every one

atom of chlorine-37. Which atomic mass number is closer to the average atomic mass

of chlorine?

a. 35 amu b. 37 amu

The Periodic Table—A Preview (page 118) 20. In the periodic table, the elements are organized into groups based on ______________________________________________________________ . 21. What are the horizontal rows in the periodic table called?

Main heads should be Atomic Number, Mass Number, Isotopes, and Atomic Mass. Subheads should

Reading Skill Practice Outlining can help you understand and remember what you have read. Prepare an outline of Section 4.3, Distinguishing Among Atoms. Begin with the headings in the textbook. Under each heading, write the main idea. Then list the details that support the main idea. Do your work on a separate sheet of paper and staple to the back of the WS packet. 10 pts EXTRA



SECTION 5.1 MODELS OF THE ATOM (pages 127–132) 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 Development of Atomic Models (pages 127–128) 1.Complete the table about atomic models and the scientists who developed them.

Models of Atom

Dalton

Thomson

Rutherford

Bohr

2. True or false? The electrons in an atom can exist between energy levels. ________ The Bohr Model (pages 128–129)

3. What is a small, discrete unit of energy called?

4. 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

5. In general, the higher the electron is on the energy ladder, the__________________

it is from the nucleus.



The Quantum Mechanical Model (page 130-132) 6. What is the difference between the previous models of the atom and the modern

quantum mechanical model?

____________________________________

7. True or false? The quantum mechanical model of the atom estimates the probability

of finding an electron in a certain position.______________________

Atomic Orbitals (pages 131–132)

8. Circle the letter of the term that correctly answers this question. Which name

describes the major energy levels of electrons?

a. atomic orbitals b. quantum mechanical numbers

c. quantas d. principal quantum numbers (n)

9. Principal energy levels are assigned values in order of ___________energy: n =1, 2,

3, 4, and so forth.

10. In the quantum mechanical model the regions where electrons are likely to be

found are called ______________________ and are denoted by

11. Use the diagram above. Describe how the px, py , and pz orbitals are similar.



12. Describe how the px, py , and pz orbitals are different.

13. 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. nelectron follows

around the nucleus.

SECTION 5.2 ELECTRON ARRANGEMENT IN ATOMS (pages 133–136) 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 133–135) 1. The ways in which electrons are arranged around the nuclei of atoms are called ___________________________________________ . Match the name of the rule used to find the electron configurations of atoms with the rule itself.

_______ 2. aufbau principle

a. When electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with parallel spins.

_______ 3. Pauli Exclusion Principle b. Electrons enter orbitals of lowest energy

first

_______ 4. Hund’s rule c. An atomic orbital may describe at most two

electrons.

5. Look at the aufbau diagram, Figure 5.7 on page 133. Which atomic orbital is of higher energy, a 4f or a 5p orbital?



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

Electron Configurations for Some Selected Elements

Element Orbital filling Electron configuration

x y z

1s 2 2 2 2 3s p p p s

1s1

He x y z

1s 2 2 2 2 3s p p p s

x y z

1s 2 2 2 2 3s p p p s

1s22s1

C x y z

1s 2 2 2 2 3s p p p s

x y z

1s 2 2 2 2 3s p p p s

1s22s22p3

O x y z

1s 2 2 2 2 3s p p p s

x y z

1s 2 2 2 2 3s p p p s

1s22s22p5

Ne x y z

1s 2 2 2 2 3s p p p s

x y z

1s 2 2 2 2 3s p p p s

1s22s22p63s1

7. In the shorthand method for writing an electron configuration, what does a

superscript stand for?



8. In the shorthand method for writing an electron configuration, what does the sum of

the superscripts equal?

Exceptional Electron Configurations (page 136)

9. True or false? The aufbau principle works for every element in the periodic table.

______________________

10. Filled energy sublevels are more ______________________ than partially filled

sublevels.

11. Half-filled levels are not as stable as ______________________ levels, but are

more stable than other configurations.

SECTION 5.3 PHYSICS AND THE QUANTUM MECHANICAL MODEL (pages 138–146) 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 (pages 138–140) The superscript stands for the number of electrons occupying a given sublevel. The subheads of students’ outlines of the section should be Electron Configurations and Exceptional

2. The units of frequency are usually cycles per second. The SI unit of cycles per

second is called a(n) ______________________ .

3. The product of wavelength and frequency always equals a(n) _______________ the

speed of light.

Reading Skill Practice the number of electrons in the atom. Outlining can help you understand and remember what you have read. Prepare an outline of Section 5.2, 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. 10 pts Extra



4. True or false? The wavelength and frequency of all waves are inversely proportional

to each other. ______________________

5. Light consists of electromagnetic waves. What kinds of visible and invisible radiation

are included in the electromagnetic spectrum?

6. When sunlight passes through a prism, the different wavelengths separate into a (n)

______________________ of colors.

7. Put the visible colors in order of frequency. 1= lowest energy; 6= highest energy

_______ orange _______ violet

_______ green _______ yellow

_______ blue _______ red

8. Look at Figure 5.10 on page 139. The electromagnetic spectrum consists of radiation

over a broad band of wavelengths. What type of radiation has the lowest frequency?

The highest frequency?

Atomic Spectra (page 141)

9. What happens when an electric current is passed through the gas or vapor of an

element?

10. Passing the light emitted by an element through a prism gives the

_______________________ of the element.

11. True or false? The emission spectrum of an element can be the same as the

emission spectrum of another element.______________________



An Explanation of Atomic Spectra (pages 142–143)

12. What is the lowest possible energy of an electron called? ____________________

13. Only electrons moving from __________________ to _________________ energy

levels lose energy and emit light.

Quantum Mechanics

14. What did Albert Einstein call the quanta of energy that is light? _______________

15. What did de Broglie’s equation predict about the behavior of particles?

16. True or false? The new method of describing the motions of subatomic particles,

atoms, and molecules is called quantum mechanics. ______________________

17. True or false? de Broglie’s conclusions were supported by experimental evidence.

______________________

18. Does the Heisenberg uncertainty principle apply to cars and airplanes?

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Name Chemistry I: Atomic Structure: Unit Worksheet Period ... · Chemistry I: Atomic_Structure_BOOK_WS_2012[1] 1 ... The modern process of discovery about atoms began with the theories