UNIT 2 CHEM TEST BANK
Naturally occurring gallium is a mixture of isotopes that contains 60.11% of Ga-69(atomic mass = 68:93 u) and 39.89% of Ga-71 (atomic mass = 70:92 u). Which numerical setup can be used to determine the atomic mass of naturally occurring gallium?
(68.93 u)(0.6011) + (70.92 u)(0.3989)
What is the net charge of an ion that consists of 10 electrons, 11 protons, and 12 neutrons?
+1
Potassium forms an ion with a charge of...
+1 by losing one electron.
Which notations represent hydrogen isotopes?
1/1 H and 2/1 H.
What is the total number of electrons in a Mg+2 ion?
10
Which of the following nuclei is an isotope of 10p and 11n?
10p and 9n.
If X is the symbol of an element, which pair correctly represents isotopes of X?
158/64 X and 159/64 X
What is the number of electrons in a neutral potassium atom?
19
Which is the symbol for the deutrium isotope of hydrogen?
2/1 H
Which is the atomic number of an atom that forms an ion with 18 electrons and a charge of 2+?
20
What is the number of electrons in an atom of scandium?
21.
Which is the most abundant isotope found in a naturally occurring uranium deposit?
238/92 U
The maximum number of electrons that can occupy a principal energy level (n) of an atom is equal to...
2n^2
Which principal energy level can hold a maximum of eight electrons?
2nd
Which of the following identities the number and location of protons in a lithium atom?
3 protons, located in the nucleus.
What is the mass number in atomic mass units of an atom with 14 protons, 14 electrons, and 16 neutrons?
30 amu.
What is the maximum number of electrons that can be contained in then= 4 principal energy level?
32
How many protons are in an atom of bromine?
35
If 75.0% of the isotopes of an element have a mass of 35.0 amu and 25.0% of the isotopes have a mass of 37.0 amu, what is the atomic mass of the element?
35.5 amu
Which principal energy level can hold a maximum of 18 electrons?
3rd
An ion with 5 protons, 6 neutrons, and a charge of 3+ has an atomic number of...
5
How many protons and neutrons are there in an atom of 11/5 B?
5 protons and 6 neutrons.
What is the atomic number of carbon-14?
6
An atom has 29 protons, 29 electrons, and 35 neutrons. What is the mass number of the atom?
64
An element with an atomic number of 51 and an atomic mass of 121 has how many neutrons in each atom?
70
What is the maximum number of electrons that can occupy the second principal energy level?
8
Which best describes the current model of an atom?
A central nucleus containing protons and neutrons with electrons orbiting in levels of high probability.
Which of the following best describes an atom?
A core of protons and neutrons surrounded by electrons.
Which of the following comparisons correctly describes subatomic particles?
A neutron has a neutral charge and a mass larger than the mass of an electron.
Which particle has a mass that is approximately equal to the mass of a proton?
A neutron.
What is the relative size and location of a proton according to the Bohr-Rutherford model of the atom?
A proton is 2000 times more massive than an electron and is located in the nucleus.
What must occur when an electron in an atom returns from a higher energy state to a lower energy state?
A specific amount of energy is released.
The atomic mass of an element is the weighted average of the masses of...
All of its naturally occurring isotopes.
Which statement correctly compares an atom of boron-11 and an atom of carbon-14?
An atom of boron-11 has one fewer proton and two fewer neutrons than an atom of carbon-14.
Which of the following statements about the atom did Rutherford's experiment support?
An atom's nucleus is small and has a positive charge.
Which statement describes the charge of an electron and the charge of a proton?
An electron has a charge of -1, and a proton has a charge of +1.
Which statement describes the process during which an electron in an atom emits light?
An electron releases light energy as it moves from a higher energy level to a lower energy level.
Which particle has the least mass?
An electron.
Which atom has a net positive charge?
Atom Z.
Which statement best explains why most atomic masses on the Periodic Table are decimal numbers?
Atomic masses are a weighted average of the naturally occurring isotopes.
Atoms of every isotope of calcium have the same...
Atomic number.
Isotopes of the same element must have the same...
Atomic number.
The properties of elements are periodic functions of their...
Atomic numbers.
Which part of Dalton's atomic theory was disproved by further scientific research?
Atoms are indivisible particles.
Which one of these scientists described a model of the atom that included energy levels?
Bohr.
Chlorine has two naturally occurring isotopes, chlorine-35 and chlorine-37. The atomic mass of naturally occurring chlorine is 35.45. Which statement is correct?
Chlorine-35 is more abundant.
Which model best illustrates Thomson's explanation of the atom?
D
As an electron in a hydrogen atom moves from the second principal energy level to the first principal energy level, the energy of the atom...
Decreases.
What occurs when a magnesium atom becomes a magnesium ion?
Electrons are lost.
What causes an object to have a positive charge?
Electrons are removed.
The characteristic bright-line spectrum of an atom is produced when.
Electrons move from higher to lower energy levels.
Which of the following ideas was proposed by Niels Bohr?
Electrons occupy specific energy levels within an atom.
What was Niels Bohr's prediction about the location of the electrons in an atom?
Electrons orbit the nucleus in well-defined energy levels or orbitals.
During a flame test, ions of a specific metal are heated in the flame of a gas burner. A characteristic color of light is emitted by these ions in the flame when the electrons...
Emit energy as they return to lower energy levels.
Which occurs if an electron transitions from n= 5 to n= 2 in a hydrogen atom?
Energy is released, and visible light is emitted.
Compared to a calcium atom, the calcium ion Ca+2 has...
Fewer electrons.
Which best represents how electrons are arranged in the energy levels of a carbon atom?
First energy level = 2 electrons Second energy level = 4 electrons.
Which electron transition represents a gain of energy?
From 2nd to 3rd shell.
As an electron in an atom moves from the ground state to the excited state, the electron...
Gains energy as it moves to a higher energy level.
The characteristic spectral lines of elements are caused when electrons in an excited atom move from...
Higher to lower energy levels, releasing energy.
How do the energy and the most probable location of an electron in the third shell of an atom compare to the energy and the most probable location of an electron in the first shell of the same atom?
In the third shell, an electron has more energy and is farther from the nucleus.
Samples of I-131 and I-133 are classified as...
Isotopes of the same element.
Atomic masses are usually expressed as averages due to the existence of what phenomenon?
Isotopes.
Which statement best describes the part of the atom that is shown by the arrow?
It is an electron, and it has a negative charge.
When metals form ions, they tend to do so by...
Losing electrons and forming positive ions.
In the formula XSO4, the symbol X could represent the element
Mg.
A K atom differs from a K+ ion in that the K atom has one...
More electron.
Compared to a Be+2 ion, a Be0 atom has
More electrons.
Hydrogen has three isotopes with mass numbers of 1, 2, and 3 and has an average atomic mass of 1.00794 amu. This information indicates that...
More isotopes have an atomic mass of 1 than of 2 or 3.
The characteristic bright-line spectrum of an element occurs when electrons.
Move from higher to lower energy levels.
Which accounts for most of the mass of an atom?
Neutrons and protons.
Which phrase describes the charge and mass of a neutron?
No charge and an approximate mass of 1 u.
Wanda learned that deuterium (H-2), an isotope of hydrogen, has one proton and one neutron, and that protium (H-1) has one proton and no neutrons. She concluded that deuterium and protium are two different elements. Is this a valid conclusion?
No; the number of neutrons does not change the identity of the element; it merely creates heavier atoms of the same element.
How do the atoms of carbon-12 and carbon-14 differ?
Number of neutrons.
Isotopes are atoms that have the same number of protons but a different...
Number of neutrons.
Which distinguishes an atom of one element from an atom of a different element?
Number of protons.
Which term is defined as the region in an atom where an electron is most likely to be located?
Orbital.
The atomic number of an atom is always equal to the total number of...
Protons in the nucleus.
When electrons in an atom in an excited state fall to lower energy levels, energy is...
Released, only.
As an Na atom forms an Na+2 ion, the number of protons in its nucleus...
Remain the same.
As an atom becomes an ion, its mass number...
Remains the same.
As the mass number of the isotopes of hydrogen increases, the number of protons...
Remains the same.
Deuterium (2/1 H) are (1/1 H) and protium two isotopes of hydrogen. Which of the following statements best compares a deuterium atom to a protium atom?
The deuterium atom has more particles in its nucleus.
Which transition occurs when light with a wavelength of 434 nm is emitted by a hydrogen atom?
The electron falls from n= 5 to n= 2.
Which of the following did scientists learn about the atom from Rutherford's gold foil experiment?
The mass of an atom and its positive charge are concentrated in the nucleus.
Which statement describes the structure of an atom?
The nucleus has a positive charge and is surrounded by negatively charged electrons.
What information do the experimental results above reveal about the nucleus of the gold atom?
The nucleus is small and is the densest part of the atom.
Which statement best describes the density of an atom's nucleus?
The nucleus occupies very little of the atom's volume but contains most of its mass.
What characteristic is different in each isotope?
The number of neutrons in the nucleus.
Which principal energy level of an atom contains an electron with the lowest energy?
n = 1