Glencoe Science
Chapter Resources
Properties of Atoms and the Periodic Table Includes: Reproducible Student Pages ASSESSMENT
TRANSPARENCY ACTIVITIES
✔ Chapter Tests
✔ Section Focus Activity
✔ Chapter Review
✔ Teaching Transparency Activity ✔ Assessment Transparency Activity
HANDS-ON ACTIVITIES ✔ Lab Worksheets for each Student Edition Activity
Teacher Support and Planning
✔ Laboratory Activities
✔ Content Outline for Teaching
✔ Foldables–Reading and Study Skills activity sheet
✔ Spanish Resources ✔ Teacher Guide and Answers
MEETING INDIVIDUAL NEEDS ✔ Directed Reading for Content Mastery ✔ Directed Reading for Content Mastery in Spanish ✔ Reinforcement ✔ Enrichment ✔ Note-taking Worksheets
Name
Date
Directed ContentReading for MasteryMastery Content
Class
Overview Properties of Atoms and the Periodic Table
Directions: Complete the concept map using the terms in the list below. Terms can be used more than once. protons
periodic table
electrons
neutrons
have a mass number equal to the sum of
are made up of
1.
and
Meeting Individual Needs
Atoms
are organized as elements in the
5.
4.
2. and
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
and
6.
3.
Directions: complete the following sentences by underlining the correct words in parentheses. 7. An element is matter that is composed of one type of (atom/quark). 8. The unit of measurement used for atomic particles is the (atom size/atomic mass unit). 9. Atoms of the same element that have different numbers of neutrons are called (isotopes/electron clouds). 10. In the periodic table, elements are arranged by increasing atomic (power/number). 11. An electron dot diagram uses the symbol of an element and dots to represent the (quarks/electrons) in the outer energy level.
Properties of Atoms and the Periodic Table
19
Name
Date
Directed Reading for Content Mastery
Section 1
■
Section 2
■
Class
Structure of the Atom Masses of Atoms
Directions: Use the terms below to complete the following paragraphs about atoms , atomic mass, and isotopes. Terms may be used more than once. six number electrons isotopes electron cloud neutron(s) proton(s) mass quarks six protons The electron has very little mass compared to the 1. ________________ or many 3. ________________ and 4. ________________ it has. The sum of the protons and neutrons is the mass 5. ________________ of an atom. The number of neutrons in an atom can be found by subtracting the atomic number from the 6. ________________ number. The mass of the atom is so small that there is a measure called the atomic 7. ________________ unit designated by amu. 8. ________________ and 9. ________________ make up the nucleus and are made up of 10. ________________. There are 11. ________________ uniquely different quarks. 12. ________________ are found in an area around the nucleus called the 13. ________________. The nuclei of all atoms of a given element always have the same number of 14. ________________. They will also have the same number of 15. ________________ around the nucleus. Some atoms may have more or fewer 16. ________________ than will other atoms of the same element. Atoms of the same element with different numbers of neutrons are called 17. ________________. Every atom of carbon must contain 18. ________________ but some contain six neutrons and others have eight neutrons.
20 Properties of Atoms and the Periodic Table
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Meeting Individual Needs
2. ________________. The mass of the atom depends on the nucleus and how
Name
Date
Directed Reading for Content Mastery
Section 3
■
Class
The Periodic Table
Periodic Table of the Elements
Key 1 2 3 4
H Hydrogen 1.008
2
3
4
7
Carbon 12.011
2
13
14
15
16
5
6
7
8
He
17
Helium 4.003
9
10
Li
Be Beryllium 9.0122
B
C
N
O
F
Ne
Boron 10.81
Carbon 12.011
Nitrogen 14.007
Oxygen 15.999
Fluorine 18.998
Neon 20.180
11
12
13
14
15
16
17
18
Al
Si
P
S
Cl
Ar
Aluminum 26.98
Silicon 28.086
Phosphorus 30.974
Sulfur 32.06
Chlorine 35.453
Argon 39.948
Na
Mg
Sodium 22.990
Magnesium 24.305
3
4
5
6
7
8
9
10
11
19
20
21
22
23
24
25
26
27
28
29
30
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
Iron 55.847
Cobalt 58.9332
Nickel 58.693
Copper 63.546
Zinc 65.39
Gallium 69.72
Germanium 72.61
Arsenic 74.922
Selenium 78.96
Bromine 79.904
Krypton 83.80
K
Ca
Sc
Ti
V
Potassium 39.098
Calcium 40.078
Scandium 44.956
Titanium 47.88
Vanadium 50.94
38
39
40
Sr
Y
Zr
Nb
Strontium 87.62
Yttrium 88.9059
Zirconium 91.224
Niobium 92.91
57
56
La
Cs
Ba
Cesium 132.905
Barium 137.327
Lanthanum 138.906
Chromium Manganese 51.996 54.938
41
Rb Rubidium 85.468
55
6
C
Lithium 6.941
37
5
18
Atomic number Element's symbol Element's name Atomic mass
6
1
72
42
43
44
Mo
Tc
Ru
Molybdenum Technetium Ruthenium 97.907 101.07 95.94
73
74
75
76
45
47
31
48
32
33
36
49
50
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
Palladium 106.42
Silver 107.868
Cadmium 112.41
Indium 114.82
Tin 118.710
Antimony 121.757
Tellurium 127.60
Iodine 126.904
Xenon 131.29
83
52
35
Rh
80
51
34
Rhodium 102.906
77
46
12
84
53
54
78
79
81
82
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
Hafnium 178.49
Tantalum 180.95
Tungsten 183.85
Rhenium 186.207
Osmium 190.2
Iridium 192.22
Platinum 195.08
Gold 196.967
Mercury 200.59
Thallium 204.383
Lead 207.2
Bismuth 208.98
Polonium 208.982
Astatine 209.987
85
Radon 222.018
86
87
88
89
104
105
106
107
108
109
110
111
112
114
116
118
Fr
Ra
Rf
Db
Sg
Bh
Hs
Mt
Uun
Uuu
Uub
Uuq
Uuh
Uuo
Francium 223.020
Radium 226.025
Ac Actinium 227.028
Rutherfordium (261)
Dubnium (262)
Seaborgium (263)
Bohrium (262)
Hassium (265)
Meitnerium (266)
Ununnilium (269)
Unununium (272)
Unumbium (277)
Ununquadium (285)
Ununhexium (289)
Ununodium (293)
Rare-Earth Elements 58
Lanthanide Series
Ce Cerium 104.115
90
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Actinide Series
59
60
61
62
Pr
Nd
Pm
Sm
Praseodymium Neodymium Promethium Samarium
150.36
63
64
Eu
Gd
Europium Gadolinium 151.965 157.25
140.908
144.24
144.913
91
92
93
94
95
Np
Pu
Am
Th
Pa
U
Thorium 232.038
Protactinium 231.036
Uranium 238.029
Neptunium Plutonium Americium 237.048 244.064 243.061
96
Cm Curium 247.070
65
Tb Terbium 158.925
66
67
Dy
Ho
Dysprosium Holmium 162.50 164.93
68
69
70
71
Er
Tm
Yb
Lu
Erbium 167.26
Thulium 168.934
Ytterbium 173.04
Lutetium 174.967
97
98
99
100
101
102
Bk
Cf
Es
Fm
Md
No
Berkelium Californium Einsteinium Fermium Mendelevium Nobelium 247.070 251.080 252.083 257.095 259.101 258.099
103
Lr Lawrencium 260.105
Directions: Use the periodic table above to answer the following questions. 1. List two types of information that are given in each box of this periodic table. a. b. 2. In this table, where are the metals located? 3. Where are the nonmetals located? 4. What are the elements in Groups 3 through 12 called? 5. What are the elements called that are next to the stairstep-shaped line on the right side of the table? 6. What do we call the letter or letters that represents an element?
7. How many elements are included in the modern periodic table? 8. What name is given to the elements in Group 18? Properties of Atoms and the Periodic Table
21
Meeting Individual Needs
1—New designation
Name
Date
Directed Reading for Content Mastery
Class
Key Terms Properties of Atoms and the Periodic Table
Directions: Match the term in Column II with the definition in Column I. Write the letter of the correct term in the blank at the left. Column I 1. sum of the number of protons and neutrons in the nucleus
3. positively charged center of an atom 4. vertical column in the periodic table 5. neutral particles in the nucleus of an atom 6. weighted average mass of the mixture of its isotopes
a. nucleus b. electrons c. protons d. neutrons e. quark f. atomic number g. mass number
7. positively charged particles in an atom 8. table of the elements arranged according to repeated changes in properties 9. represents the electrons in the outer energy level of an element
h. isotope i. average atomic mass j. electron cloud
10. negatively charged particles in an atom
k. periodic table
11. atoms of the same element that have different numbers of neutrons
l. atom
12. number of protons in an atom’s nucleus
m. atomic mass unit
13. horizontal row in the periodic table
n. group
14. smallest known particle that makes up protons and neutrons
o. electron dot diagram
15. the smallest peice of matter that still retains the properties of the element
p. period
16. developed an early periodic chart 17. approximately 1.67 ✕ 10-24g
22 Properties of Atoms and the Periodic Table
q. Dmitri Mendeleev
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Meeting Individual Needs
2. region around the nucleus where the electrons are found
Column II
Name
Date
1
Reinforcement
Class
Structure of the Atom
Directions: Answer the following questions on the lines provided. 1. How is the chemical symbol of an element determined?
Meeting Individual Needs
2. What are atoms composed of?
3. Are electrons, protons, or neutrons the smallest particles? If not, what are?
4. How many types of quarks are there and what is the name of one of them?
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
5. Why do scientists use models to study atoms?
6. Why has the atomic model changed over time?
7. Why is the current atomic model called the “Electron Cloud Model”?
Directions: Match the term in Column I with the definition in Column II. Write the letter of the correct definition in the blank at the left. Column I
Column II
8. electron
a. positively charged particle
9. neutron
b. negatively charged particle
10. nucleus
c. neutral particle
11. proton
d. smaller particles that make up protons and neutrons e. positively charged center of an atom
12. quark
Properties of Atoms and the Periodic Table
27
Name
2
Date
Reinforcement
Class
Masses of Atoms
Directions: Answer the following questions on the lines provided. 1. What are isotopes?
3. What is the average atomic mass of an element?
4. Compare and contrast the atomic structure of the chlorine-35 and chlorine-37 isotopes.
5. Suppose that a newly discovered element called centium has three isotopes that occur in nature. These are centium-200, centium-203, and centium-209. Assume that these isotopes occur in equal amounts in nature. What will be the average atomic mass of this element?
28 Properties of Atoms and the Periodic Table
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Meeting Individual Needs
2. How do Boron-10 and Boron-11 differ?
Name
Date
3
Class
The Periodic Table
Reinforcement
Directions: You will need a scientist’s patience to find the names of the 70 elements hidden in the grid. The lanthanides and the actinides have been excluded. The same letters may appear in more than one element name. Draw a line through the letters that correctly spell the name of an element. A Y M R
A S
S M
R N U E
B L
U
G N T N
E
I
T T O
N C A D M A
I
I
L O
M
I
I
U M N
I
D N
J
E N
Z E
L
I
N E H L
H
G H P
B R O M
I
N E D A
P
L
N E H T U R C S
P
K L M U
Y O
P M Q R T S C M U V H E O H
I
Y D U
R X E U A S
C R N U R B D D
P E N
I
E
J
I
T
I
L
B L
F G O H O
I
H
U
P
R H
O R L
E M
O E N O D V P R D N
L Q T
K N D G A R T
N R
T H H
A A H
C N E D S T
U H Y A H E M P E R B E N
I
N
I
O B
I
I
U M O C
N E E
I
I
R U N T
I
D E
T
T
A T S A
A N A B E
L
E G O S C
I
S M U
I
N
I
T C A L
C
I
U M M U
I
I I
N
I
A
I
S
I
I
A
O G N L
F
F E A M L M T
S
L N D L
N O C R
I
Z
U U D N
I
A
E N
T T
L
I
I
A G H H
L
U
L
T P A S
I
M
V E R U E
E
O T U U H
I
E N
U
L
U N G C M N N R M Y M M R O R N T A H T U M S
I
B
O R M M M O U G M
L E
I
L D E U L M B O R O N M L E N N T S S
M N O B R A C M E S U L
U
L H
L
N U H T
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
L U O R
W S A Y X M D B Z K
S
F
D E
N O E O B O C
E
R G
I
I
T U E
I
D B
U P U T U N E T
E
I
A H E L R N
P
L
T
I
P E
I
U G M
I
L
I
R T T
Y N T
I
I
M N M
I
U U L M N
R
I
U M V
Y
I
F
I
A
I
U E M E C H R O M
I
U M A N
L
T S U O X Y G E N M
E E A V U E R M U
S E C M N B M K
T
I
I
R
C E M N M D E S E N A G N A M A M P
S
I
T R O N
D T
I
V
U M R A
E N
N E A D A N B E I
U A R
L A
O H T M A U D R M E
F D
C M U A M U
I
M S O L D
Directions: Complete the following paragraphs about the periodic table by filling each blank with the correct term. In the modern periodic table, elements are listed by increasing 1. ________________. Each box represents an 2. ________________. A box contains the name, atomic number, 3. ________________, and 4. ________________ for the element. Vertical columns in the table are called 5. ________________. Most elements in a column have the same number of 6. ________________ in the outer energy level and tend to have similar 7._________________. Horizontal rows in the table are called 8. ________________. The elements on the left side of the table are 9. ________________. Groups 3–12 contain metals known as 10. ________________. Elements on the right side are 11. ________________.
Properties of Atoms and the Periodic Table
29
Meeting Individual Needs
O O S
I
Name
1
Date
Enrichment
Class
The Building Blocks of Matter
From experiments involving the high-speed collision of particles, scientists have determined that heavy nuclear particles, such as protons and neutrons, are composed of quarks. The name “quark” was taken from a novel. Quarks are classified into six flavors—up, down, strange, charm, bottom, and top. The flavors are not related to any physical characteristics of the quarks themselves, but are used as classifications. Unlike protons and electrons, which carry whole charges of +1 or –1, quarks carry fractional charges. The following table lists some information about quarks.
Quarks Symbol
Charge
Name
Symbol
Charge
up
u
2/3
down
d
1/3
strange
s
1/3
charm
c
2/3
bottom
b
1/3
top
t
2/3
Mass
1. Use the library to find the name of the author and novel from which the word “quark” was taken. 2. Use the library to draw a time line showing the history of quarks.
3. Protons and neutrons are composed of triplets of up and down quarks. Use the information in the table to determine which of the following quark triplets represents a proton and which represents a neutron. udd __________________
uud __________________
4. A heavier nuclear particle is composed of a triplet of strange quarks. What is the charge of this particle?
30 Properties of Atoms and the Periodic Table
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Meeting Individual Needs
Name
Name
Enrichment
Class
The Mole
You have learned that the mass of atoms is measured in atomic mass units. This unit is too small to use in everyday measurement. It would be simpler to have a number of atoms that would have a mass in grams that is equal to the mass of one atom in atomic mass units. The same number would fit all elements, because equal numbers of different atoms always have the same mass ratio. Chemists have found that 6.02 ✕ 1023 atoms of an element have a mass in grams equivalent to the mass of one atom in atomic mass units. This counting unit is called a mole. For example, one mole of helium atoms has a mass of 4 grams because helium has a mass number of 4. Do you know how big a number a mole is? Suppose the entire population of the world, more than four billion people, were assigned to count the number of atoms in one mole of helium. If each person counted one atom per second and worked a 48-hour work week, the task would take more than 10 million years. If you had one mole of pennies, you would have enough money to pay all the expenses of the United States for the next billion years. 1. A mole is a certain number of items. What number does each of the following terms represent? a. dozen ______________
d. mole ______________
b. billion ______________
e. gross ______________
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
c. million ______________ 2. Using a laboratory balance, measure and record the mass of one mole of each of the following elements: carbon, iron nails, zinc metal, and copper wire.
3. Find the mass, in grams, of each of the following: a. 2 moles of aluminum ______________ b. 4 moles of magnesium ______________ c. 3 moles of helium ______________ 4. How many moles are in each of the following: a. 156 grams of chromium ______________ b. 156 grams of potassium ______________ c. 119 grams of uranium ______________ 5. Why is the counting unit called a mole useful for chemists?
Properties of Atoms and the Periodic Table
31
Meeting Individual Needs
2
Date
Name
3
Date
Enrichment
Class
Predicting an Element’s Group and Period
Several scientists, including Newlands, Meyer, and Mendeleev worked on classification systems that grouped elements according to their properties. They found that these properties repeated in a regular or periodic manner. This fact was used to predict properties of undiscovered elements. Review electron arrangement from your textbook. In Table 1, write the maximum number of electrons that can fill each energy level on the blanks in the table heading. Write the total number of electrons for each element in the first column labeled Total. For each element, assign the correct number of electrons to each energy level. Complete Table 2 by using the information from the six elements studied.
Electrons Element Total
Level 1
Level 2
Level 3
Number of outer electrons
Located in group
1. Argon 2. Carbon 3. Helium 4. Lithium 5. Silicon 6. Sodium
Table 2 Element
Energy level of outer electrons
Located in period
7. Ar 8. C 9. He 10. Li 11. Si 12. Na
13. How is the element’s period related to the number of energy levels over which its electrons are spread? 14. How can you predict an element’s group and period?
32 Properties of Atoms and the Periodic Table
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Meeting Individual Needs
Table 1
Name
Date
Note-taking Worksheet Section 1
Class
Properties of Atoms and the Periodic Table
Structure of the Atom
A. ____________ are abbreviated in scientific shorthand—first letter or two of element’s name B. ________—smallest piece of matter that still has the properties of the element 1. ___________ have electrical charge of 1+.
3. _____________ have electrical charge of 1-. 4. Protons and neutrons are in the ___________ of an atom; electrons surround the nucleus. C. Protons and neutrons are made up of smaller particles called __________. 1. Six quarks are known to exist; the sixth is called the _______ quark. D. Scientists use scaled-up __________ to represent atoms. 1. Early models of atoms used a solid __________. 2. Current __________________ model shows electrons traveling in specific energy levels around a nucleus of protons and neutrons.
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Section 2
Masses of Atoms
A. _______________—composed mostly of the protons and neutrons in the nucleus 1. Unit of measurement for atomic particles is ____________________ (amu) which is one-twelfth the mass of a carbon atom containing six protons and six neutrons. 2. _________________—the number of protons in an atom; number of protons also identifies the element 3. The sum of the number of protons and neutrons in the nucleus of an atom is the _______________. B. ____________—atoms of the same element with different numbers of neutrons 1. Different isotopes have different ______________. 2. Number of ____________ is equal to mass number minus atomic number. 3. Name of ___________ followed by mass number identifies the isotope. 4. _______________________ is the weighted-average mass of an element’s isotopes. 5. Average atomic mass is closest to its most ____________ isotope.
Properties of Atoms and the Periodic Table
33
Meeting Individual Needs
2. ____________ do not have an electrical charge.
Name
Date
Class
Note-taking Worksheet (continued) Section 3
The Periodic Table
A. Elements are organized in the __________________ by increasing atomic number. 1. In the late 1800’s, Dmitri Medeleev devised the first periodic table based on _______________. 2. In 1913, Henry G. J. Moseley arranged the elements by _________________ rather than atomic mass. B. Vertical columns in the periodic table are __________ of elements with similar properties.
2. Each of the seven energy levels can have a ___________ number of electrons. a. Energy level one can contain at most _______ electrons. b. Energy level two can contain at most _________ electrons. 3. Each row in the periodic table ends when an outer energy level is __________. 4. _________________________ use the element symbol and dots to represent outer energy level electrons. C. ___________—horizontal rows of elements that contain increasing numbers of protons and electrons. 1. Elements are ______________ as metals, nonmetals, or metalloids (semimetals). 2. Elements are _______________ in laboratories all over the world. D. The ________ elements exist all over the universe. 1. Hydrogen and helium are the ___________________ of other naturally occurring elements. 2. ______________ spread heavier elements throughout the universe.
34 Properties of Atoms and the Periodic Table
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Meeting Individual Needs
1. Elements in the same group have the same number of _____________ in their outer energy level.
Name
Date
Class
Properties of Atoms and the Periodic Table
Chapter Review Part A. Vocabulary Review
Directions: On the space at the left, write the term that correctly completes each statement. Use each term once. metals groups electrons chemical symbol
isotopes metalloids nucleus
average atomic mass electron cloud transition elements atomic number mass number periods quarks periodic table
1. A capital letter or a combination of a capital letter and a small letter that is used to represent an element is called a(n) ______. 2. The horizontal rows of elements are called ______. 3. An average of the masses of all the isotopes that occur in nature for an element is the ______. 4. Vertical columns of elements are called ______. 5. Elements in the middle of the periodic table, groups 4 through 7, are called the ______.
7. Protons and neutrons can be subdivided into ______ by colliding them. 8. The center of an atom where protons and neutrons are located is the ______. 9. A total count of the neutrons and protons in an atom is the ______. 10. Atoms of the same element but with different numbers of neutrons are ______. 11. Elements that are found on the left side of the periodic table are ______. 12. Elements that have some properties of both metals and nonmetals are ______. 13. The particles that move about the nucleus and have a negative charge are ______. 14. The region around the nucleus occupied by electrons is a(n) ______. 15. A chart that shows the classification of elements is called the ______.
Properties of Atoms and the Periodic Table
37
Assessment
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
6. The number of protons in an atom is the ______.
Name
Date
Class
Chapter Review (continued) Part B. Concept Review Directions: Complete the table below by writing the correct information in the blank spaces. Chemical symbol
Element
Atomic number
Number of protons
Number of neutrons
Mass number
11
11
12
23
6
6
12
26
30
56
16
32
1. Sodium 2. Carbon
C
3.
Fe
26
4. Sulfur
S
16
5. Nitrogen
N
7
7
6. Oxygen
O
8
8
8
7.
He
2
2
2
8. Chlorine-35
Cl
17
17
9. Copper
Cu
29
29
35
17
20
Cl
10. Chlorine-37
14
4 35
37
1
18
11
Assessment
Na 2
13
14
15
16
17
23
26
3
A
4
5
6
7
8
9
10
11
12
C
Fe
Fe 55.8
79
Au 197
Au B
11. Which element has a greater atomic mass, A or B? 12. Which element is a metal, B or C? 13. In which group is gold? 14. What is the average atomic mass of iron? 15. What is the atomic number of sodium? 38 Properties of Atoms and the Periodic Table
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Directions: Refer to the periodic table below and the boxes at the right of the table to answer questions 11–15.
Name
1
Date
Section Focus Transparency Activity
Class
Subatomic Collision
Transparency Activities
1. Why do you think scientists have only recently discovered these subatomic particles? 2. What might scientists learn by breaking apart atomic nuclei?
44 Properties of Atoms and the Periodic Table
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An individual atom is so small that it would take 50 million of them lined up in a row to equal one centimeter! Atoms, however, can be divided into component parts, and, amazingly, some of these parts have particles that are tinier yet. Below is an image created by these subatomic particles taken in a device called a bubble chamber.
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Carbon Cat
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How old are these mummified cats found in an Egyptian tomb? Carbon-14 holds the answer. Carbon-14 is a radioactive form of carbon, an element found in every living thing. By measuring how much carbon-14 remains in these cats, scientists can tell approximately how many years ago the cats were buried.
1. Carbon-14 decays over time. What does “decay” mean? 2. Why do you think carbon is used by scientists to date objects such as mummies, bones, and cloth wrappings? 3. Is it possible to use carbon-14 dating on things that were never alive? Why or why not? Properties of Atoms and the Periodic Table
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What makes the glass glow?
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2. Why do you think the glass glows? 3. Why might prolonged work with such glass be dangerous?
46 Properties of Atoms and the Periodic Table
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
When you hear the word uranium, you might think of nuclear power. Uranium, though, was used in the 19th century by European glassmakers to create what was called uranium glass. This interesting glass had a yellowish-green color and glows under certain lighting conditions.
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Electron Cloud Model
Nucleus
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Electron cloud
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(continued)
1. What is the region around the nucleus called? 2. What was the name of the Greek who proposed the idea that atoms made up all substances? 3. What is an electron cloud?
4. What determines how far each electron travels from the nucleus? 5. Why can’t electron positions be pinpointed?
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6. Electrons are located in a cloud surrounding what part of the atom?
48 Properties of Atoms and the Periodic Table
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Properties of Atoms and the Periodic Table
Directions: Carefully review the table and answer the following questions. Characteristics of Some Alkaline Earth Metals Atomic number
Mass number
Melting point (˚C)
Boiling point (˚C)
Magnesium
12
24
651
1105
Calcium
20
40
842
1494
Strontium
38
88
769
1384
Barium
56
137
725
1640
1. According to the table, which alkaline Earth metal has a mass number greater than 100? A Magnesium C Strontium B Calcium D Barium 2. According to the table, which element has the LOWEST atomic number? F Magnesium H Strontium G Calcium J Barium 3. According to the table, which element has the HIGHEST melting point? A Magnesium C Strontium B Calcium D Barium
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Element
4. The number of neutrons in the nucleus of an atom is equal to the mass number minus the atomic number. According to this definition and the table, how many neutrons are in the nucleus of a strontium atom? F 20 G 38 H 50 J 81 Properties of Atoms and the Periodic Table
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