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2. Standardized Test Prep Image and Math Focus Bank
Resources
Chapter Presentation
Bellringers
Transparencies
Standardized Test Prep
Image and Math Focus Bank
Visual Concepts

3. Chapter K4 Table of Contents
Introduction to Atoms
Table of Contents
Section 1 Development of the Atomic Theory
Section 2 The Atom

4. Section 1 Development of the Atomic Theory
Chapter K4
Bellringer
The following is a quote by Democritus (c. 460–c. 370 bce). Paraphrase this quote in your own words in your science journal.
“Color exists by convention, sweet by convention, bitter by convention; in reality nothing exists but atoms and the void.”
What do you know about Democritus? And why are his thoughts important?

5. Section 1 Development of the Atomic Theory
Chapter K4
Objectives
Describe some of the experiments that led to the current atomic theory.
Compare the different models of the atom.
Explain how the atomic theory has changed as scientists have discovered new information about the atom.

6. The Beginning of the Atomic Theory
Section 1 Development of the Atomic Theory
Chapter K4
The Beginning of the Atomic Theory
What Is an Element? Around 440 BCE, a Greek philosopher named Democritus thought that you would eventually end up with a particle that could not be cut. He called this particle an atom.
From Aristotle to Modern Science Aristotle, another Greek philosopher, disagreed with Democritus’s ideas. He believed that you would never end up with a particle that could not be cut.

7. The Beginning of the Atomic Theory, continued
Section 1 Development of the Atomic Theory
Chapter K4
The Beginning of the Atomic Theory, continued
From Aristotle to Modern Science Democritus was right, though: Matter is made of particles, which we call atoms. An atom is the smallest particle into which an element can be divided and still be the same substance.

8. Dalton’s Atomic Theory Based on Experiments
Section 1 Development of the Atomic Theory
Chapter K4
Dalton’s Atomic Theory Based on Experiments
Dalton’s Theory John Dalton published his atomic theory in His theory stated that all substances are made of atoms. Atoms are small particles that cannot be created, divided, or destroyed. Atoms of the same element are exactly alike, and atoms of different elements are different. Atoms join with other atoms to make new substances.
Not Quite Correct The atomic theory was then changed to describe the atom more correctly.

9. Thomson’s Discovery of Electrons
Section 1 Development of the Atomic Theory
Chapter K4
Thomson’s Discovery of Electrons
Negatively Charged Particles Thomson experimented with a cathode-ray tube like the one shown on the next slide. He discovered negatively charged particles that are now known as electrons.
Like Plums in Pudding After learning that atoms contain electrons, Thomson proposed a new model of the atom. Thomson thought that electrons were mixed throughout an atom, like plums in a pudding.

10. Section 1 Development of the Atomic Theory
Chapter K4

11. Rutherford’s Atomic “Shooting Gallery”
Section 1 Development of the Atomic Theory
Chapter K4
Rutherford’s Atomic “Shooting Gallery”
Negatively Charged Particles In 1909, Ernest Rutherford aimed a beam of small, positively charged particles at a thin sheet of gold foil. The next slide shows his experiment.
Surprising Results Rutherford expected the particles to pass right through the gold in a straight line. To Rutherford’s great surprise, some of the particles were deflected.

12. Section 1 Development of the Atomic Theory
Chapter K4

13. Where Are the Electrons?
Section 1 Development of the Atomic Theory
Chapter K4
Where Are the Electrons?
Far from the Nucleus Rutherford proposed that in the center of the atom is a tiny, positively charged part called the nucleus.
Bohr’s Electron Levels In 1913, Niels Bohr proposed that electrons move around the nucleus in certain paths, or energy levels.

14. Where Are the Electrons?, continued
Section 1 Development of the Atomic Theory
Chapter K4
Where Are the Electrons?, continued
The Modern Atomic Theory According to the current theory, there are regions inside the atom where electrons are likely to found. These regions are called electron clouds.

15. Comparing Models of the Atom
Section 1 Development of the Atomic Theory
Chapter K4
Comparing Models of the Atom
Click below to watch the Visual Concept.
You may stop the video at any time by pressing the Esc key.
Visual Concept

16. Chapter K4
Section 2 The Atom
Bellringer
Answer the following question: An atom is the smallest particle into which an element can be divided and still be that element. Now that scientists have learned that an atom is made up of even smaller particles, is this definition still accurate?
Explain your answer in your science journal.

17. Chapter K4 Objectives Describe the size of an atom.
Section 2 The Atom
Chapter K4
Objectives
Describe the size of an atom.
Name the parts of an atom.
Describe the relationship between numbers of protons and neutrons and atomic number.

18. Chapter K4 Objectives, continued State how isotopes differ.
Section 2 The Atom
Chapter K4
Objectives, continued
State how isotopes differ.
Calculate atomic masses.
Describe the forces within an atom.

19. Chapter K4 How Small Is an Atom?
Section 2 The Atom
Chapter K4
How Small Is an Atom?
Three One-Hundred-Millionths of a Centimeter! Scientists know that aluminum is made of average-sized atoms. An aluminum atom has a diameter of about cm.

20. Chapter K4 What Is an Atom Made Of?
Section 2 The Atom
Chapter K4
What Is an Atom Made Of?
The Nucleus Protons are positively charged particles in the nucleus. Neutrons are the particles of the nucleus that have no electrical charge.
Outside the Nucleus Electrons are the negatively charged particles in atoms. Electrons are found around the nucleus within electron clouds. All the structures of the atom can be seen on the next slide.

21. Section 2 The Atom
Chapter K4

22. How Do Atoms of Different Elements Differ?
Section 2 The Atom
Chapter K4
How Do Atoms of Different Elements Differ?
Starting Simply The hydrogen atom has one proton and one electron.
Now for Some Neutrons The helium atom has two protons, two neutrons, and two electrons.

23. How Do Atoms of Different Elements Differ?
Section 2 The Atom
Chapter K4
How Do Atoms of Different Elements Differ?
Building Bigger Atoms For bigger atoms, simply add protons, neutrons, and electrons.
Protons and Atomic Number The number of protons in the nucleus of an atom is the atomic number of that atom. All atoms of an element have the same atomic number.

24. Section 2 The Atom
Chapter K4
Isotopes
Isotopes are atoms that have the same number of protons but have different numbers of neutrons.

25. Chapter K4 Isotopes, continued
Section 2 The Atom
Chapter K4
Isotopes, continued
Properties of Isotopes An unstable atom is an atom with a nucleus that will change over time. This type of isotope is radioactive.
Telling Isotopes Apart You can identify each isotope of an element by its mass number. The mass number is the sum of the protons and neutrons in an atom.

26. Section 2 The Atom
Chapter K4
Isotopes, continued

27. Chapter K4 Isotopes, continued
Section 2 The Atom
Chapter K4
Isotopes, continued
Naming Isotopes To identify a specific isotope of an element, write the name of the element followed by a hyphen and the mass number of the isotope.
Calculating the Mass of an Element The atomic mass of an element is the weighted average of the masses of all the naturally occurring isotopes of that element.

28. Section 2 The Atom
Chapter K4

29. Chapter K4 Forces in Atoms
Section 2 The Atom
Chapter K4
Forces in Atoms
Four Basic Forces Four basic forces are at work everywhere, even within the atom. These forces are gravitational force, electromagnetic force, strong force, and weak force.
These forces work together to give an atom its structure and properties.

30. Section 2 The Atom
Chapter K4

31. Chapter K4
Introduction to Atoms
Concept Map
Use the terms below to complete the concept map on the next slide.
a nucleus
mass number
isotopes
protons
atoms
electrons
atomic number

32. Chapter K4
Introduction to Atoms

33. Chapter K4
Introduction to Atoms

34. End of Chapter K4 Show

35. Chapter K4
Standardized Test Preparation
Reading
Read each of the passages. Then, answer the questions that follow each passage.

36. Chapter K4
Standardized Test Preparation
Passage 1 In the Bohr model of the atom, electrons can be found only in certain energy levels. Electrons “jump” from one level to the next level without passing through any of the regions in between. When an electron moves from one level to another,
it gains or loses energy, depending on the direction of its jump. Bohr’s model explained an unusual event. When electric charges pass through atoms of a gaseous element, the gas produces a glowing light, like in a neon sign.
Continued on the next slide

37. Chapter K4
Standardized Test Preparation
Passage 1, continued If this light is passed through a prism, a pattern of lines appears, each line having a different color. The pattern depends on the element—neon has one pattern, and helium has another. In Bohr’s model, the lines are caused by
electron jumps from higher to lower energy levels. Because only certain jumps are possible, electrons release energy only in certain quantities. These “packets” of energy produce the lines that are seen.

38. Chapter K4
Standardized Test Preparation
1. In the Bohr model of the atom, what limitation is placed on electrons?
A the number of electrons in an atom
B the electrons’ being found only in certain energy levels
C the size of electrons
D the speed of electrons

39. Chapter K4
Standardized Test Preparation
1. In the Bohr model of the atom, what limitation is placed on electrons?
A the number of electrons in an atom
B the electrons’ being found only in certain energy levels
C the size of electrons
D the speed of electrons

40. Chapter K4
Standardized Test Preparation
2. What causes the colored lines that appear when the light from a gas is passed through a prism?
F packets of energy released by electron jumps
G electrons changing color
H atoms of the gas exchanging electrons
I There is not enough information to determine the answer.

41. Chapter K4
Standardized Test Preparation
2. What causes the colored lines that appear when the light from a gas is passed through a prism?
F packets of energy released by electron jumps
G electrons changing color
H atoms of the gas exchanging electrons
I There is not enough information to determine the answer.

42. Chapter K4
Standardized Test Preparation
Passage 2 No one has ever seen a living dinosaur, but scientists have determined the appearance of Tyrannosaurus rex by studying fossilized skeletons. Scientists theorize that these extinct creatures had big hind legs, small front legs, a long, whip-like tail, and a mouth full of dagger-shaped teeth. However, theories of how T. rex walked have been harder to develop. For many years, most scientists thought that T. rex plodded slowly like a big, lazy lizard.
Continued on the next slide

43. Chapter K4
Standardized Test Preparation
Passage 2, continued However, after studying well-preserved dinosaur tracks and noticing skeletal similarities between certain dinosaur fossils and living creatures like the ostrich, many scientists now theorize that T. rex could turn on the speed. Some scientists estimate that T. rex had bursts of speed of 32 km/h (20 mi/h)!

44. Chapter K4
Standardized Test Preparation
1. According to this passage, where does most of what we know about the appearance of Tyrannosaurus rex come from?
A fossilized skeletons
B dinosaur tracks
C living organisms such as the ostrich
D living specimens of T. rex

45. Chapter K4
Standardized Test Preparation
1. According to this passage, where does most of what we know about the appearance of Tyrannosaurus rex come from?
A fossilized skeletons
B dinosaur tracks
C living organisms such as the ostrich
D living specimens of T. rex

46. Chapter K4
Standardized Test Preparation
2. How did scientists conclude that T. rex could probably move very quickly?
F They measured the speed at which it could run.
G They compared fossilized T. rex tracks with T. rex skeletons.
H They studied dinosaur tracks and noted similarities between ostrich skeletons and T. rex skeletons.
I They measured the speed at which ostriches could run.

47. Chapter K4
Standardized Test Preparation
2. How did scientists conclude that T. rex could probably move very quickly?
F They measured the speed at which it could run.
G They compared fossilized T. rex tracks with T. rex skeletons.
H They studied dinosaur tracks and noted similarities between ostrich skeletons and T. rex skeletons.
I They measured the speed at which ostriches could run.

48. Interpreting Graphics
Chapter K4
Standardized Test Preparation
Interpreting Graphics
Use the diagram of an atom below to answer the questions that follow.

49. Chapter K4
Standardized Test Preparation
1. The black circles in the center of the model represent neutrons. What do the white circles in the center represent?
A electrons
B protons
C nuclei
D atoms

50. Chapter K4
Standardized Test Preparation
1. The black circles in the center of the model represent neutrons. What do the white circles in the center represent?
A electrons
B protons
C nuclei
D atoms

51. Chapter K4 2. What is the mass number of the atom shown in the model?
Standardized Test Preparation
2. What is the mass number of the atom shown in the model?
F 3
G 7
H 9
I 11

52. Chapter K4 2. What is the mass number of the atom shown in the model?
Standardized Test Preparation
2. What is the mass number of the atom shown in the model?
F 3
G 7
H 9
I 11

53. Chapter K4
Standardized Test Preparation
3. What is the overall charge of the atom shown in the model?
A 12
B 11
C 0
D 21

54. Chapter K4
Standardized Test Preparation
3. What is the overall charge of the atom shown in the model?
A 12
B 11
C 0
D 21

55. Chapter K4 Math Read each question, and choose the best answer.
Standardized Test Preparation
Math
Read each question, and choose the best answer.

56. Chapter K4
Standardized Test Preparation
1. Aimee, Mari, and Brooke are 163 cm, 171 cm, and 175 cm tall. Which of the following measurements is a reasonable average height of these three friends?
A 170 cm
B 175 cm
C 255 cm
D 509 cm

57. Chapter K4
Standardized Test Preparation
1. Aimee, Mari, and Brooke are 163 cm, 171 cm, and 175 cm tall. Which of the following measurements is a reasonable average height of these three friends?
A 170 cm
B 175 cm
C 255 cm
D 509 cm

58. Chapter K4
Standardized Test Preparation
2. A certain school has 40 classrooms. Most of the classrooms have 25 to 30 students. Which of the following is a reasonable estimate of the number of students that go to this school?
F 40 students
G 100 students
H 1,100 students
I 2,000 students

59. Chapter K4
Standardized Test Preparation
2. A certain school has 40 classrooms. Most of the classrooms have 25 to 30 students. Which of the following is a reasonable estimate of the number of students that go to this school?
F 40 students
G 100 students
H 1,100 students
I 2,000 students

60. Chapter K4
Standardized Test Preparation
3. Jenna is setting up a fish tank in her room. The tank is the shape of a rectangular prism. The height of the tank is 38 cm, the width is 23 cm, and the length is 62 cm. The tank is filled with water to a point that is 7 cm from the top. How much water is in the tank?
A 44,206 cm3
B 48,070 cm3
C 54,188 cm3
D 64,170 cm3

61. Chapter K4
Standardized Test Preparation
3. Jenna is setting up a fish tank in her room. The tank is the shape of a rectangular prism. The height of the tank is 38 cm, the width is 23 cm, and the length is 62 cm. The tank is filled with water to a point that is 7 cm from the top. How much water is in the tank?
A 44,206 cm3
B 48,070 cm3
C 54,188 cm3
D 64,170 cm3

62. Chapter K4 4. Which of the following is equal to 85?
Standardized Test Preparation
4. Which of the following is equal to 85?
F 8  8  8  8  8
G 5  5  5  5  5  5  5  5
H 5  8
I 8  8  8  8  8

63. Chapter K4 4. Which of the following is equal to 85?
Standardized Test Preparation
4. Which of the following is equal to 85?
F 8  8  8  8  8
G 5  5  5  5  5  5  5  5
H 5  8
I 8  8  8  8  8

64. Section 1 Development of the Atomic Theory
Chapter K4

65. Section 1 Development of the Atomic Theory
Chapter K4

66. Section 2 The Atom
Chapter K4

67. Section 2 The Atom
Chapter K4

68. Section 2 The Atom
Chapter K4

69. Chapter K4
Standardized Test Preparation

70. Section 2 The Atom
Chapter K4