Physical Science - Ch. 4 comprehension check study practice
57. If an atom of an element has a mass number of 32 and 20 neutrons in its nucleus, what is the atomic number of the element?
12
64. What is the maximum number of electrons that an atomic orbital can contain?
2
If 2 grams of element X combine with 4 grams of element Y to form compound XY, how many grams of element Y would combine with 14 grams of X to form the same compound?
28 grams
58. If an atom of tin has a mass number of 118 and an atomic number of 50, how many neutrons are in its nucleus?
68
55. If an atom has 34 protons and 40 neutrons, what is its mass number?
74
John Dalton's atomic theory
All elements are composed of atoms. All atoms of the same element have the same mass. A compound contains atoms of more than one element.
67. A sample of calcium contains calcium-40, calcium-44, calcium-42, calcium-48, calcium-43, and calcium-46 atoms. Explain why these atoms can have different mass numbers but must have the same atomic number.
All the atoms of an element have the same atomic number because the atomic number equals the number of protons in an atom. If one of the atoms had a different number of protons, the atom would not be a calcium atom. The mass number can vary because it is the sum of the protons and neutrons, and isotopes of an element can have different numbers of neutrons.
True statement about subatomic particles
An electron has far less mass than either a proton or neutron.
statement about electrons and atomic orbitals that is NOT true
An electron has the same amount of energy in all orbitals.
69. What is the difference between an orbital and the electron cloud?
An orbital is a region of space around the nucleus where an electron is likely to be found. The electron cloud is a visual model that represents all the orbitals in an atom.
31. According to ____________________, all matter was made up of four elements — earth, air, fire, and water.
Aristotle
statement that accurately represents the arrangement of electrons in Bohr's atomic model
Electrons travel around the nucleus in fixed energy levels with energies that vary from level to level.
How was Bohr's atomic model similar to Rutherford's model?
It described a nucleus surrounded by a large volume of space.
62. What did Bohr's model of the atom do that Rutherford's model did not?
It focused on electrons.
statement that describes Rutherford's model of the atom
It is like a huge stadium with a positively charged marble at the center.
63. How does the electron cloud model of the atom represent the locations of electrons in atoms?
It provides a visual model of the most likely locations of electrons in an atom.
68. Why is Bohr's model of the atom often called the planetary model?
It represents electrons as moving in fixed orbits around the nucleus like planets moving in orbits around a sun.
This statement about subatomic particles is NOT true?
Protons and neutrons have the same charge.
Who provided evidence for the existence of a nucleus in an atom?
Rutherford (along with his colleague [Geiger] and student [ Marsden])
61. What can scientists measure to provide evidence that electrons can move from one energy level to another?
Scientists can measure the wavelengths of light energy released when the electrons return to a lower energy level.
52. How did the results of J.J. Thomson's experiments change how scientists thought about atoms?
Scientists realized that atoms contained smaller subatomic particles.
What is the difference between an atom in the ground state and an atom in an excited state?
The atom in an excited state has more energy and is less stable than the atom in the ground state.
65. How does the state of atoms in a neon light change when light is emitted?
The atoms return from an excited state to the ground state.
What can you assume has happened if an electron moves to a higher energy level?
The electron has gained energy.
Suppose an atom has a mass number of 23. What is true beyond any doubt?
The number of protons in the nucleus does not equal the number of neutrons.
53. What did Rutherford conclude about the location of positive charge in an atom?
The positive charge was concentrated in the nucleus of an atom.
79. Inferring Why do you think the proton was discovered before the neutron? (Hint: Consider the properties of protons and neutrons.)
The proton has a positive charge, but the neutron has no charge. It was easier to detect the existence of a charged particle because its path could be deflected by another charged object.
9. Rutherford's gold foil experiment provided evidence for this statement.
There is a dense, positively charged mass in the center of an atom.
True statement about oxygen-17 and oxygen-18
They are isotopes of oxygen.
66. Why did Rutherford propose a new model of the atom after seeing the results of the gold foil experiment?
Thomson's model no longer explained all of the available evidence. In Thomson's model, for example, positive charge was spread evenly throughout the atom. Rutherford had concluded that the positive charge of an atom was concentrated in the center of the atom.
70. Explain what the colors in a fireworks display reveal about the movement of electrons in atoms.
When fireworks explode, the heat produced by the explosions causes some electrons in atoms to move to higher energy levels. When the electrons return to lower energy levels, some of the energy is released as visible light. The colors var because each element has a different set of energy levels.
Which of the following provides the best analogy for an electron in an atomic orbital?
a bee trying to escape from a closed jar
accurately represents John Dalton's model of the atom
a tiny, solid sphere with a predictable mass for a given element
51. What did Democritus believe about matter?
all matter consisted of tiny particles that could not be divided into smaller particles
37. In Rutherford's gold foil experiment, some of the _________________________ aimed at gold atoms bounced back, suggesting that a solid mass was at the center of the atom.
alpha particles
The Greek philosopher Democritus coined what word for a tiny piece of matter that cannot be divided?
atom
56. What scientific word comes from a Greek word meaning "uncut"? Which Greek philosopher first used the word to describe matter?
atom; Democritus
The number of protons in one atom of an element is that element's
atomic #
60. In the nucleus of an atom, there are 18 protons and 20 neutrons. What are the atomic number and mass number of this isotope?
atomic # = 18; mass number = 38
To find the number of neutrons in an atom, you would subtract
atomic number from mass number.
32. Unlike Democritus, Aristotle did not believe that matter was composed of tiny, indivisible ____________________.
atoms
47. The moving blades of an airplane propeller provide an analogy for the electron ____________________ model.
cloud
34. John Dalton observed that elements always combine in the same ratio to form a particular ____________________.
compount
In an atomic model that includes a nucleus, positive charge is
concentrated in the center of an atom.
J. J. Thomson's experiments provided evidence that an atom
contains negatively charged particles.
Democritus though that matter was made of tiny particles that could/could not (choose one) be divided.
could not
54. Which of the three subatomic particles—proton, electron, or neutron—has the least mass?
electron
Which subatomic particle has a negative charge?
electron
45. In Bohr's model of the atom, ____________________ move in fixed orbits around the nucleus.
electrons
46. When an atom gains or loses energy, some of its ____________________ may move between energy levels.
electrons
33. John Dalton concluded that all the atoms of a single ____________________ have the same mass.
element
50. An atom in which an electron has moved to a higher energy level is in a(an) ____________________ state.
excited
49. When all the electrons in an atom are in orbitals with the lowest possible energy, the atom is in its ____________________ state.
ground
59. Most calcium atoms have an atomic number of 20 and a mass number of 40, but some calcium atoms have a mass number of 48. What word could you use to describe these two kinds of calcium atoms?
isotopes
In Niels Bohr's model of the atom, electrons move
like planets orbiting the sun.
43. The ____________________ of an isotope is the sum of the number of protons and neutrons in its nucleus.
mass number
The glowing of a neon light is caused by electrons emitting energy as they
move from higher to lower energy levels.
35. The subatomic particle that J. J. Thomson discovered has a(an) ____________________ charge.
negative
44. The difference between a sample of heavy water and regular water is that a hydrogen atom in heavy water has an extra ____________________.
neutron
39. Protons and ____________________ are found in the nucleus of an atom.
neutrons
42. The nuclei of isotopes contain different numbers of ____________________.
neutrons
36. In Rutherford's gold foil experiment, shown in the figure on the other side of the flash card, alpha particles that bounce straight back from the foil have struck ____________________ in the gold atoms.
nuclei
The diagram in Figure 4-1 shows the results of Rutherford's gold foil experiment. What caused some of the alpha particles to bounce straight back from the gold foil?
nuclei in the gold atoms
38. The results of Rutherford's gold foil experiment demonstrated that the ____________________ occupies a very small amount of the total space inside an atom.
nucleus
41. If element Q has 11 protons, its atomic ____________________ is 11.
number
48. The region in which an electron is most likely to be found is called a(an) ____________________.
orbital
What do scientists use to predict the locations of electrons in atoms?
probability
40. Neutrons and ____________________ have almost the same mass.
protons
unique for any given element
the # of protons
What does the electron cloud model describe?
the most likely locations of electrons in atoms
According to John Dalton's observations, when elements combine in a compound,
the ratio of their masses is always the same.
