Ch. 4 Atomic Structure

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

In the nucleus of an atom, there are 18 protons and 20 neutrons. What are the atomic number and mass number of this isotope?

18 and 38

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

If an atom has 34 protons and 40 neutrons, what is its mass number?

74

According to ________, all matter was made up of four elements — earth, air, fire, and water.

Aristotle

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?

Isotope

Who provided evidence for the existence of a nucleus in an atom? a. John Dalton c. Democritus b. J. J. Thomson d. Ernest Rutherford

J. J. Thomson d. Ernest Rutherford

How did the results of J.J. Thomson's experiments change how scientists thought about atoms?

Scientist realized that atoms contained smaller subatomic particles

What did Democritus believe about matter?

They all consisted of tiny particles that could not be divided into smaller particles

What is the maximum number of electrons that an atomic orbital can contain?

Two times its amount

Which statement about electrons and atomic orbitals is NOT true? a. An electron has the same amount of energy in all orbitals. b. An orbital can contain a maximum of two electrons. c. An electron cloud represents all the orbitals in an atom. d. An atom's lowest energy level has only one orbital.

a. An electron has the same amount of energy in all orbitals.

Which of the following most accurately represents John Dalton's model of the atom? a. a tiny, solid sphere with an unpredictable mass for a given element b. a hollow sphere with a dense nucleus c. a tiny, solid sphere with a predictable mass for a given element d. a sphere that is hollow throughout

a. a tiny, solid sphere with an unpredictable mass for a given element

In an atomic model that includes a nucleus, positive charge is a. concentrated in the center of an atom. b. spread evenly throughout an atom. c. concentrated at multiple sites in an atom. d. located in the space outside the nucleus.

a. concentrated in the center of an atom.

Which subatomic particle has a negative charge? a. electron c. neutron b. alpha particle d. proton

a. electron

What do scientists use to predict the locations of electrons in atoms? a. probability c. geometry b. algebra d. ratios and proportions

a. probability

What does the electron cloud model describe? a. the most likely locations of electrons in atoms b. the precise locations of electrons in atoms c. the number of electrons in an atom d. the mass of the electrons in an atom

a. the most likely locations of electrons in atoms

According to John Dalton's observations, when elements combine in a compound, a. the ratio of their masses is always the same. b. each element contributes an equal number of atoms. c. their volumes are always equal. d. their masses are always equal.

a. the ratio of their masses is always the same.

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

Unlike Democritus, Aristotle did not believe that matter was composed of tiny, indivisible _______.

atoms

Which statement accurately represents the arrangement of electrons in Bohr's atomic model? a. Electrons vibrate in fixed locations around the nucleus. b. Electrons travel around the nucleus in fixed energy levels with energies that vary from level to level. c. Electrons travel around the nucleus in fixed energy levels with equal amounts of energy. d. Electrons travel randomly in the relatively large space outside the nucleus.

b. Electrons travel around the nucleus in fixed energy levels with energies that vary from level to level.

The Greek philosopher Democritus coined what word for a tiny piece of matter that cannot be divided? a. element c. electron b. atom d. molecule

b. atom

To find the number of neutrons in an atom, you would subtract a. mass number from atomic number. c. atomic number from electron number. b. atomic number from mass number. d. isotope number from atomic number.

b. atomic number from mass number.

J. J. Thomson's experiments provided evidence that an atom a. is the smallest particle of matter. b. contains negatively charged particles. c. has a negative charge. d. has a positive charge.

b. contains negatively charged particles.

In Niels Bohr's model of the atom, electrons move a. like balls rolling down a hill. c. like popcorn in a popcorn popper. b. like planets orbiting the sun. d. like beach balls on water waves.

b. like planets orbiting the sun.

Democritus thought that matter was made of tiny particles a. of earth, air, fire, and water. b. that could not be divided. c. that could be divided. d. that were all round and smooth.

b. that could not be divided.

What is the difference between an atom in the ground state and an atom in an excited state? a. The atom in the ground state has less energy and is less stable than the atom in an excited state. b. The atom in an excited state has one fewer electron than the atom in the ground state. c. The atom in an excited state has more energy and is less stable than the atom in the ground state. d. The atom in an excited state has one more electron than the atom in the ground state.

c. The atom in an excited state has more energy and is less stable than the atom in the ground state.

What can you assume has happened if an electron moves to a higher energy level? a. The atom has become more stable. c. The electron has gained energy. b. The electron has lost energy. d. The atom has lost an electron.

c. The electron has gained energy.

Which statement is true about oxygen-17 and oxygen-18? a. They do not have the same number of protons. b. Their atoms have an identical mass. c. They are isotopes of oxygen. d. The have the same mass number.

c. They are isotopes of oxygen.

The number of protons in one atom of an element is that element's a. mass number. c. atomic number. b. balanced charge. d. isotope.

c. atomic number

The glowing of a neon light is caused by electrons emitting energy as they a. move from lower to higher energy levels. b. collide with other electrons. c. move from higher to lower energy levels. d. collide with the nucleus.

c. move from higher to lower energy levels.

Which of the following is unique for any given element? a. the number of neutrons c. the number of protons b. the charge on the electrons d. the mass of a neutron

c. the number of protons

The moving blades of an airplane propeller provide an analogy for the electron _______ model.

cloud

John Dalton observed that elements always combine in the same ratio to form a particular ________.

compound

Which statement about subatomic particles is true? a. Protons, neutrons, and electrons all have about the same mass. b. Unlike protons or neutrons, electrons have no mass. c. Neutrons have no charge and no mass. d. An electron has far less mass than either a proton or neutron.

d. An electron has far less mass than either a proton or neutron.

How was Bohr's atomic model similar to Rutherford's model? a. It assigned energy levels to electrons. b. It described electron position in terms of the electron cloud model. c. It described how electrons gain or lose energy. d. It described a nucleus surrounded by a large volume of space.

d. It described a nucleus surrounded by a large volume of space.

Which statement best describes Rutherford's model of the atom? a. It is like an avocado with the pit representing the nucleus. b. It is like an aquarium with swimming fish representing positive charges. c. It is like a fried egg with the yolk representing the nucleus. d. It is like a huge stadium with a positively charged marble at the center.

d. It is like a huge stadium with a positively charged marble at the center.

Which statement about subatomic particles is NOT true? a. Protons and neutrons have almost the same mass. b. Protons and electrons have opposite charges. c. Unlike protons and electrons, neutrons have no charge. d. Protons and neutrons have the same charge.

d. Protons and neutrons have the same charge.

Suppose an atom has a mass number of 23. Which statement is true beyond any doubt? a. The atom has an odd number of neutrons. b. The atomic number is less than 11. c. The atom is not an isotope. d. The number of protons in the nucleus does not equal the number of neutrons.

d. The number of protons in the nucleus does not equal the number of neutrons.

Rutherford's gold foil experiment provided evidence for which of the following statements? a. Negative and positive charges are spread evenly throughout an atom. b. Alpha particles have a positive charge. c. Gold is not as dense as previously thought. d. There is a dense, positively charged mass in the center of an atom.

d. There is a dense, positively charged mass in the center of an atom.

Which of the following provides the best analogy for an electron in an atomic orbital? a. a bee moving from flower to flower in a garden b. a bird resting on a tree branch c. an ant crawling on the surface of a leaf d. a bee trying to escape from a closed jar

d. a bee trying to escape from a closed jar

In Bohr's model of the atom, ______ move in fixed orbits around the nucleus.

electrons

When an atom gains or loses energy, some of its _______ may move between energy levels.

electrons

John Dalton concluded that all the atoms of a single _______ have the same mass.

element

An atom in which an electron has moved to a higher energy level is in a(an) __________ state.

excited

When all the electrons in an atom are in orbitals with the lowest possible energy, the atom is in its ________ state.

ground

The _________ of an isotope is the sum of the number of protons and neutrons in its nucleus.

mass number

The subatomic particle that J. J. Thomson discovered has a(an) _______ charge.

negative

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? a. electrons in the gold atoms c. other alpha particles b. negative charges in the gold atoms d. nuclei in the gold atoms

negative charges in the gold atoms d. nuclei in the gold atoms

The difference between a sample of heavy water and regular water is that a hydrogen atom in heavy water has an extra ________.

neutron

Protons and _____ are found in the nucleus of an atom.

neutrons

The nuclei of isotopes contain different numbers of ________.

neutrons

In Rutherford's gold foil experiment, shown in Figure 4-1, alpha particles that bounce straight back from the foil have struck ________ in the gold atoms.

nucleus

The results of Rutherford's gold foil experiment demonstrated that the _______ occupies a very small amount of the total space inside an atom.

nucleus

If element Q has 11 protons, its atomic _____ is 11.

number

The region in which an electron is most likely to be found is called a(an) ________.

orbital

Neutrons and _______ have almost the same mass.

protons