The Atom
Atomic Number and Mass
Number
Isotopes
LecturePLUS Timberlake

1
Atomic Theory

Atoms are building blocks of elements
Similar atoms in each element
Different from atoms of other elemen...
Subatomic Particles
Particle

Symbol

Charge

Relative
Mass

Electron

e-

1-

0

Proton

p+

+

1

Neutron

n

0

1

Lect...
Location of Subatomic Particles
10-13 cm
electrons
protons
nucleus

10-8 cm

LecturePLUS Timberlake

neutrons

4
Atomic Number
Counts the number
of
protons
in an atom

LecturePLUS Timberlake

5
Periodic Table
Represents physical and chemical
behavior of elements
Arranges elements by increasing atomic
number
Repe...
Periodic Table
1

2

3

4

5

6

7

8

11
Na

LecturePLUS Timberlake

7
Atomic Number on the Periodic
Table
Atomic Number

Symbol

11

Na
LecturePLUS Timberlake

8
All atoms of an element have
the same number of protons
11 protons

Sodium

11

Na
LecturePLUS Timberlake

9
Learning Check AT 1
State the number of protons for atoms of each
of the following:
A. Nitrogen
1) 5 protons
2) 7 protons ...
Solution AT 1
State the number of protons for atoms of each
of the following:
A. Nitrogen
2) 7 protons
B. Sulfur
2) 16 pro...
Number of Electrons

An atom is neutral
The net charge is zero
Number of protons = Number of electrons
Atomic number =...
Mass Number

Counts the number
of
protons and neutrons
in an atom

LecturePLUS Timberlake

13
Atomic Symbols
Show the mass number and atomic number
Give the symbol of the element
mass number
23

atomic number

Na

...
More Atomic Symbols

16

31

O
8

8 p+
8n
8 e-

65

P
15

Zn
30

15 p+
30 p+
16 n
35 n
LecturePLUS
15 e- Timberlake
30 e-
...
Isotopes
Atoms with the same number of protons,
but different numbers of neutrons.
Atoms of the same element (same atomi...
Learning Check AT 2
Naturally occurring carbon consists of three
isotopes, 12C, 13C, and 14C. State the number of
protons,...
Solution AT 2
C

12

6

C

13
6

14
6

C

#P __6___

_ 6___

___6___

#N __6___

_ _7___

___8___

#E __6___

_ 6___

___6...
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. Nu...
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 i...
Learning Check AT 4
Write the atomic symbols for atoms with
the following:
A. 8 p+, 8 n, 8 e-

___________

B. 17p+, 20n, ...
Solution AT 4
O

16

A. 8 p+, 8 n, 8 e-

8

B. 17p+, 20n, 17e-

37
17

Cl

C. 47p+, 60 n, 47 e- 107Ag
47
LecturePLUS Timbe...
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 i...
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. Th...
Masses of Atoms
A scale designed for atoms gives their small
atomic masses in atomic mass units (amu)
An atom of 12C was...
Atomic Mass

Na
22.99

Listed on the periodic table
Gives the mass of “average” atom of each
element compared to 12C
Av...
Learning Check AT6
Using the periodic table, specify the
atomic mass of each element (round to the
tenths place):
A. calci...
Solution AT6
Using the periodic table, specify the
atomic mass of each element (round to the
tenths place):
A. calcium

_4...
Calculating Atomic Mass
Percent(%) abundance of isotopes
Mass of each isotope of that element
Weighted average =
mass i...
Atomic Mass of Magnesium
Isotopes
24
Mg
=

Mass of Isotope
24.0 amu

Abundance
78.70%

Mg

=

25.0 amu

10.13%

Mg

=

26....
Learning Check AT7
Gallium is a metallic element found in
small lasers used in compact disc players.
In a sample of galliu...
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
100

=

Atomic mass Ga =

2...
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 ...
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 ...
Collect X terms
10.0 X - 11.0 X

=

1080 - 1100

- 1.0 X = -20
X

=

-20
- 1.0

=

Y = 100 - X
% 11B = 100 - 20% =

20 %

...
Learning Check AT8
Copper has two isotopes 63Cu (62.9
amu) and 65Cu (64.9 amu). What is the %
abundance of each isotope? (...
Solution AT8
2) 70%
Solution
62.9X + 6490 = 64.9X = 6350
-2.0 X = -140
X = 70%
LecturePLUS Timberlake

37
Upcoming SlideShare
Loading in …5
×

Atomic mass

488 views

Published on

Published in: Technology
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
488
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
12
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Atomic mass

  1. 1. The Atom Atomic Number and Mass Number Isotopes LecturePLUS Timberlake 1
  2. 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 LecturePLUS Timberlake 2
  3. 3. Subatomic Particles Particle Symbol Charge Relative Mass Electron e- 1- 0 Proton p+ + 1 Neutron n 0 1 LecturePLUS Timberlake 3
  4. 4. Location of Subatomic Particles 10-13 cm electrons protons nucleus 10-8 cm LecturePLUS Timberlake neutrons 4
  5. 5. Atomic Number Counts the number of protons in an atom LecturePLUS Timberlake 5
  6. 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 LecturePLUS Timberlake 6
  7. 7. Periodic Table 1 2 3 4 5 6 7 8 11 Na LecturePLUS Timberlake 7
  8. 8. Atomic Number on the Periodic Table Atomic Number Symbol 11 Na LecturePLUS Timberlake 8
  9. 9. All atoms of an element have the same number of protons 11 protons Sodium 11 Na LecturePLUS Timberlake 9
  10. 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 C. Barium 1) 137 protons 2) 81 protons LecturePLUS Timberlake 3) 6 protons 3) 56 protons 10
  11. 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 LecturePLUS Timberlake 11
  12. 12. Number of Electrons An atom is neutral The net charge is zero Number of protons = Number of electrons Atomic number = Number of electrons LecturePLUS Timberlake 12
  13. 13. Mass Number Counts the number of protons and neutrons in an atom LecturePLUS Timberlake 13
  14. 14. Atomic Symbols Show the mass number and atomic number Give the symbol of the element mass number 23 atomic number Na sodium-23 11 LecturePLUS Timberlake 14
  15. 15. More Atomic Symbols 16 31 O 8 8 p+ 8n 8 e- 65 P 15 Zn 30 15 p+ 30 p+ 16 n 35 n LecturePLUS 15 e- Timberlake 30 e- 15
  16. 16. 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 35 17 Cl chlorine - 35 37 17 Cl chlorine - 37 LecturePLUS Timberlake 16
  17. 17. 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. C C 12 6 13 6 14 C 6 #P _______ _______ _______ #N _______ _______ _______ _______ _______ #E _______ LecturePLUS Timberlake 17
  18. 18. Solution AT 2 C 12 6 C 13 6 14 6 C #P __6___ _ 6___ ___6___ #N __6___ _ _7___ ___8___ #E __6___ _ 6___ ___6___ LecturePLUS Timberlake 18
  19. 19. 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 LecturePLUS Timberlake 19
  20. 20. 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 LecturePLUS Timberlake 20
  21. 21. 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- ___________ LecturePLUS Timberlake 21
  22. 22. Solution AT 4 O 16 A. 8 p+, 8 n, 8 e- 8 B. 17p+, 20n, 17e- 37 17 Cl C. 47p+, 60 n, 47 e- 107Ag 47 LecturePLUS Timberlake 22
  23. 23. 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 16 14 2) 34X 14 LecturePLUS Timberlake 3) 36X 23
  24. 24. 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 LecturePLUS Timberlake 24
  25. 25. 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 12 C An atom twice as heavy has a mass of 24.00 amu. An atom half as heavy is 6.00 amu. 25 LecturePLUS Timberlake
  26. 26. Atomic Mass Na 22.99 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 LecturePLUS Timberlake 26
  27. 27. 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 __________ LecturePLUS Timberlake 27
  28. 28. 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__ LecturePLUS Timberlake 28
  29. 29. Calculating Atomic Mass Percent(%) abundance of isotopes Mass of each isotope of that element Weighted average = mass isotope1(%) + mass isotope2(%) + … 100 100 LecturePLUS Timberlake 29
  30. 30. Atomic Mass of Magnesium Isotopes 24 Mg = Mass of Isotope 24.0 amu Abundance 78.70% Mg = 25.0 amu 10.13% Mg = 26.0 amu 11.17% 25 26 Atomic mass (average mass) Mg = 24.3 amu Mg 24.3 LecturePLUS Timberlake 30
  31. 31. 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? LecturePLUS Timberlake 31
  32. 32. Solution AT7 Ga-69 68.9 amu x 60.2 = 41.5 amu for 69Ga 100 Ga-71 (%/100) 70.9 amu x 39.8 100 = Atomic mass Ga = 28.2 amu for 71Ga 69.7 amu LecturePLUS Timberlake 32
  33. 33. 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? LecturePLUS Timberlake 33
  34. 34. 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) 100 100 = 10.8 Multiply through by 100 10.0 X + 1100 - 11.0X = 1080 LecturePLUS Timberlake 34
  35. 35. Collect X terms 10.0 X - 11.0 X = 1080 - 1100 - 1.0 X = -20 X = -20 - 1.0 = Y = 100 - X % 11B = 100 - 20% = 20 % B 10 80% 11B LecturePLUS Timberlake 35
  36. 36. 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% LecturePLUS Timberlake 3) 100% 36
  37. 37. Solution AT8 2) 70% Solution 62.9X + 6490 = 64.9X = 6350 -2.0 X = -140 X = 70% LecturePLUS Timberlake 37

×