Atoms, Elements, Isotopes
Presentation
•
Science
•
9th - 12th Grade
•
Practice Problem
•
Hard
Priya Verma
FREE Resource
156 Slides • 2 Questions
1
LecturePLUS Timberlake
1
The Atom
Atomic Number and Mass
Number
Isotopes
2
LecturePLUS Timberlake
2
Atomic Theory
Atoms are building blocks of elements
Similar atoms in each element.
Different from atoms of other elements.
Two or more different atoms bond in simple
ratios to form compounds.
3
Fill in the Blank
____are building blocks of elements.
4
Match
Match the following
Similar atoms in
Two or more different atoms bond in
Group of atoms
Elements
Compounds
Molecules
Elements
Compounds
Molecules
5
LecturePLUS Timberlake
3
Subatomic Particles
Particle
Symbol
Charge
Relative
Mass
Electron
e-
1-
0
Proton p+
+
1
Neutron
n
0
1
6
LecturePLUS Timberlake
4
Location of Subatomic Particles
10-13 cm
electrons
protons
neutrons
10-8 cm
nucleus
7
LecturePLUS Timberlake
5
Atomic Number
Counts the number
of
protons
in an atom
8
LecturePLUS Timberlake
6
Periodic Table
Represents physical and chemical
behavior of elements
Arranges elements by increasing atomic
number
Repeats similar properties in columns
known as chemical families or groups
9
LecturePLUS Timberlake
7
Periodic Table
1
2
3 4 5 6 7
8
11
Na
10
LecturePLUS Timberlake
8
Atomic Number on the Periodic
Table
11
Na
Atomic Number
Symbol
11
LecturePLUS Timberlake
9
All atoms of an element have
the same number of protons
11
Na
11 protons
Sodium
12
LecturePLUS Timberlake
10
Learning Check AT 1
State the number of protons for atoms of each
of the following:
A. Nitrogen
1) 5 protons
2) 7 protons 3) 14
protons
B. Sulfur
1) 32 protons
2) 16 protons 3) 6 protons
C. Barium
1) 137 protons 2) 81 protons 3) 56 protons
13
LecturePLUS Timberlake
11
Solution AT 1
State the number of protons for atoms of each
of the following:
A. Nitrogen
2) 7 protons
B. Sulfur
2) 16 protons
C. Barium
3) 56 protons
14
LecturePLUS Timberlake
12
Number of Electrons
An atom is neutral
The net charge is zero
Number of protons = Number of electrons
Atomic number = Number of electrons
15
LecturePLUS Timberlake
13
Mass Number
Counts the number
of
protons and neutrons
in an atom
16
LecturePLUS Timberlake
14
Atomic Symbols
Show the mass number and atomic number
Give the symbol of the element
mass number
23 Na
sodium-23
atomic number11
17
LecturePLUS Timberlake
15
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
8 p+
15 p+
30 p+
8 n
16 n
35 n
8 e-
15e-
30 e-
18
LecturePLUS Timberlake
16
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
19
LecturePLUS Timberlake
17
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
8 p+
15 p+
30 p+
8 n
16 n
35 n
8 e-
15e-
30 e-
20
LecturePLUS Timberlake
18
Isotopes
Atoms with the same number of protons,
but different numbers of neutrons.
Atoms of the same element (same atomic
number) with different mass numbers
Isotopes of chlorine
35Cl
37Cl
17
17
chlorine - 35 chlorine - 37
21
LecturePLUS Timberlake
19
Learning Check AT 2
Naturally occurring carbon consists of three
isotopes, 12C, 13C, and 14C. State the number of
protons, neutrons, and electrons in each of
these carbon atoms.
12C
13C
14C
6
6
6
#P _______ _______ _______
#N _______ _______ _______
#E _______ _______ _______
22
LecturePLUS Timberlake
20
Solution AT 2
12C
13C
14C
6
6
6
#P __6___ _ 6___ ___6___
#N __6___ _ _7___ ___8___
#E __6___ _ 6___ ___6___
23
LecturePLUS Timberlake
21
Learning Check AT 3
An atom of zinc has a mass number of 65.
A.
Number of protons in the zinc atom
1) 30
2) 35
3) 65
B.
Number of neutrons in the zinc atom
1) 30
2) 35
3) 65
C. What is the mass number of a zinc isotope
with 37 neutrons?
1) 37
2) 65
3) 67
24
LecturePLUS Timberlake
22
Solution AT 3
An atom of zinc has a mass number of 65.
A.
Number of protons in the zinc atom
1) 30
B.
Number of neutrons in the zinc atom
2) 35
C. What is the mass number of a zinc isotope
with 37 neutrons?
3) 67
25
LecturePLUS Timberlake
23
Learning Check AT 4
Write the atomic symbols for atoms with the following:
A. 8 p+, 8 n, 8 e-
___________
B.
17p+, 20n, 17e-___________
C. 47p+, 60 n, 47 e-___________
26
LecturePLUS Timberlake
24
Solution AT 4
16O
A. 8 p+, 8 n, 8 e-
8
B.
17p+, 20n, 17e-37Cl
17
C. 47p+, 60 n, 47 e-107Ag
47
27
LecturePLUS Timberlake
25
Learning Check AT 5
An atom has 14 protons and 20 neutrons.
A.
Its atomic number is
1) 14
2) 16
3) 34
B. Its mass number is
1) 14
2) 16
3) 34
C. The element is
1) Si
2) Ca
3) Se
D.
Another isotope of this element is
1)34X
2)34X
3)36X
16
14 14
28
LecturePLUS Timberlake
26
Solution AT 5
An atom has 14 protons and 20 neutrons.
A.
It has atomic number
1) 14
B. It has a mass number of
3) 34
C. The element is
1) Si
D.
Another isotope of this element would be
3) 36X
14
29
LecturePLUS Timberlake
27
Masses of Atoms
A scale designed for atoms gives their small
atomic masses in atomic mass units (amu)
An atom of 12C was assigned an exact mass of
12.00 amu
Relative masses of all other atoms was
determined by comparing each to the mass of
12C
An atom twice as heavy has a mass of 24.00
amu. An atom half as heavy is 6.00 amu.
30
LecturePLUS Timberlake
28
Atomic Mass
Listed on the periodic table
Gives the mass of “average” atom of each
element compared to 12C
Average atom based on all the isotopes and their
abundance %
Atomic mass is not a whole number
Na
22.99
31
LecturePLUS Timberlake
29
Learning Check AT6
Using the periodic table, specify the atomic
mass of each element (round to the tenths
place):
A.
calcium
__________
B. aluminum
__________
C.
lead __________
D. barium __________
E. iron
__________
32
LecturePLUS Timberlake
30
Solution AT6
Using the periodic table, specify the atomic
mass of each element (round to the tenths
place):
A.
calcium
_40.1 amu _
B. aluminum
_27.0 amu _
C.
lead _207.2 amu_
D. barium _137.3 amu_
E. iron
_55.8 amu__
33
LecturePLUS Timberlake
31
Calculating Atomic Mass
Percent(%) abundance of isotopes
Mass of each isotope of that element
Weighted average =
mass isotope1(%) + mass isotope2(%) + …
100
100
34
LecturePLUS Timberlake
32
Atomic Mass of Magnesium
Isotopes Mass of Isotope Abundance
24Mg
=
24.0 amu
78.70%
25Mg
=
25.0 amu
10.13%
26Mg
= 26.0 amu
11.17%
Atomic mass (average mass) Mg = 24.3 amu
Mg
24.3
35
LecturePLUS Timberlake
33
Learning Check AT7
Gallium is a metallic element found in
small lasers used in compact disc players.
In a sample of gallium, there is 60.2% of
gallium-69 (68.9 amu) atoms and 39.8% of
gallium-71 (70.9 amu) atoms. What is the
atomic mass of gallium?
36
LecturePLUS Timberlake
34
Solution AT7
Ga-69
68.9 amu x 60.2 = 41.5 amu for 69Ga
100
Ga-71 (%/100)
70.9 amu x 39.8
=
28.2 amu for 71Ga
100
Atomic mass Ga
=
69.7 amu
37
LecturePLUS Timberlake
35
Finding An Isotopic Mass
A sample of boron consists of 10B (mass
10.0 amu) and 11B (mass 11.0 amu). If
the average atomic mass of B is 10.8
amu, what is the % abundance of each
boron isotope?
38
LecturePLUS Timberlake
36
Assign X and Y values:
X = % 10B Y = % 11B
Determine Y in terms of X
X + Y = 100
Y = 100 - X
Solve for X:
X (10.0) + (100 - X )(11.0) = 10.8
100 100
Multiply through by 100
10.0 X + 1100 - 11.0X = 1080
39
LecturePLUS Timberlake
37
Collect X terms
10.0 X - 11.0 X = 1080 - 1100
- 1.0 X = -20
X = -20 = 20 % 10B
- 1.0
Y = 100 - X
% 11B = 100 - 20% = 80% 11B
40
LecturePLUS Timberlake
38
Learning Check AT8
Copper has two isotopes 63Cu (62.9
amu) and 65Cu (64.9 amu). What is the %
abundance of each isotope? (Hint:
Check periodic table for atomic mass)
1) 30%
2) 70%
3) 100%
41
LecturePLUS Timberlake
39
Solution AT8
2) 70%
Solution
62.9X + 6490 = 64.9X = 6350
-2.0 X = -140
X = 70%
42
LecturePLUS Timberlake
1
The Atom
Atomic Number and Mass
Number
Isotopes
43
LecturePLUS Timberlake
1
The Atom
Atomic Number and Mass
Number
Isotopes
44
LecturePLUS Timberlake
2
Atomic Theory
Atoms are building blocks of elements
Similar atoms in each element
Different from atoms of other elements
Two or more different atoms bond in simple
ratios to form compounds
45
LecturePLUS Timberlake
3
Subatomic Particles
Particle
Symbol
Charge
Relative
Mass
Electron
e-
1-
0
Proton p+
+
1
Neutron
n
0
1
46
LecturePLUS Timberlake
4
Location of Subatomic Particles
10-13 cm
electrons
protons
neutrons
10-8 cm
nucleus
47
LecturePLUS Timberlake
5
Atomic Number
Counts the number
of
protons
in an atom
48
LecturePLUS Timberlake
6
Periodic Table
Represents physical and chemical
behavior of elements
Arranges elements by increasing atomic
number
Repeats similar properties in columns
known as chemical families or groups
49
LecturePLUS Timberlake
7
Periodic Table
1
2
3 4 5 6 7
8
11
Na
50
LecturePLUS Timberlake
8
Atomic Number on the Periodic
Table
11
Na
Atomic Number
Symbol
51
LecturePLUS Timberlake
9
All atoms of an element have
the same number of protons
11
Na
11 protons
Sodium
52
LecturePLUS Timberlake
10
Learning Check AT 1
State the number of protons for atoms of each
of the following:
A. Nitrogen
1) 5 protons
2) 7 protons 3) 14
protons
B. Sulfur
1) 32 protons
2) 16 protons 3) 6 protons
C. Barium
1) 137 protons 2) 81 protons 3) 56 protons
53
LecturePLUS Timberlake
11
Solution AT 1
State the number of protons for atoms of each
of the following:
A. Nitrogen
2) 7 protons
B. Sulfur
2) 16 protons
C. Barium
3) 56 protons
54
LecturePLUS Timberlake
12
Number of Electrons
An atom is neutral
The net charge is zero
Number of protons = Number of electrons
Atomic number = Number of electrons
55
LecturePLUS Timberlake
13
Mass Number
Counts the number
of
protons and neutrons
in an atom
56
LecturePLUS Timberlake
14
Atomic Symbols
Show the mass number and atomic number
Give the symbol of the element
mass number
23 Na
sodium-23
atomic number11
57
LecturePLUS Timberlake
15
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
8 p+
15 p+
30 p+
8 n
16 n
35 n
8 e-
15e-
30 e-
58
LecturePLUS Timberlake
16
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
59
LecturePLUS Timberlake
17
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
8 p+
15 p+
30 p+
8 n
16 n
35 n
8 e-
15e-
30 e-
60
LecturePLUS Timberlake
18
Isotopes
Atoms with the same number of protons,
but different numbers of neutrons.
Atoms of the same element (same atomic
number) with different mass numbers
Isotopes of chlorine
35Cl
37Cl
17
17
chlorine - 35 chlorine - 37
61
LecturePLUS Timberlake
19
Learning Check AT 2
Naturally occurring carbon consists of three
isotopes, 12C, 13C, and 14C. State the number of
protons, neutrons, and electrons in each of
these carbon atoms.
12C
13C
14C
6
6
6
#P _______ _______ _______
#N _______ _______ _______
#E _______ _______ _______
62
LecturePLUS Timberlake
20
Solution AT 2
12C
13C
14C
6
6
6
#P __6___ _ 6___ ___6___
#N __6___ _ _7___ ___8___
#E __6___ _ 6___ ___6___
63
LecturePLUS Timberlake
21
Learning Check AT 3
An atom of zinc has a mass number of 65.
A.
Number of protons in the zinc atom
1) 30
2) 35
3) 65
B.
Number of neutrons in the zinc atom
1) 30
2) 35
3) 65
C. What is the mass number of a zinc isotope
with 37 neutrons?
1) 37
2) 65
3) 67
64
LecturePLUS Timberlake
22
Solution AT 3
An atom of zinc has a mass number of 65.
A.
Number of protons in the zinc atom
1) 30
B.
Number of neutrons in the zinc atom
2) 35
C. What is the mass number of a zinc isotope
with 37 neutrons?
3) 67
65
LecturePLUS Timberlake
23
Learning Check AT 4
Write the atomic symbols for atoms with the following:
A. 8 p+, 8 n, 8 e-
___________
B.
17p+, 20n, 17e-___________
C. 47p+, 60 n, 47 e-___________
66
LecturePLUS Timberlake
24
Solution AT 4
16O
A. 8 p+, 8 n, 8 e-
8
B.
17p+, 20n, 17e-37Cl
17
C. 47p+, 60 n, 47 e-107Ag
47
67
LecturePLUS Timberlake
25
Learning Check AT 5
An atom has 14 protons and 20 neutrons.
A.
Its atomic number is
1) 14
2) 16
3) 34
B. Its mass number is
1) 14
2) 16
3) 34
C. The element is
1) Si
2) Ca
3) Se
D.
Another isotope of this element is
1)34X
2)34X
3)36X
16
14 14
68
LecturePLUS Timberlake
26
Solution AT 5
An atom has 14 protons and 20 neutrons.
A.
It has atomic number
1) 14
B. It has a mass number of
3) 34
C. The element is
1) Si
D.
Another isotope of this element would be
3) 36X
14
69
LecturePLUS Timberlake
27
Masses of Atoms
A scale designed for atoms gives their small
atomic masses in atomic mass units (amu)
An atom of 12C was assigned an exact mass of
12.00 amu
Relative masses of all other atoms was
determined by comparing each to the mass of
12C
An atom twice as heavy has a mass of 24.00
amu. An atom half as heavy is 6.00 amu.
70
LecturePLUS Timberlake
28
Atomic Mass
Listed on the periodic table
Gives the mass of “average” atom of each
element compared to 12C
Average atom based on all the isotopes and their
abundance %
Atomic mass is not a whole number
Na
22.99
71
LecturePLUS Timberlake
29
Learning Check AT6
Using the periodic table, specify the atomic
mass of each element (round to the tenths
place):
A.
calcium
__________
B. aluminum
__________
C.
lead __________
D. barium __________
E. iron
__________
72
LecturePLUS Timberlake
30
Solution AT6
Using the periodic table, specify the atomic
mass of each element (round to the tenths
place):
A.
calcium
_40.1 amu _
B. aluminum
_27.0 amu _
C.
lead _207.2 amu_
D. barium _137.3 amu_
E. iron
_55.8 amu__
73
LecturePLUS Timberlake
31
Calculating Atomic Mass
Percent(%) abundance of isotopes
Mass of each isotope of that element
Weighted average =
mass isotope1(%) + mass isotope2(%) + …
100
100
74
LecturePLUS Timberlake
32
Atomic Mass of Magnesium
Isotopes Mass of Isotope Abundance
24Mg
=
24.0 amu
78.70%
25Mg
=
25.0 amu
10.13%
26Mg
= 26.0 amu
11.17%
Atomic mass (average mass) Mg = 24.3 amu
Mg
24.3
75
LecturePLUS Timberlake
33
Learning Check AT7
Gallium is a metallic element found in
small lasers used in compact disc players.
In a sample of gallium, there is 60.2% of
gallium-69 (68.9 amu) atoms and 39.8% of
gallium-71 (70.9 amu) atoms. What is the
atomic mass of gallium?
76
LecturePLUS Timberlake
34
Solution AT7
Ga-69
68.9 amu x 60.2 = 41.5 amu for 69Ga
100
Ga-71 (%/100)
70.9 amu x 39.8
=
28.2 amu for 71Ga
100
Atomic mass Ga
=
69.7 amu
77
LecturePLUS Timberlake
35
Finding An Isotopic Mass
A sample of boron consists of 10B (mass
10.0 amu) and 11B (mass 11.0 amu). If
the average atomic mass of B is 10.8
amu, what is the % abundance of each
boron isotope?
78
LecturePLUS Timberlake
36
Assign X and Y values:
X = % 10B Y = % 11B
Determine Y in terms of X
X + Y = 100
Y = 100 - X
Solve for X:
X (10.0) + (100 - X )(11.0) = 10.8
100 100
Multiply through by 100
10.0 X + 1100 - 11.0X = 1080
79
LecturePLUS Timberlake
37
Collect X terms
10.0 X - 11.0 X = 1080 - 1100
- 1.0 X = -20
X = -20 = 20 % 10B
- 1.0
Y = 100 - X
% 11B = 100 - 20% = 80% 11B
80
LecturePLUS Timberlake
38
Learning Check AT8
Copper has two isotopes 63Cu (62.9
amu) and 65Cu (64.9 amu). What is the %
abundance of each isotope? (Hint:
Check periodic table for atomic mass)
1) 30%
2) 70%
3) 100%
81
LecturePLUS Timberlake
39
Solution AT8
2) 70%
Solution
62.9X + 6490 = 64.9X = 6350
-2.0 X = -140
X = 70%
82
LecturePLUS Timberlake
2
Atomic Theory
Atoms are building blocks of elements
Similar atoms in each element
Different from atoms of other elements
Two or more different atoms bond in simple
ratios to form compounds
83
LecturePLUS Timberlake
3
Subatomic Particles
Particle
Symbol
Charge
Relative
Mass
Electron
e-
1-
0
Proton p+
+
1
Neutron
n
0
1
84
LecturePLUS Timberlake
4
Location of Subatomic Particles
10-13 cm
electrons
protons
neutrons
10-8 cm
nucleus
85
LecturePLUS Timberlake
5
Atomic Number
Counts the number
of
protons
in an atom
86
LecturePLUS Timberlake
6
Periodic Table
Represents physical and chemical
behavior of elements
Arranges elements by increasing atomic
number
Repeats similar properties in columns
known as chemical families or groups
87
LecturePLUS Timberlake
7
Periodic Table
1
2
3 4 5 6 7
8
11
Na
88
LecturePLUS Timberlake
8
Atomic Number on the Periodic
Table
11
Na
Atomic Number
Symbol
89
LecturePLUS Timberlake
9
All atoms of an element have
the same number of protons
11
Na
11 protons
Sodium
90
LecturePLUS Timberlake
10
Learning Check AT 1
State the number of protons for atoms of each
of the following:
A. Nitrogen
1) 5 protons
2) 7 protons 3) 14
protons
B. Sulfur
1) 32 protons
2) 16 protons 3) 6 protons
C. Barium
1) 137 protons 2) 81 protons 3) 56 protons
91
LecturePLUS Timberlake
11
Solution AT 1
State the number of protons for atoms of each
of the following:
A. Nitrogen
2) 7 protons
B. Sulfur
2) 16 protons
C. Barium
3) 56 protons
92
LecturePLUS Timberlake
12
Number of Electrons
An atom is neutral
The net charge is zero
Number of protons = Number of electrons
Atomic number = Number of electrons
93
LecturePLUS Timberlake
13
Mass Number
Counts the number
of
protons and neutrons
in an atom
94
LecturePLUS Timberlake
14
Atomic Symbols
Show the mass number and atomic number
Give the symbol of the element
mass number
23 Na
sodium-23
atomic number11
95
LecturePLUS Timberlake
15
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
8 p+
15 p+
30 p+
8 n
16 n
35 n
8 e-
15e-
30 e-
96
LecturePLUS Timberlake
16
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
97
LecturePLUS Timberlake
17
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
8 p+
15 p+
30 p+
8 n
16 n
35 n
8 e-
15e-
30 e-
98
LecturePLUS Timberlake
18
Isotopes
Atoms with the same number of protons,
but different numbers of neutrons.
Atoms of the same element (same atomic
number) with different mass numbers
Isotopes of chlorine
35Cl
37Cl
17
17
chlorine - 35 chlorine - 37
99
LecturePLUS Timberlake
19
Learning Check AT 2
Naturally occurring carbon consists of three
isotopes, 12C, 13C, and 14C. State the number of
protons, neutrons, and electrons in each of
these carbon atoms.
12C
13C
14C
6
6
6
#P _______ _______ _______
#N _______ _______ _______
#E _______ _______ _______
100
LecturePLUS Timberlake
20
Solution AT 2
12C
13C
14C
6
6
6
#P __6___ _ 6___ ___6___
#N __6___ _ _7___ ___8___
#E __6___ _ 6___ ___6___
101
LecturePLUS Timberlake
21
Learning Check AT 3
An atom of zinc has a mass number of 65.
A.
Number of protons in the zinc atom
1) 30
2) 35
3) 65
B.
Number of neutrons in the zinc atom
1) 30
2) 35
3) 65
C. What is the mass number of a zinc isotope
with 37 neutrons?
1) 37
2) 65
3) 67
102
LecturePLUS Timberlake
22
Solution AT 3
An atom of zinc has a mass number of 65.
A.
Number of protons in the zinc atom
1) 30
B.
Number of neutrons in the zinc atom
2) 35
C. What is the mass number of a zinc isotope
with 37 neutrons?
3) 67
103
LecturePLUS Timberlake
23
Learning Check AT 4
Write the atomic symbols for atoms with the following:
A. 8 p+, 8 n, 8 e-
___________
B.
17p+, 20n, 17e-___________
C. 47p+, 60 n, 47 e-___________
104
LecturePLUS Timberlake
24
Solution AT 4
16O
A. 8 p+, 8 n, 8 e-
8
B.
17p+, 20n, 17e-37Cl
17
C. 47p+, 60 n, 47 e-107Ag
47
105
LecturePLUS Timberlake
25
Learning Check AT 5
An atom has 14 protons and 20 neutrons.
A.
Its atomic number is
1) 14
2) 16
3) 34
B. Its mass number is
1) 14
2) 16
3) 34
C. The element is
1) Si
2) Ca
3) Se
D.
Another isotope of this element is
1)34X
2)34X
3)36X
16
14 14
106
LecturePLUS Timberlake
26
Solution AT 5
An atom has 14 protons and 20 neutrons.
A.
It has atomic number
1) 14
B. It has a mass number of
3) 34
C. The element is
1) Si
D.
Another isotope of this element would be
3) 36X
14
107
LecturePLUS Timberlake
27
Masses of Atoms
A scale designed for atoms gives their small
atomic masses in atomic mass units (amu)
An atom of 12C was assigned an exact mass of
12.00 amu
Relative masses of all other atoms was
determined by comparing each to the mass of
12C
An atom twice as heavy has a mass of 24.00
amu. An atom half as heavy is 6.00 amu.
108
LecturePLUS Timberlake
28
Atomic Mass
Listed on the periodic table
Gives the mass of “average” atom of each
element compared to 12C
Average atom based on all the isotopes and their
abundance %
Atomic mass is not a whole number
Na
22.99
109
LecturePLUS Timberlake
29
Learning Check AT6
Using the periodic table, specify the atomic
mass of each element (round to the tenths
place):
A.
calcium
__________
B. aluminum
__________
C.
lead __________
D. barium __________
E. iron
__________
110
LecturePLUS Timberlake
30
Solution AT6
Using the periodic table, specify the atomic
mass of each element (round to the tenths
place):
A.
calcium
_40.1 amu _
B. aluminum
_27.0 amu _
C.
lead _207.2 amu_
D. barium _137.3 amu_
E. iron
_55.8 amu__
111
LecturePLUS Timberlake
31
Calculating Atomic Mass
Percent(%) abundance of isotopes
Mass of each isotope of that element
Weighted average =
mass isotope1(%) + mass isotope2(%) + …
100
100
112
LecturePLUS Timberlake
32
Atomic Mass of Magnesium
Isotopes Mass of Isotope Abundance
24Mg
=
24.0 amu
78.70%
25Mg
=
25.0 amu
10.13%
26Mg
= 26.0 amu
11.17%
Atomic mass (average mass) Mg = 24.3 amu
Mg
24.3
113
LecturePLUS Timberlake
33
Learning Check AT7
Gallium is a metallic element found in
small lasers used in compact disc players.
In a sample of gallium, there is 60.2% of
gallium-69 (68.9 amu) atoms and 39.8% of
gallium-71 (70.9 amu) atoms. What is the
atomic mass of gallium?
114
LecturePLUS Timberlake
34
Solution AT7
Ga-69
68.9 amu x 60.2 = 41.5 amu for 69Ga
100
Ga-71 (%/100)
70.9 amu x 39.8
=
28.2 amu for 71Ga
100
Atomic mass Ga
=
69.7 amu
115
LecturePLUS Timberlake
35
Finding An Isotopic Mass
A sample of boron consists of 10B (mass
10.0 amu) and 11B (mass 11.0 amu). If
the average atomic mass of B is 10.8
amu, what is the % abundance of each
boron isotope?
116
LecturePLUS Timberlake
36
Assign X and Y values:
X = % 10B Y = % 11B
Determine Y in terms of X
X + Y = 100
Y = 100 - X
Solve for X:
X (10.0) + (100 - X )(11.0) = 10.8
100 100
Multiply through by 100
10.0 X + 1100 - 11.0X = 1080
117
LecturePLUS Timberlake
37
Collect X terms
10.0 X - 11.0 X = 1080 - 1100
- 1.0 X = -20
X = -20 = 20 % 10B
- 1.0
Y = 100 - X
% 11B = 100 - 20% = 80% 11B
118
LecturePLUS Timberlake
38
Learning Check AT8
Copper has two isotopes 63Cu (62.9
amu) and 65Cu (64.9 amu). What is the %
abundance of each isotope? (Hint:
Check periodic table for atomic mass)
1) 30%
2) 70%
3) 100%
119
LecturePLUS Timberlake
39
Solution AT8
2) 70%
Solution
62.9X + 6490 = 64.9X = 6350
-2.0 X = -140
X = 70%
120
LecturePLUS Timberlake
1
The Atom
Atomic Number and Mass
Number
Isotopes
121
LecturePLUS Timberlake
2
Atomic Theory
Atoms are building blocks of elements
Similar atoms in each element
Different from atoms of other elements
Two or more different atoms bond in simple
ratios to form compounds
122
LecturePLUS Timberlake
3
Subatomic Particles
Particle
Symbol
Charge
Relative
Mass
Electron
e-
1-
0
Proton p+
+
1
Neutron
n
0
1
123
LecturePLUS Timberlake
4
Location of Subatomic Particles
10-13 cm
electrons
protons
neutrons
10-8 cm
nucleus
124
LecturePLUS Timberlake
5
Atomic Number
Counts the number
of
protons
in an atom
125
LecturePLUS Timberlake
6
Periodic Table
Represents physical and chemical
behavior of elements
Arranges elements by increasing atomic
number
Repeats similar properties in columns
known as chemical families or groups
126
LecturePLUS Timberlake
7
Periodic Table
1
2
3 4 5 6 7
8
11
Na
127
LecturePLUS Timberlake
8
Atomic Number on the Periodic
Table
11
Na
Atomic Number
Symbol
128
LecturePLUS Timberlake
9
All atoms of an element have
the same number of protons
11
Na
11 protons
Sodium
129
LecturePLUS Timberlake
10
Learning Check AT 1
State the number of protons for atoms of each
of the following:
A. Nitrogen
1) 5 protons
2) 7 protons 3) 14
protons
B. Sulfur
1) 32 protons
2) 16 protons 3) 6 protons
C. Barium
1) 137 protons 2) 81 protons 3) 56 protons
130
LecturePLUS Timberlake
11
Solution AT 1
State the number of protons for atoms of each
of the following:
A. Nitrogen
2) 7 protons
B. Sulfur
2) 16 protons
C. Barium
3) 56 protons
131
LecturePLUS Timberlake
12
Number of Electrons
An atom is neutral
The net charge is zero
Number of protons = Number of electrons
Atomic number = Number of electrons
132
LecturePLUS Timberlake
13
Mass Number
Counts the number
of
protons and neutrons
in an atom
133
LecturePLUS Timberlake
14
Atomic Symbols
Show the mass number and atomic number
Give the symbol of the element
mass number
23 Na
sodium-23
atomic number11
134
LecturePLUS Timberlake
15
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
8 p+
15 p+
30 p+
8 n
16 n
35 n
8 e-
15e-
30 e-
135
LecturePLUS Timberlake
16
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
136
LecturePLUS Timberlake
17
More Atomic Symbols
16
31
65
O
P
Zn
8
15
30
8 p+
15 p+
30 p+
8 n
16 n
35 n
8 e-
15e-
30 e-
137
LecturePLUS Timberlake
18
Isotopes
Atoms with the same number of protons,
but different numbers of neutrons.
Atoms of the same element (same atomic
number) with different mass numbers
Isotopes of chlorine
35Cl
37Cl
17
17
chlorine - 35 chlorine - 37
138
LecturePLUS Timberlake
19
Learning Check AT 2
Naturally occurring carbon consists of three
isotopes, 12C, 13C, and 14C. State the number of
protons, neutrons, and electrons in each of
these carbon atoms.
12C
13C
14C
6
6
6
#P _______ _______ _______
#N _______ _______ _______
#E _______ _______ _______
139
LecturePLUS Timberlake
20
Solution AT 2
12C
13C
14C
6
6
6
#P __6___ _ 6___ ___6___
#N __6___ _ _7___ ___8___
#E __6___ _ 6___ ___6___
140
LecturePLUS Timberlake
21
Learning Check AT 3
An atom of zinc has a mass number of 65.
A.
Number of protons in the zinc atom
1) 30
2) 35
3) 65
B.
Number of neutrons in the zinc atom
1) 30
2) 35
3) 65
C. What is the mass number of a zinc isotope
with 37 neutrons?
1) 37
2) 65
3) 67
141
LecturePLUS Timberlake
22
Solution AT 3
An atom of zinc has a mass number of 65.
A.
Number of protons in the zinc atom
1) 30
B.
Number of neutrons in the zinc atom
2) 35
C. What is the mass number of a zinc isotope
with 37 neutrons?
3) 67
142
LecturePLUS Timberlake
23
Learning Check AT 4
Write the atomic symbols for atoms with the following:
A. 8 p+, 8 n, 8 e-
___________
B.
17p+, 20n, 17e-___________
C. 47p+, 60 n, 47 e-___________
143
LecturePLUS Timberlake
24
Solution AT 4
16O
A. 8 p+, 8 n, 8 e-
8
B.
17p+, 20n, 17e-37Cl
17
C. 47p+, 60 n, 47 e-107Ag
47
144
LecturePLUS Timberlake
25
Learning Check AT 5
An atom has 14 protons and 20 neutrons.
A.
Its atomic number is
1) 14
2) 16
3) 34
B. Its mass number is
1) 14
2) 16
3) 34
C. The element is
1) Si
2) Ca
3) Se
D.
Another isotope of this element is
1)34X
2)34X
3)36X
16
14 14
145
LecturePLUS Timberlake
26
Solution AT 5
An atom has 14 protons and 20 neutrons.
A.
It has atomic number
1) 14
B. It has a mass number of
3) 34
C. The element is
1) Si
D.
Another isotope of this element would be
3) 36X
14
146
LecturePLUS Timberlake
27
Masses of Atoms
A scale designed for atoms gives their small
atomic masses in atomic mass units (amu)
An atom of 12C was assigned an exact mass of
12.00 amu
Relative masses of all other atoms was
determined by comparing each to the mass of
12C
An atom twice as heavy has a mass of 24.00
amu. An atom half as heavy is 6.00 amu.
147
LecturePLUS Timberlake
28
Atomic Mass
Listed on the periodic table
Gives the mass of “average” atom of each
element compared to 12C
Average atom based on all the isotopes and their
abundance %
Atomic mass is not a whole number
Na
22.99
148
LecturePLUS Timberlake
29
Learning Check AT6
Using the periodic table, specify the atomic
mass of each element (round to the tenths
place):
A.
calcium
__________
B. aluminum
__________
C.
lead __________
D. barium __________
E. iron
__________
149
LecturePLUS Timberlake
30
Solution AT6
Using the periodic table, specify the atomic
mass of each element (round to the tenths
place):
A.
calcium
_40.1 amu _
B. aluminum
_27.0 amu _
C.
lead _207.2 amu_
D. barium _137.3 amu_
E. iron
_55.8 amu__
150
LecturePLUS Timberlake
31
Calculating Atomic Mass
Percent(%) abundance of isotopes
Mass of each isotope of that element
Weighted average =
mass isotope1(%) + mass isotope2(%) + …
100
100
151
LecturePLUS Timberlake
32
Atomic Mass of Magnesium
Isotopes Mass of Isotope Abundance
24Mg
=
24.0 amu
78.70%
25Mg
=
25.0 amu
10.13%
26Mg
= 26.0 amu
11.17%
Atomic mass (average mass) Mg = 24.3 amu
Mg
24.3
152
LecturePLUS Timberlake
33
Learning Check AT7
Gallium is a metallic element found in
small lasers used in compact disc players.
In a sample of gallium, there is 60.2% of
gallium-69 (68.9 amu) atoms and 39.8% of
gallium-71 (70.9 amu) atoms. What is the
atomic mass of gallium?
153
LecturePLUS Timberlake
34
Solution AT7
Ga-69
68.9 amu x 60.2 = 41.5 amu for 69Ga
100
Ga-71 (%/100)
70.9 amu x 39.8
=
28.2 amu for 71Ga
100
Atomic mass Ga
=
69.7 amu
154
LecturePLUS Timberlake
35
Finding An Isotopic Mass
A sample of boron consists of 10B (mass
10.0 amu) and 11B (mass 11.0 amu). If
the average atomic mass of B is 10.8
amu, what is the % abundance of each
boron isotope?
155
LecturePLUS Timberlake
36
Assign X and Y values:
X = % 10B Y = % 11B
Determine Y in terms of X
X + Y = 100
Y = 100 - X
Solve for X:
X (10.0) + (100 - X )(11.0) = 10.8
100 100
Multiply through by 100
10.0 X + 1100 - 11.0X = 1080
156
LecturePLUS Timberlake
37
Collect X terms
10.0 X - 11.0 X = 1080 - 1100
- 1.0 X = -20
X = -20 = 20 % 10B
- 1.0
Y = 100 - X
% 11B = 100 - 20% = 80% 11B
157
LecturePLUS Timberlake
38
Learning Check AT8
Copper has two isotopes 63Cu (62.9
amu) and 65Cu (64.9 amu). What is the %
abundance of each isotope? (Hint:
Check periodic table for atomic mass)
1) 30%
2) 70%
3) 100%
158
LecturePLUS Timberlake
39
Solution AT8
2) 70%
Solution
62.9X + 6490 = 64.9X = 6350
-2.0 X = -140
X = 70%
LecturePLUS Timberlake
1
The Atom
Atomic Number and Mass
Number
Isotopes
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