Physical Science; Ch. 4 Test

Multiple Choice

Identify the choice that best completes the statement or answers the question.

____ 1. Which of the following scientists inferred that an atom’s positive charge must be clustered in the nucleus?

a.	Niels Bohr
b.	John Dalton
c.	Ernest Rutherford
d.	J.J. Thomson

____ 2. Which particles in atoms have a negative electric charge?

a.	electrons
b.	protons
c.	neutrons
d.	nuclei

____ 3. In an atom, the number of protons equals the number of

a.	nuclei.
b.	electrons.
c.	neutrons.
d.	isotopes.

____ 4. Mendeleev created the first periodic table by arranging elements in order of

a.	decreasing atomic mass.
b.	increasing atomic mass.
c.	increasing atomic number.
d.	increasing melting points and densities.

____ 5. How did chemists change Mendeleev’s periodic table in the early 1900s?

a.	They included chemical properties such as bonding power.
b.	They included physical properties such as melting point and density.
c.	They used atomic mass instead of atomic number to organize the elements.
d.	They used atomic number instead of atomic mass to organize the elements.

____ 6. What prediction did Mendeleev make that came true less than 20 years later?

a.	He predicted the atomic numbers of unknown elements.
b.	He predicted that a total of 112 elements would be discovered.
c.	He said that three new elements would be discovered, and he described their properties.
d.	He said that the periodic table would be developed into 18 families.

____ 7. The elements in a column of the periodic table

a.	have similar properties.
b.	are in the same period.
c.	have the same atomic mass.
d.	have very similar chemical symbols.

____ 8. What information in the periodic table indicates the number of protons in an atom?

a.	the position of the element in its column
b.	the element’s chemical symbol
c.	the element’s atomic number
d.	the element’s atomic mass

____ 9. Most metals are NOT

a.	ductile.
b.	good conductors of heat and electricity.
c.	liquid at room temperature.
d.	malleable.

____ 10. In general, which of the following statements about metals is true?

a.	Metals need to be stored in sealed containers for safety.
b.	Metals show a wide range of chemical properties.
c.	Metals are highly reactive substances.
d.	Metals do not react with oxygen.

____ 11. Which group contains the most elements?

a.	semimetals
b.	nonmetals
c.	metals
d.	transition elements

____ 12. A material is said to be ductile if it

a.	can be pulled out, or drawn, into a long wire.
b.	can be hammered or rolled into flat sheets and other shapes.
c.	can transfer heat or electricity to another material.
d.	is a mixture of a metal with at least one other element.

____ 13. In the periodic table, the most reactive metals are found

a.	in Group 1, the first column on the left.
b.	in Period 1, the first row across the top.
c.	in Groups 13 through 16 in the center.
d.	in Periods 6 and 7 at the bottom.

____ 14. The two most common alkaline earth metals are

a.	copper and zinc.
b.	iron and silver.
c.	sodium and potassium.
d.	calcium and magnesium.

____ 15. Which of the following statements about transition metals is true?

a.	They are never found uncombined in nature.
b.	They include familiar metals such as gold, silver, copper, and nickel.
c.	They are so soft that they can be cut with an ordinary knife.
d.	They are the most reactive of all the types of metals.

____ 16. To make most synthetic elements, scientists use powerful machines called

a.	semiconductors.
b.	particle accelerators.
c.	supernovae.
d.	nebulas.

____ 17. Why would it probably be very difficult to determine the chemical and physical properties of a newly discovered synthetic element?

a.	The element would not fit in the periodic table.
b.	The element’s nuclei would break apart very quickly.
c.	The element would combine the properties of the nuclei from which it was made.
d.	The element would lack many properties of ordinary elements.

____ 18. Which property of bromine could you NOT predict based on the fact that it is a nonmetal in the halogen family?

a.	highly reactive
b.	poor conductor of electricity
c.	liquid at room temperature
d.	poor conductor of heat

____ 19. The elements that do not ordinarily form compounds are

a.	elements in the carbon family.
b.	metals.
c.	halogens.
d.	inert gases.

____ 20. Fluorine, chlorine, bromine, and iodine are part of a family called

a.	inert gases.
b.	semimetals.
c.	halogens.
d.	alkali metals.

____ 21. Which group of elements shares characteristics with both metals and nonmetals?

a.	salts
b.	semimetals
c.	halogens
d.	lanthanides

____ 22. In 1896, the French scientist Henri Becquerel discovered

a.	light-emitting polymers.
b.	a process to turn natural rubber into a hard, stretchable polymer.
c.	radioactive decay.
d.	how to make alloys.

____ 23. During radioactive decay, atomic nuclei of unstable isotopes

a.	give off nuclear radiation.
b.	are broken down by radioactive bacteria.
c.	form chemical bonds.
d.	are unchanged.

____ 24. A piece of paper will provide protection from

a.	alpha radiation.
b.	beta radiation.
c.	gamma radiation.
d.	gamma rays.

____ 25. The reason radioactive isotopes can be followed through the steps of a chemical reaction or industrial process is that they

a.	are stable.
b.	give off radiation.
c.	do not react chemically as nonradioactive isotopes do.
d.	do not decay.

____ 26. In radiation therapy,

a.	isotopes are traced through a chemical reaction.
b.	unhealthy human cells are destroyed.
c.	radioactive isotopes are used as fuel.
d.	weak spots in water pipes are found.

____ 27. Radioactive isotopes called ____ can be used to detect some medical problems.

a.	beta particles
b.	tracers
c.	gamma radiation
d.	alpha particles

____ 28. The most useful property of semimetals is their

a.	ability to be pulled out into long wires.
b.	softness and malleability.
c.	tendency to be unreactive.
d.	varying ability to conduct electricitic current.

____ 29. A carbon-14 nucleus decays to form a nitrogen-14 nucleus. What kind of nuclear radiation is released by this process?

a.	alpha particles
b.	beta particles
c.	gamma rays
d.	light rays

____ 30. Which form of nuclear radiation consists of high-energy waves similar to X-rays?

a.	alpha particles
b.	beta particles
c.	gamma rays
d.	isotopes

Modified True/False

Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.

____ 31. Protons have no charge; they are neutral. _________________________

____ 32. The modern periodic table is organized according to atomic mass. _________________________

____ 33. The horizontal rows in the periodic table are known as groups. _________________________

____ 34. The elements in a group of the periodic table have similar characteristics. _________________________

____ 35. Describing a metal as malleable means that it can be pounded into a new shape. _________________________

____ 36. The most chemically reactive metals are in Group 1 of the periodic table. _________________________

____ 37. In general, the physical properties of nonmetals are similar to the properties of metals. _________________________

____ 38. Atoms of the halogen family of elements typically gain two electrons when they react. _________________________

____ 39. A radioactive isotope that can be followed through the steps of a chemical reaction is a(n) indicator. _________________________

____ 40. Positively charged particles in an atom’s nucleus are called neutrons.

Completion

Complete each statement.

41. The ____________________ is the very small center core of an atom.

42. Part of ________________ atomic theory was atoms cannot be created or destroyed in any chemical change, only rearranged.

43. The property of an element that indicates the number of protons in its atoms is the ____________________.

44. Mendeleev discovered that periodic patterns appeared when he arranged the elements in order of increasing ____________________.

45. In the 1800s, Dmitri Mendeleev organized the first truly useful ____________________.

46. A column of elements in the periodic table is called a group, or ____________________.

47. Each element is given a specific _________________________ that usually consists of one or two letters.

48. Elements that easily transmit electricity and heat display the property known as ____________________.

49. Most metals are in the ____________________ state at room temperature.

50. The chemical reactivity of metals tends to ____________________ from left to right across the periodic table.

51. Elements with atomic numbers higher than 92 are not found naturally on Earth, so they must be made, or ____________________, by crashing nuclear particles into each other.

52. Elements that form diatomic molecules, or molecules of two atoms each, are commonly found on the ____________________ side of the periodic table.

53. Nonmetals are ____________________ conductors of heat and electricity.

54. At room temperature, all the semimetals are solids, while most nonmetals are ____________________.

55. A substance that will conduct electricity only under certain conditions is called a(n) ____________________.

56. A(n) ____________________ particle is positively charged and consists of two protons and neutrons.

57. A(n) _________________________ is a fast-moving electron given off by a nucleus during radioactive decay.

58. Becquerel observed that a photographic plate developed an image of a uranium sample even though the plate was wrapped in paper. He hypothesized that the uranium must be emitting energy in the form of _________________________.

59. The spontaneous emission of radiation by an unstable atomic nucleus was named ____________________ by Marie Curie

60. An electron’s movement is related to its ____________________, or the specific amount of energy it has.

Short Answer

Use the diagram to answer each question.

Atoms of Some Common Elements

Element	Atomic Number	Mass Number	Protons	Neutrons	Electrons
Sodium	11	?	11	12	?
Magnesium	12	24	12	?	12
Aluminum	?	27	13	14	13
Phosphorus	15	31	?	16	15

61. What is the mass number of sodium?

62. What is the total number of electrons in an atom of sodium?

63. How many neutrons are in an atom of magnesium?

64. What is the atomic number of aluminum?

65. How many protons are in an atom of phosphorus?

66. The element silicon has been omitted from this table. It appears in Period 3 of the periodic table between aluminum and phosphorus. Given that information, which of the five columns in the chart could you fill in for silicon?

Use the diagram to answer each question.

67. Which group of elements reacts violently with elements from Group 1?

68. If a metal reacts violently with water, in which group is it likely to be found?

69. What name is given to the elements in Groups 3 through 12? How do their properties tend to compare with the elements to the left and right of these groups?

70. Locate the box in Group 18 in the fourth period. Predict the state of matter and the chemical reactivity of the element that belongs in that box.

71. Most of the elements that form a zigzag line in the periodic table belong to one major group. What is that group, and what kinds of properties do its elements tend to have?

72. What are the two most important alkali metals? Why are they so important?

Essay

73. What contribution did the Russian chemist Dmitri Mendeleev make to chemistry? What was he able to do to show the value of his contribution?

74. Explain why the atomic mass of an element is usually not given as a whole number even though each individual atom of the element has a whole number of protons and neutrons.

75. Compare the properties of metals and nonmetals.

76. Metals show a wide range of chemical behavior. Give examples of that variation by describing some common properties of calcium, gold, iron, and sodium.

77. Group 17 is called the halogen family, and the group to its right is called the inert gases. How are these elements alike and how are they different?

78. Compare and contrast types of radioactive decay involving alpha particles, beta particles, and gamma radiation.

79. Give several examples of how radioactive isotopes are useful.

80. Explain the general process by which new elements are synthesized.

Physical Science; Ch. 4 Test

Answer Section

MULTIPLE CHOICE

1. ANS: C PTS: 1 DIF: L2

OBJ: CaPS.4.1.1 Describe how atomic theory differs from Democritus's idea of the atom.

STA: S 8.3.a BLM: comprehension

2. ANS: A PTS: 1 DIF: L1

OBJ: CaPS.4.1.1 Describe how atomic theory differs from Democritus's idea of the atom.

STA: S 8.3.a BLM: knowledge

3. ANS: B PTS: 1 DIF: L1

OBJ: CaPS.4.1.2 Describe the modern model of the atom. STA: S 8.3.a

BLM: knowledge

4. ANS: B PTS: 1 DIF: L2

OBJ: CaPS.4.2.1 Explain how Mendeleev discovered the pattern that led to the periodic table.

STA: S 8.7 BLM: comprehension

5. ANS: D PTS: 1 DIF: L2

OBJ: CaPS.4.2.1 Explain how Mendeleev discovered the pattern that led to the periodic table.

STA: S 8.7.b BLM: comprehension

6. ANS: C PTS: 1 DIF: L2

OBJ: CaPS.4.2.1 Explain how Mendeleev discovered the pattern that led to the periodic table.

STA: S 8.7.a BLM: comprehension

7. ANS: A PTS: 1 DIF: L1

OBJ: CaPS.4.2.2 Describe how elements are organized in the modern periodic table.

STA: S 8.7.a BLM: knowledge

8. ANS: C PTS: 1 DIF: L2

OBJ: CaPS.4.2.2 Describe how elements are organized in the modern periodic table.

STA: S 8.3.a BLM: comprehension

9. ANS: C PTS: 1 DIF: L2

OBJ: CaPS.4.3.1 List the physical properties of metals. STA: S 8.7.c

BLM: comprehension

10. ANS: B PTS: 1 DIF: L2

OBJ: CaPS.4.3.1 List the physical properties of metals. STA: S 8.7.c

BLM: comprehension

11. ANS: C PTS: 1 DIF: L2

OBJ: CaPS.4.3.1 List the physical properties of metals. STA: S 8.7.a | S 8.7.c

BLM: application

12. ANS: A PTS: 1 DIF: L1

OBJ: CaPS.4.3.1 List the physical properties of metals. STA: S 8.7.c

BLM: knowledge

13. ANS: A PTS: 1 DIF: L2

OBJ: CaPS.4.3.2 Explain how the reactivity of metals changes across the periodic table.

STA: S 8.3.a | S 8.7.a BLM: comprehension

14. ANS: D PTS: 1 DIF: L1

OBJ: CaPS.4.3.2 Explain how the reactivity of metals changes across the periodic table.

STA: S 8.7.a BLM: knowledge

15. ANS: B PTS: 1 DIF: L2

OBJ: CaPS.4.3.2 Explain how the reactivity of metals changes across the periodic table.

STA: S 8.7.a BLM: comprehension

16. ANS: B PTS: 1 DIF: L2

OBJ: CaPS.4.3.3 Explain how synthetic elements are produced. STA: S 8.3

BLM: comprehension

17. ANS: B PTS: 1 DIF: L3

OBJ: CaPS.4.3.3 Explain how synthetic elements are produced. STA: S 8.7

BLM: synthesis

18. ANS: C PTS: 1 DIF: L2

OBJ: CaPS.4.4.1 Describe the properties of nonmetals and inert gases.

STA: S 8.7.c BLM: application

19. ANS: D PTS: 1 DIF: L2

OBJ: CaPS.4.4.1 Describe the properties of nonmetals and inert gases.

STA: S 8.3.f | S 8.7.a BLM: comprehension

20. ANS: C PTS: 1 DIF: L2

OBJ: CaPS.4.4.1 Describe the properties of nonmetals and inert gases.

STA: S 8.3.f | S 8.7.a BLM: application

21. ANS: B PTS: 1 DIF: L1

OBJ: CaPS.4.4.2 List the uses of semimetals. STA: S 8.3.f | S 8.7.a

BLM: knowledge

22. ANS: C PTS: 1 DIF: L1

OBJ: CaPS.4.5.1 Explain how radioactivity was discovered. STA: S 8.3

BLM: knowledge

23. ANS: A PTS: 1 DIF: L2

OBJ: CaPS.4.5.2 Identify the types of particles and energy that radioactive decay can produce.

STA: S 8.7.b BLM: comprehension

24. ANS: A PTS: 1 DIF: L2

OBJ: CaPS.4.5.2 Identify the types of particles and energy that radioactive decay can produce.

STA: S 8.7.b BLM: comprehension

25. ANS: B PTS: 1 DIF: L2

OBJ: CaPS.4.5.3 Describe how radioactive isotopes are useful. STA: S 8.7.b

BLM: comprehension

26. ANS: B PTS: 1 DIF: L1

OBJ: CaPS.4.5.3 Describe how radioactive isotopes are useful. STA: S 8.7.b

BLM: knowledge

27. ANS: B PTS: 1 DIF: L2

OBJ: CaPS.4.5.3 Describe how radioactive isotopes are useful. STA: S 8.7.b

BLM: comprehension

28. ANS: D PTS: 1 DIF: L2

OBJ: CaPS.4.4.2 List the uses of semimetals. STA: S 8.7.c

BLM: comprehension

29. ANS: C PTS: 1 DIF: L3

OBJ: CaPS.4.5.2 Identify the types of particles and energy that radioactive decay can produce.

STA: S 8.7.b BLM: analysis

30. ANS: C PTS: 1 DIF: L1

OBJ: CaPS.4.5.2 Identify the types of particles and energy that radioactive decay can produce.

STA: S 8.7.b BLM: knowledge

MODIFIED TRUE/FALSE

31. ANS: F, Neutrons

PTS: 1 DIF: L2

OBJ: CaPS.4.1.2 Describe the modern model of the atom. STA: S 8.3.a

BLM: comprehension

32. ANS: F, atomic number

PTS: 1 DIF: L1

OBJ: CaPS.4.2.1 Explain how Mendeleev discovered the pattern that led to the periodic table.

STA: S 8.3.f | S 8.7.a BLM: knowledge

33. ANS: F, periods

PTS: 1 DIF: L1

OBJ: CaPS.4.2.2 Describe how elements are organized in the modern periodic table.

STA: S 8.3.f | S 8.7.a BLM: knowledge

34. ANS: T PTS: 1 DIF: L2

OBJ: CaPS.4.2.2 Describe how elements are organized in the modern periodic table.

STA: S 8.3.f | S 8.7.a BLM: comprehension

35. ANS: T PTS: 1 DIF: L1

OBJ: CaPS.4.3.1 List the physical properties of metals. STA: S 8.7.c

BLM: knowledge

36. ANS: T PTS: 1 DIF: L2

OBJ: CaPS.4.3.2 Explain how the reactivity of metals changes across the periodic table.

STA: S 8.7.a | S 8.7.c BLM: comprehension

37. ANS: F, different from

PTS: 1 DIF: L1

OBJ: CaPS.4.4.1 Describe the properties of nonmetals and inert gases.

STA: S 8.7.c BLM: knowledge

38. ANS: F, one electron

PTS: 1 DIF: L1

OBJ: CaPS.4.4.1 Describe the properties of nonmetals and inert gases.

STA: S 8.7.a BLM: knowledge

39. ANS: F, tracer

PTS: 1 DIF: L1

OBJ: CaPS.4.5.3 Describe how radioactive isotopes are useful. STA: S 8.7.b

BLM: knowledge

40. ANS: F, protons

PTS: 1 DIF: L1

OBJ: CaPS.4.1.1 Describe how atomic theory differs from Democritus's idea of the atom.

STA: S 8.3.a BLM: knowledge

COMPLETION

41. ANS: nucleus

PTS: 1 DIF: L1

OBJ: CaPS.4.1.1 Describe how atomic theory differs from Democritus's idea of the atom.

STA: S 8.3.a BLM: knowledge

42. ANS: Dalton’s

PTS: 1 DIF: L2

OBJ: CaPS.4.1.1 Describe how atomic theory differs from Democritus's idea of the atom.

STA: S 8.3 BLM: comprehension

43. ANS: atomic number

PTS: 1 DIF: L2

OBJ: CaPS.4.1.2 Describe the modern model of the atom. STA: S 8.7.b

BLM: comprehension

44. ANS: atomic mass

PTS: 1 DIF: L2

OBJ: CaPS.4.2.1 Explain how Mendeleev discovered the pattern that led to the periodic table.

STA: S 8.7 BLM: comprehension

45. ANS: periodic table

PTS: 1 DIF: L1

OBJ: CaPS.4.2.1 Explain how Mendeleev discovered the pattern that led to the periodic table.

STA: S 8.7 BLM: knowledge

46. ANS: family

PTS: 1 DIF: L1

OBJ: CaPS.4.2.2 Describe how elements are organized in the modern periodic table.

STA: S 8.7.a BLM: knowledge

47. ANS: chemical symbol

PTS: 1 DIF: L2

OBJ: CaPS.4.2.2 Describe how elements are organized in the modern periodic table.

STA: S 8.7.a BLM: comprehension

48. ANS: conductivity

PTS: 1 DIF: L1

OBJ: CaPS.4.3.1 List the physical properties of metals. STA: S 8.7.c

BLM: knowledge

49. ANS: solid

PTS: 1 DIF: L1

OBJ: CaPS.4.3.1 List the physical properties of metals. STA: S 8.7.c

BLM: knowledge

50. ANS: decrease

PTS: 1 DIF: L1

OBJ: CaPS.4.3.2 Explain how the reactivity of metals changes across the periodic table.

STA: S 8.7.a BLM: knowledge

51. ANS: synthesized

PTS: 1 DIF: L2

OBJ: CaPS.4.3.3 Explain how synthetic elements are produced. STA: S 8.7

BLM: comprehension

52. ANS: right

PTS: 1 DIF: L2

OBJ: CaPS.4.4.1 Describe the properties of nonmetals and inert gases.

STA: S 8.7.a BLM: application

53. ANS: poor

PTS: 1 DIF: L1

OBJ: CaPS.4.4.1 Describe the properties of nonmetals and inert gases.

STA: S 8.7.c BLM: knowledge

54. ANS: gases

PTS: 1 DIF: L2

OBJ: CaPS.4.4.1 Describe the properties of nonmetals and inert gases.

STA: S 8.7.c BLM: comprehension

55. ANS: semiconductor

PTS: 1 DIF: L1 OBJ: CaPS.4.4.2 List the uses of semimetals.

STA: S 8.7.c BLM: knowledge

56. ANS: alpha

PTS: 1 DIF: L1

OBJ: CaPS.4.5.2 Identify the types of particles and energy that radioactive decay can produce.

STA: S 8.3.a BLM: knowledge

57. ANS: beta particle

PTS: 1 DIF: L1

OBJ: CaPS.4.5.2 Identify the types of particles and energy that radioactive decay can produce.

STA: S 8.7.b BLM: knowledge

58. ANS: radiation

PTS: 1 DIF: L2

OBJ: CaPS.4.5.1 Explain how radioactivity was discovered. STA: S 8.3

BLM: comprehension

59. ANS: radioactivity

PTS: 1 DIF: L1

OBJ: CaPS.4.5.1 Explain how radioactivity was discovered. STA: S 8.7

BLM: knowledge

60. ANS: energy level

PTS: 1 DIF: L1

OBJ: CaPS.4.1.1 Describe how atomic theory differs from Democritus's idea of the atom.

STA: S 8.3.a BLM: knowledge

SHORT ANSWER

61. ANS:

23

PTS: 1 DIF: L2

OBJ: CaPS.4.1.2 Describe the modern model of the atom. STA: S 8.3.a

BLM: analysis

62. ANS:

11

PTS: 1 DIF: L2

OBJ: CaPS.4.1.2 Describe the modern model of the atom. STA: S 8.3.a

BLM: analysis

63. ANS:

12

PTS: 1 DIF: L2

OBJ: CaPS.4.1.2 Describe the modern model of the atom. STA: S 8.3.a

BLM: analysis

64. ANS:

13

PTS: 1 DIF: L2

OBJ: CaPS.4.1.2 Describe the modern model of the atom. STA: S 8.7.a

BLM: analysis

65. ANS:

15

PTS: 1 DIF: L2

OBJ: CaPS.4.1.2 Describe the modern model of the atom. STA: S 8.3.a

BLM: analysis

66. ANS:

Silicon’s atomic number is 14, and a silicon atom has 14 protons and 14 electrons. You cannot determine the number of neutrons or the mass number.

PTS: 1 DIF: L3

OBJ: CaPS.4.2.2 Describe how elements are organized in the modern periodic table.

STA: S 8.7.a BLM: synthesis

67. ANS:

Group 17

PTS: 1 DIF: L2

OBJ: CaPS.4.2.2 Describe how elements are organized in the modern periodic table.

STA: S 8.7.a BLM: analysis

68. ANS:

Group 1

PTS: 1 DIF: L2

OBJ: CaPS.4.2.2 Describe how elements are organized in the modern periodic table.

STA: S 8.3.f | S 8.7.a BLM: analysis

69. ANS:

Transition metals. They are less reactive than the metals in Groups 1 and 2 to their left; they tend to be more reactive than the metals to their right.

PTS: 1 DIF: L3

OBJ: CaPS.4.3.2 Explain how the reactivity of metals changes across the periodic table.

STA: S 8.7.a BLM: synthesis

70. ANS:

The element is a gas, one of the inert gases. It does not ordinarily react with other elements to form compounds.

PTS: 1 DIF: L3

OBJ: CaPS.4.4.1 Describe the properties of nonmetals and inert gases.

STA: S 8.7.a BLM: synthesis

71. ANS:

Semimetals. Semimetals have some properties of metals and some properties of nonmetals.

PTS: 1 DIF: L2 OBJ: CaPS.4.4.2 List the uses of semimetals.

STA: S 8.3.f | S 8.7.a BLM: analysis

72. ANS:

Potassium and sodium. Sodium compounds are found in large amounts in seawater and salt beds. Both sodium and potassium are found in your diet and are important for life.

PTS: 1 DIF: L2

OBJ: CaPS.4.3.2 Explain how the reactivity of metals changes across the periodic table.

STA: S 8.6.b BLM: application

ESSAY

73. ANS:

Mendeleev organized the first useful periodic table. He arranged the elements in order of increasing atomic mass and grouped them according to properties that repeated in patterns. By using this periodic arrangement, Mendeleev was able to predict the properties of several elements that had not yet been discovered.

PTS: 1 DIF: L2

OBJ: CaPS.4.2.1 Explain how Mendeleev discovered the pattern that led to the periodic table.

STA: S 8.7 BLM: comprehension

74. ANS:

All atoms of a given element have the same number of protons, but those atoms may have different numbers of neutrons. That means that the masses of individual atoms are not necessarily the same. The atomic mass for the element is the average mass of all the different atoms. That average is not a whole number.

PTS: 1 DIF: L3

OBJ: CaPS.4.2.2 Describe how elements are organized in the modern periodic table.

STA: S 8.7.b BLM: synthesis

75. ANS:

Metals are generally solid at room temperature; are shiny, malleable, and ductile; and are good conductors. Nonmetals are generally gases at room temperature. Solid nonmetals are usually dull and brittle, and are poor conductors. The properties of metals are generally the opposite of the properties of nonmetals.

PTS: 1 DIF: L2

OBJ: CaPS.4.3.1 List the physical properties of metals. | CaPS.4.4.1 Describe the properties of nonmetals and inert gases. STA: S 8.7.a | S 8.7.c

BLM: analysis

76. ANS:

Sodium is one of the most chemically reactive metals; it can react explosively with air or water if not stored properly. Calcium is less reactive than sodium, but it is more reactive than most metals. In nature, sodium and calcium are always found in compounds, and never as elements. Iron also reacts with oxygen, but it does so over a period of time; unprotected iron will gradually turn to rust, a compound of iron and oxygen. Gold is extremely unreactive with air and water; in nature, metallic gold can remain in its elemental form indefinitely.

PTS: 1 DIF: L2

OBJ: CaPS.4.3.2 Explain how the reactivity of metals changes across the periodic table.

STA: S 8.7.a | S 8.7.c BLM: application

77. ANS:

Both groups are nonmetals. All of Group 18 and all but one element in Group 17 are gases under ordinary conditions. However, their chemical behavior is very different. The atoms of halogens easily gain one electron, making them extremely reactive. The inert gases do not ordinarily gain, lose, or share electrons, making them chemically unreactive.

PTS: 1 DIF: L3

OBJ: CaPS.4.4.1 Describe the properties of nonmetals and inert gases.

STA: S 8.7.a | S 8.7.c BLM: analysis

78. ANS:

During alpha decay, an alpha particle made of two protons and two neutrons is released. The atomic number decreases by two and the mass number decreases by four. In beta decay, a neutron decays, giving off a proton and a beta particle, or electron. The proton remains in the nucleus and the beta particle is released. The atomic number increases by one and the mass number stays the same. Gamma radiation, a form of high-energy waves, almost always accompanies alpha and beta decay. Gamma radiation is the most penetrating form of radiation, beta particles are less penetrating, and alpha particles are the least penetrating.

PTS: 1 DIF: L2

OBJ: CaPS.4.5.2 Identify the types of particles and energy that radioactive decay can produce.

STA: S 8.7.b BLM: analysis

79. ANS:

Student examples may vary. Possible answers: Radioactive isotopes are used as tracers in chemical reactions and industrial processes. For example, a tracer can be used to find out how a plant uses a specific element or whether or not leaks have formed in metal pipes. Radioactive isotopes are also used to find out about and treat medical problems. Radioactive isotopes are useful because they give off radiation that can be detected.

PTS: 1 DIF: L2

OBJ: CaPS.4.5.3 Describe how radioactive isotopes are useful. STA: S 8.7.b

BLM: application

80. ANS:

Scientists make synthetic elements by forcing nuclear particles to crash into one another. For example, plutonium is made by bombarding nuclei of uranium-238 with neutrons in a nuclear reactor. To make even heavier elements (with atomic numbers above 95), scientists use powerful machines called particle accelerators. Particle accelerators move atomic nuclei faster and faster until they have reached very high speeds. If these fast-moving nuclei crash into the nuclei of other elements with enough energy, the particles can sometimes combine into a single nucleus.

PTS: 1 DIF: L2

OBJ: CaPS.4.3.3 Explain how synthetic elements are produced. STA: S 8.7

BLM: comprehension