Module 3 Chem test
In the late-1800s experiments in which scientists began researching radioactivity,
three different types of radiation were detected. radiation was directed between two electrically charged plates. electrically neutral radiation was not deflected towards either plate. negatively charged radiation was deflected towards the positively charged plate.
Neutron in amu
1.008665 amu
The mass and charge of a beta particle are, respectively, ______.
1/1840 amu and 1-
Alpha radiation consists of alpha particles, which have a charge of _____ and a mas of ____ amu
2+, 4
Beryllium has an atomic number of 4. Therefore, a beryllium atom has ____ protons and ____ electrons
4, 4
The mass of an electron is ______.
9.1 × 10^-28 g
Which is a high-speed electron with a 1- charge that is emitted during radioactive decay?
A beta particle
Which is high-energy radiation that has no electrical charge and no mass and is not deflected by electric or magnetic fields?
A gamma ray
Radiation that is deflected towards a negatively-charged plate when radiation from a radioactive source is directed between two electrically charged plates is called
Alpha radiation
Which is a particle with two protons and two neutrons that has a 2+ charge, is equivalent to a helium-4 nucleus, and is represented by the symbol α?
An alpha particle
A high-speed electron with a 1- charge that is emitted during radioactive decay is called a(n)
Beta particle
Radiation that is deflected toward a positively charged plate when directed between two electrically charged plates is called
Beta radiation
Which type of radiation is deflected toward a positively-charged plate when radiation from a radioactive source is directed between two electrically-charged plates?
Beta radiation
Gamma radiation has a ______.
Charge of 0 Mass of 0 amu
The particles that make up beta radiation have a ______.
Charge of 1- Mass of 1/1840 amu
Dalton's atomic theory supports the law of conservation of mass because in his theory, atoms are not created, _____ , or divided in a chemical reaction. Therefore, the total _____ before and after the reaction does not change.
Destroyed, mass
High-energy radiation that has no electrical charge and no mass and is not deflected by electric or magnetic fields is called a(n)
Gamma ray
When did scientists begin to be able to answer questions about the composition of the atom?
Late 1800s
Gamma radiation has a charge of _____ and a mass of _____ amu
Neutral, 0
The primary factor in determining an atom's stability is its ratio of
Neutrons to protons
A type of equation that shows the atomic number and mass number of the particles involved in a nuclear reaction is called a(n)
Nuclear equation
The type of equation shown here is called a(n) ______. 22688Ra ⇝ 22286Rn + α
Nuclear equation
A reaction that involves a change in an atom's nucleus is called a(n)
Nuclear reaction
Which is a spontaneous process in which unstable nuclei lose energy by emitting radiation?
Radioactive decay
In the late 1800s, scientists directed radiation between two electrically charged plates. They were able to identify ______ different types of radiation based on their _____ ______
Three, electric, charge
Nuclei that lose energy by emitting radiation through radioactive decay do so because they are _____. This decay continues until the nuclei become _____
Unstable, stable
Which type of radiation is deflected towards a negatively-charged plate when radiation from a radioactive source is directed between two electrically charged plates?
alpha
A particle with two protons and two neutrons that has a 2+ charge, is equivalent to a helium-4 nucleus, and is represented by the symbol α is called a(n)
alpha particle
In nuclear reactions, but not chemical reactions,
an element may change into another element.
The particles that make up alpha radiation have a ______.
charge of 2+ a mass of 4 amu 2 protons and 2 neutrons
Which is the primary factor in determining an atom's stability?
its ratio of neutrons to protons
Electron in amu
0.000549 amu
Which is the number of protons in an atom?
Atomic number
True or false: Democritus's ideas were rejected, in part, because the experiments he performed refuted his claims.
False: Science and the idea of doing controlled experiments did not exist during Democritus's time.
The mass of an electron is 1/1840 of the mass of a(n)
Hydrogen
Dalton and Democrtus' idea
Matter is made up of tiny particles that are indestructible and indivisible.
The atomic number is equal to the number of _____ in an atom. It is also equal to the number of ____ in an atom
Protons, electrons
The results of whose experiments are represented here?
Rutherford's
An element consists of two naturally occurring isotopes with the following masses and abundances. What is the atomic mass of the element?Isotope 1: 68.928 amu, 60.11%Isotope 2: 70.925 amu, 39.89%
69.72 average atomic mass = (68.928 amu)(0.6011) + (70.925 amu)(0.3989) = 69.72 amu
The unit of mass that is defined as one-twelfth the mass of a carbon-12 atom is the ____ _____ unit. Its symbol is _____
Atomic mass, amu
The atomic mass of an element is not a whole number because the atomic mass is the weighted ____ mass of the isotopes of that element, and isotopes have different ____
Average, masses
Radiation that originates from the cathode and travels to the anode of a cathode-ray tube is called a(n)
Cathode ray
J.J. Thomson's cathode-ray tube experiments in the late 1890s were designed to determine the ratio of an electron's ___ to its ___
Charge, mass
Many early philosophers concluded that matter was composed of four "elements":
Earth, air, fire and water
Aristotle did not believe that _____ _____ could not exist
Empty space
Which describe J.J. Thomson's model of the atom?
Its positive charge is uniformly distributed. It describes the atom as spherical. It is sometimes called the "plum pudding model."
Whose model of the atom is represented here?
J.J. Thomson's
Isotopes of an element have different ____ but the same chemical ____
Masses, properties
Which defines any reaction that involves a change in an atom's nucleus?
Nuclear reaction
The extremely small, positively charged, dense center of an atom that contains positively charged protons and neutral neutrons is the
Nucleus
Neutron: relative charge and mass
Relative charge= 0, relative mass= 1
Proton: relative charge and mass
Relative charge= 1+, relative mass= 1
The atomic mass of an element is not a whole number because ______.
atomic mass is the weighted average mass of an element's isotopes, which have different masses
Gallium has two naturally occurring isotopes, gallium-69 and gallium-71. Its atomic mass is 69.723 amu. Which isotope is more abundant?
gallium-69
One atomic mass unit (amu) is defined as ______.
one-twelfth the mass of a carbon-12 atom
Proton in amu
1.007276 amu
It was not until nearly 1900 that scientists began to be able to answer questions about the composition of the
Atom
Which is radiation that originates from the cathode and travels to the anode of a cathode-ray tube?
Cathode ray
Democritus proposed that matter was made up of atoms, which could not be
Created, destroyed, or further divided
Thomson's cathode ray-tube experiments led to the discovery of which subatomic particle?
Electron
All atoms are made up of the three fundamental subatomic particles
Protons, neutrons, and electrons
Which are characteristics of Rutherford's model of the atom?
a small nucleus that contains almost all of the atom's mass a small nucleus that contains the atom's positive charge electrons that are held within the atom by their electrical attraction to the nucleus
Which equations are correct for atoms?
number of protons = number of electrons atomic number = number of protons
Democritus proposed that
the atoms that made up matter could not be created, destroyed, or further divided. matter was made up of tiny particles called atomos (atoms). matter was not infinitely divisible.
In a given sample of silver found in nature, the percent abundance of silver-107 is 52.00%. In any other sample found in nature, the percent abundance of silver-107 will be ______.
52.00% In general, the relative abundance of each naturally occurring isotope is constant
Carbon has an atomic number of 6. Therefore, all neutral carbon atoms have ______ and ______
6 protons, 6 electrons
An element consists of two naturally occurring isotopes with the following masses and abundances. What is the atomic mass of the element?Isotope 1: 68.928 amu, 60.11%Isotope 2: 70.925 amu, 39.89%
69.72 amu (68.928 amu)(0.6011) + (70.925 amu)(0.3989) = 69.72 amu
Place these steps of Rutherford's gold foil experiment in order from first (top) to last (bottom).
A narrow beam of alpha particles was aimed at a thin sheet of gold foil A zinc-sulfide-coated screen produced a flash of light when struck by an alpha particle Researchers noted where the flashes occurred Researchers could then determine if the atoms in the gold foil deflected the alpha particles
Which statements about the charge and mass of subatomic particles are true?
A neutron is electrically neutral. The mass of a neutron is very slightly greater than the mass of a proton. Electrons and protons have equal and opposite charges.
In nature, the relative abundance of each isotope of an element is ______.
Almost always constant
Which statement best describes the design of Rutherford's gold foil experiment?
Alpha particles were fired through gold foil. Researchers noted whether the particles were deflected and by how much.
Rutherford conducted an experiment to see if _____ particles would be deflected as they passed through _____ _____
Alpha, gold, foil
Which question was Rutherford trying to answer with his gold foil experiment?
Are alpha particles deflected through a thin gold foil and if so, by how much?
Radioactive atoms emit radiation because their nuclei ______.
Are unstable
Which statements about the ideas of Democritus, Aristotle, and Dalton are true?
Aristotle believed that matter was made up of earth, air, fire, and water. Aristotle did not accept Democritus's ideas because he did not believe that empty space could exist. Both Dalton and Democritus proposed that matter is composed of extremely small particles.
The smallest particle of an element that retains the properties of the element is called a(n)
Atom
The weighted average mass of the isotopes of an element is the ____ ____ of the element
Atomic mass
Which is the weighted average mass of the isotopes of an element?
Atomic mass
The number of protons in an atom is the
Atomic number
Through his oil-drop experiments, Millikan was able to determine the ____ and _____ of an electron
Charge and mass
The change of one or more substances into new substances, involving only an atom's electrons, is a(n) ______ reaction. A reaction that may involve the change of one element into another is a(n) ______ reaction
Chemical, nuclear
John Dalton's ideas about matter, which arose from his many experiments in which he studied the mass ratios of elements involved in chemical reactions, are collectively known as
Dalton's atomic theory
What name is given to John Dalton's ideas about matter, which resulted from many careful measurements and observations?
Dalton's atomic theory
Dalton's idea
Different atoms combine in simple whole-number ratios to form compounds.
A negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus is called a(n)
Electron
Thomson's cathode-ray tube experiments led him to identify the first subatomic particle, the
Electron
Hydrogen has an atomic mass of 1.0079 amu and three naturally occurring isotopes: hydrogen-1, hydrogen-2, and hydrogen-3. Which isotope is the most abundant?
Hydrogen-1
Which statements are part of Dalton's atomic theory?
In a chemical reaction, atoms are separated, combined, or rearranged. Atoms of a specific element are different from those of another element. Atoms are indivisible and indestructible.
Atoms with the same number of protons but different numbers of neutrons are called
Isotopes
Which term is used for atoms with the same number of protons but different numbers of neutrons?
Isotopes
Aristotle
Matter is made of earth, air, fire, and water.
Which of these statements about atoms are true?
Most of the mass of an atom is in its nucleus. Atoms are mostly empty space containing fast-moving electrons.
A neutral, subatomic particle that has a mass nearly equal to that of a proton is a(n)
Neutron
Which is a neutral, subatomic particle that has a mass nearly equal to that of a proton?
Neutron
Which is the extremely small, dense center of an atom that contains the atom's positive charge and almost all of its mass?
Nucleus
A subatomic particle carrying a charge of 1+ is a(n)
Proton
Which of these subatomic particles are found in the nucleus of the atom?
Proton, neutron
The atomic number can be used to identify an atom because it is equal to the number of ____, which is a unique number for each element.
Protons
The atomic number, which is a unique number for each element, can be used to identify an atom because it is equal to the number of which subatomic particles?
Protons
The subatomic particles located in the nucleus of the atom are the _____ and neutrons. The subatomic particles that are found in the space surrounding the nucleus are the ______
Protons, electrons
Which is the process in which some substances spontaneously emit radiation? RadioactivityThe rays and particles—alpha and beta particles and gamma rays—that are emitted by radioactive materials are called
Radiation
Which term is used for the rays and particles—alpha and beta particles and gamma rays—that are emitted by radioactive materials?
Radiation
A spontaneous process in which unstable nuclei lose energy by emitting radiation is called
Radioactive decay
The process in which some substances spontaneously emit radiation is called
Radioactivity
Electron: relative charge and mass
Relative charge= 1-, relative mass= 1/1840
Whose model of the atom is represented here?
Rutherford's Not thomson's: Thomson's plum pudding model of the atom lacked a nucleus. Rather, the positive charge was uniformly distributed throughout the atom.
Which statement best describes the results of Rutherford's experiments?
Several particles were deflected straight back toward the source. Most alpha particles went straight through the gold foil. A few particles were deflected at large angles.
Which statements about the masses of protons, neutrons, and electrons are true?
The mass of an electron is 1/1840 that of a proton or neutron. The masses of protons and neutrons are approximately the same. The mass of a proton is 1.67 × 10^-24 g
Which is true of isotopes?
They have different masses but the same chemical properties.
Which is the smallest particle of an element that retains the properties of the element?
atom
According to Dalton's atomic theory,
atoms are separated, combined, or rearranged in a chemical reaction.
The device shown is called a(n) - _____. ______ ______
cathode-ray tube
What was Millikan able to determine through his oil-drop experiments?
charge and mass of an electron
Many early philosophers concluded that matter ______.
could be endlessly divided into smaller and smaller pieces was composed of earth, water, air, and fire
Several thousand years ago, science as we know it today ______.
did not exist
Which is a negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus?
electron
A cathode-ray tube
has metal electrodes connected to opposite ends. was used to study the relationship between mass and charge. depends on the use of a vacuum pump for its function.
Democritus's ideas were not accepted at the time he proposed them (or for thousands of years afterward) because
he was unable to back up his ideas with evidence from controlled experiments. Aristotle, one of the most influential Greek philosophers, did not support them. science as we know it did not exist.
The mass number ______.
identifies each isotope of an element is the sum of the number of protons and neutrons in a nucleus
The number that identifies each isotope of an element and is the sum of the number of protons and neutrons in the nucleus is the ____ number
mass
Aristotle believed that ______.
matter was made up earth, fire, air, and water
Democritus proposed that
matter was made up of tiny particles called atomos (atoms). the atoms that made up matter could not be created, destroyed, or further divided. matter was not infinitely divisible.
Which is a subatomic particle carrying a charge of 1+?
proton
What were J.J. Thomson's cathode-ray tube experiments in the late 1890s designed to determine?
the charge-to-mass ratio of an electron
Dalton's atomic theory explains the law of conservation of mass because, according to the theory,
the number of atoms of each type is the same before and after a reaction
Several thousand years ago, people sought after the truth about the nature of matter by ______.
thinking intellectually formulating explanations based on life experiences
