1. Matter – Properties and Change
CHAPTER 4
Matter – Properties and Change

2. National Standards for Chapter 4
UCP.2 Evidence, models, and explanation
A.1 Abilities necessary to do scientific inquiry
B.1 Structure of atoms
B.2 Structure and properties of matter

3. Vocabulary/Study Guide
Define each term using the Glossary
Either write on the handout, or use your own paper
This is due on Test Day (tentatively, Friday, October 11)

4. Section 1: Early Ideas About Matter
National Standards:
UCP.2 Evidence, models, and explanation
A.1 Abilities necessary to do scientific inquiry
B.1 Structure of atoms
B.2 Structure and properties of matter

5. Objectives – Section 1
Compare and contrast the atomic models of Democritus, Aristotle, and Dalton.
Understand how Dalton's theory explains the conservation of mass.
REVIEW VOCABULARY:
theory: an explanation supported by many experiments; is still subject to new experimental data, can be modified, and is considered successful if it can be used to make predictions that are true

6. New Vocabulary Dalton’s atomic theory
The ancient Greeks tried to explain matter, but the scientific study of the atom began with John Dalton in the early 1800's.

7. Early Ideas About Matter
Many ancient scholars believed matter was composed of such things as earth, water, air, and fire.
Many believed matter could be endlessly divided into smaller and smaller pieces.

8. Early Ideas About Matter
Democritus (460–370 B.C.) was the first person to propose the idea that matter was not infinitely divisible, but made up of individual particles called atomos, from which the English word atom is derived.
Aristotle (484–322 B.C.) disagreed with Democritus because he did not believe empty space could exist.
Aristotle’s views went unchallenged for 2,000 years until science developed methods to test the validity of his ideas.

9. Early Ideas About Matter

10. Early Ideas About Matter
John Dalton revived the idea of the atom in the early 1800s based on numerous chemical reactions.
Dalton’s atomic theory easily explained conservation of mass in a reaction as the result of the combination, separation, or rearrangement of atoms.

11. Early Ideas About Matter

12. Early Ideas About Matter
Ancient Greeks
John Dalton
Matter is composed of atoms, which move through empty space
Atoms are solid, homogeneous, indestructible, and indivisible
Different kinds of atoms have different sizes and shapes
Size, shape, and movement of atoms determine the properties of matter
Matter is composed of extremely small articles called atoms
Atoms are indivisible and indestructible
Atoms of a given element are identical in size, mass, and chemical properties
Atoms of a specific element are different from those of another element
Different atoms combine in simple whole-number ratios to form compounds
In a chemical reaction, atoms are separated, combined, or rearranged

13. Homework, Section 1 SECTION 1 REVIEW, Page 105 Questions #1, 4-6
Answer with complete sentences
Finish filling in charts that were handed out in class: Compare and contrast early ideas of the atom vs. John Dalton’s ideas of the atom
Due tomorrow

14. Section 2: Changes in Matter
National Standards:
UCP.2 Evidence, models, and explanation
B.1 Structure of atoms
B.2 Structure and properties of matter

15. Objectives – Section 2 Review Vocabulary: Define atom.
Distinguish between the subatomic particles in terms of relative charge and mass.
Describe the structure of the atom, including the locations of the subatomic particles.
Review Vocabulary:
model: a visual, verbal, and/or mathematical explanation of data collected from many experiments

16. New Vocabulary atom nucleus cathode ray proton electron neutron
An atom is made of a nucleus containing protons and neutrons; electrons move around the nucleus.

17. The Atom
The smallest particle of an element that retains the properties of the element is called an atom.
An instrument called the scanning tunneling microscope (STM) allows individual atoms to be seen.

18. The Electron
When an electric charge is applied, a ray of radiation travels from the cathode to the anode, called a cathode ray.
Cathode rays are a stream of particles carrying a negative charge.
The particles carrying a negative charge are known as electrons.

19. The Electron
This figure shows a typical cathode ray tube.

20. The Electron
J.J. Thomson measured the effects of both magnetic and electric fields on the cathode ray to determine the charge-to-mass ratio of a charged particle, then compared it to known values.
The mass of the charged particle was much less than a hydrogen atom, then the lightest known atom.
Thomson received the Nobel Prize in 1906 for identifying the first subatomic particle—the electron

21. The Electron
In the early 1910s, Robert Millikan used the oil-drop apparatus shown below to determine the charge of an electron.

22. The Electron
Charges change in discrete amounts—1.602  10–19 coulombs, the charge of one electron (now equated to a single unit, 1–).
With the electron’s charge and charge-to-mass ratio known, Millikan calculated the mass of a single electron.
the mass of a hydrogen atom

23. Transparency 11: Cathode Ray Experiments

24. The Electron
Matter is neutral. You know that matter is neutral from everyday experiences. You do not receive an electric shock (except under certain conditions) when you touch an object.
If electrons are negative, then how is matter, which is made up of electrons, neutral?
J.J. Thomson proposed a model of the atom to answer this question.

25. The Electron
J.J. Thomson's plum pudding model of the atom states that the atom is a uniform, positively charged sphere containing electrons.

26. The Nucleus
In 1911, Ernest Rutherford studied how positively charged alpha particles interacted with solid matter.
By aiming the particles at a
thin sheet of gold foil,
Rutherford expected the
paths of the alpha particles
to be only slightly altered by
a collision with an electron.

27. The Nucleus
Although most of the alpha particles went through the gold foil, a few of them bounced back, some at large angles.

28. The Nucleus Rutherford concluded that atoms are mostly empty space.
Almost all of the atom's positive charge and almost all of its mass is contained in a dense region in the center of the atom called the nucleus.
Electrons are held within the atom by their attraction to the positively charged nucleus.

29. The Nucleus
The repulsive force between the positively charged nucleus and positive alpha particles caused the deflections.

30. The Nucleus
Rutherford refined the model to include positively charged particles in the nucleus called protons.
James Chadwick received the Nobel Prize in 1935 for discovering the existence of neutrons, neutral particles in the nucleus which accounts for the remainder of an atom’s mass.

31. Transparency 12: Understanding Rutherford’s Gold Foil Experiment

32. The Nucleus
All atoms are made of three fundamental subatomic particles: the electron, the proton, and the neutron.
Atoms are spherically shaped.
Atoms are mostly empty space, and electrons travel around the nucleus held by an attraction to the positively charged nucleus.

33. The Nucleus
Scientists have determined that protons and neutrons are composed of subatomic particles called quarks.

34. The Nucleus
Scientists do not yet understand if or how quarks affect chemical behavior.
Chemical behavior can be explained by considering only an atom's electrons.

35. Homework, Section 2 SECTION 2 REVIEW, Page 114
Questions #7-11 – Answer with complete sentences
Due tomorrow

36. Section 3: How Atoms Differ
National Standards:
B.1 Structure of atoms

37. Objectives – Section 3
Explain the role of atomic number in determining the identity of an atom.
Define an isotope.
Explain why atomic masses are not whole numbers.
Calculate the number of electrons, protons, and neutrons in an atom given its mass number and atomic number.
Review Vocabulary:
substance: a form of matter that has a uniform and unchanging composition; also known as a pure substance

38. New Vocabulary atomic number mass number isotopes atomic mass
atomic mass unit (amu)
The number of protons and the mass number define the type of atom.
Review Vocabulary
periodic table: a chart that organizes all known elements into a grid of horizontal rows (periods) and vertical columns (groups or families) arranged by increasing atomic number

39. Atomic Number
Each element contains a unique positive charge in their nucleus.
The number of protons in the nucleus of an atom identifies the element and is known as the element’s atomic number.

40. Transparency 3: The Periodic Chart

41. Atomic Number Practice Problems #12-15 on Page 116
Write the problem, then the answer
Use the same paper as Transparency 3: The Periodic Chart

42. Periodic Table (pg. 116 TE) Dmitri Mendeleev (pg. 85)
Henry Moseley (pg. 115)
Classification based on the similarities and masses of the elements
Observed periodic patterns in the properties of the elements
Eight columns with up to seventeen elements in each column
Many missing elements
Each element has a unique positive charge in its nucleus
Used X-rays to calculate the size of the nucleus
Organized left-to-right and top-to-bottom by increasing atomic number
Horizontally – 7 periods Vertically – 8 families

43. Isotopes and Mass Number
All atoms of a particular element have the same number of protons and electrons but the number of neutrons in the nucleus can differ.
Atoms with the same number of protons but different numbers of neutrons are called isotopes.

44. Isotopes and Mass Number
In nature, most elements are found as mixtures of isotopes. Usually, the relative abundance of each isotope is constant.
Ex. In a banana, 93.26% is potassium-39, 6.73% is potassium-41 and 0.01% is potassium-40. In another banana or in a different source of potassium, the percentage composition of the potassium isotopes will still be the same.
Isotopes containing more neutrons have a greater mass.
Isotopes of an atom have the same chemical behavior.

45. Isotopes and Mass Number
The mass number is the sum of the protons and neutrons in the nucleus.

46. Transparency 13: Isotopes

47. Isotopes and Mass Number
Practice problems #16-17 on Page 118
Write the problem, then the answer
Use the same paper as Transparency 13: Isotopes and Mass Number

48. Mass of Atoms
One atomic mass unit (amu) is defined as 1/12th the mass of a carbon-12 atom.
One amu is nearly, but not exactly, equal to one proton and one neutron.

49. Mass of Atoms
The atomic mass of an element is the weighted average mass of the isotopes of that element.

50. TITLE: Calculate the Atomic Mass of the Element “Snackium” (pg
TITLE: Calculate the Atomic Mass of the Element “Snackium” (pg. 126) OBJECTIVE: Observe the impact of the weights of different sub-atomic particles on the element; Infer the importance of each type of particle to the final weight of the element PRE-LAB: First, read the entire Lab on Page What sub-atomic particles do the different types of snacks represent? 2. The mass of neutrons and protons is much greater than the mass of electrons; therefore, the mass of an element is dominated by the mass of the nucleus. Predict which, if any, types of snacks will dominate the mass of your imaginary element. 3. How will the mass of an isotope differ from the mass of the element? DATA: Glue or paste the data table into your Lab Book

51. Math Skills Transparency 4: Calculating Atomic Mass

52. Mass of Atoms Practice Problems #18-19 on Page 121
Write the problem, then the answer

53. Homework, Section 3 SECTION 3 REVIEW, Page 121 Questions #20-24
Answer with complete sentences
Due tomorrow

54. Section 4: Unstable Nuclei and Radioactive Decay
National Standards:
B.2 Structure and properties of matter

55. Objectives – Section 4 REVIEW VOCABULARY:
Explain the relationship between unstable nuclei and radioactive decay.
Characterize alpha, beta, and gamma radiation in terms of mass and charge.
REVIEW VOCABULARY:
element: a pure substance that cannot be broken down into simpler substances by physical or chemical means

56. New Vocabulary radioactivity alpha particle radiation nuclear equation
nuclear reaction beta radiation
radioactive decay beta particle
alpha radiation gamma rays
Unstable atoms emit radiation to gain stability.

57. Radioactivity
Nuclear reactions can change one element into another element.
In the late 1890s, scientists noticed some substances spontaneously emitted radiation, a process they called radioactivity.
The rays and particles emitted are called radiation.
A reaction that involves a change in an atom's nucleus is called a nuclear reaction.

58. Radioactivity
Unstable nuclei lose energy by emitting radiation in a spontaneous process called radioactive decay.
Unstable radioactive elements undergo radioactive decay thus forming stable nonradioactive elements.

59. Types of Radiation
Alpha radiation is made up of positively charged particles called alpha particles.
Each alpha particle contains two protons and two neutrons and has a 2+ charge.

60. Types of Radiation
The figure shown below is a nuclear equation showing the radioactive decay of radium-226 to radon-222.
An alpha particle is equivalent to a helium-4 nucleus and is represented by 4He or
Thus, showing mass is conserved in a nuclear equation.

61. Types of Radiation
Beta radiation is radiation that has a negative charge and emits beta particles.
Each beta particle is an electron with a 1– charge.
During Beta decay, a neutron is converted to a proton and an electron. The electron is emitted and the proton stays in the nucleus.

62. Types of Radiation

63. Types of Radiation
Gamma rays are high-energy radiation with no mass and are neutral.
They usually accompany alpha and beta radiation.
Gamma rays account for most of the energy lost during radioactive decay.

64. Types of Radiation
Because gamma rays are massless, the emission of gamma rays by themselves cannot result in the formation of a new atom.

65. Types of Radiation
Atoms that contain too many or two few neutrons are unstable and lose energy through radioactive decay to form a stable nucleus.
Few exist in nature—most have already decayed to stable forms.

66. Transparency 14: Radioactive Particles

67. Questions: Mass Spectrometer – Chemical Detective

68. Homework, Section 4 SECTION 4 REVIEW, Page 124
Questions #25-29 – Answer with complete sentences
Due tomorrow
Chapter 4 Test is tentatively scheduled for Friday, October 11 .
Ch. 4 Vocab/Study Guide is due on Test Day.

69. Early Ideas About Matter
SECTION4.1
Early Ideas About Matter
Study Guide
Key Concepts
Democritus was the first person to propose the existence of atoms.
According to Democritus, atoms are solid, homogeneous, and indivisible.
Aristotle did not believe in the existence of atoms.
John Dalton’s atomic theory is based on numerous scientific experiments.

70. Defining the Atom Key Concepts
SECTION4.2
Defining the Atom
Study Guide
Key Concepts
An atom is the smallest particle of an element that maintains the properties of that element.
Electrons have a 1– charge, protons have a 1+ charge, and neutrons have no charge.
An atom consists mostly of empty space surrounding the nucleus.

71. How Atoms Differ Key Concepts
SECTION4.3
How Atoms Differ
Study Guide
Key Concepts
The atomic number of an atom is given by its number of protons. The mass number of an atom is the sum of its neutrons and protons.
atomic number = number of protons = number of electrons
mass number = atomic number + number of neutrons
Atoms of the same element with different numbers of neutrons are called isotopes.
The atomic mass of an element is a weighted average of the masses of all of its naturally occurring isotopes.

72. Unstable Nuclei and Radioactive Decay
SECTION4.4
Unstable Nuclei and Radioactive Decay
Study Guide
Key Concepts
Chemical reactions involve changes in the electrons surrounding the nucleus of an atom. Nuclear reactions involve changes in the nucleus of an atom.
There are three types of radiation: alpha (charge of 2+), beta (charge of 1–), and gamma (no charge).
The neutron-to-proton ratio of an atom’s nucleus determines its stability.