chemistry of life ch 2 quiz
Which model most accurately represents the current view of the structure of the atom?
Probability model We cannot determine the exact motion of electrons. We can only compute the regions where electrons occur most of the time. To emphasize the uncertainty, a diagram showing random motion is more suitable than planetary paths.
Which of these refers to atoms with the same atomic number but different atomic masses?
These atoms are isotopes. Atoms with the same atomic number and different atomic masses are referred to as isotopes.
Radioactive decay is likely to occur when ...
an atom has too many neutrons. The atomic nucleus becomes unstable if the ratio of protons to neutrons is too far from unity.
protons determine atomic number
characteristic for each element
electrons move in
electron cloud
neutrons determine mass number
may differ in isotopes
nucleus has ___ charge
no
neutrons located in
nucleus
protons located in
nucleus
Chemists assign atoms to chemical elements by counting their ________.
protons Elements are defined by the number of protons. Protons give an enduring basis for atomic behavior because they are permanently anchored in the nucleus, where their attraction determines how many electrons the atom can hold. By contrast, electrons come and go, and the numbers vary. Isotopes of the same element vary in the number of neutrons in the nucleus of the atom.
atoms have subatomic particles
protons neutrons electrons
Dr. Jones says an atom has 3 electrons in the first shell and four electrons in the second shell. Someone should tell Dr. Jones that ...
the first shell shouldn't have 3 electrons. The first shell can only have 0, 1, or 2 electrons.
Two atoms always represent the same element if they have ...
the same number of protons. The number of protons defines a chemical element. The number of neutrons and electrons can differ among atoms of the same element.
protons charge is
+1
electrons charge is
-1
Fluorine's atomic number is 9 and its atomic mass is 19. How many neutrons does fluorine have?
10 Atomic mass is equal to the number of protons plus the number of neutrons (19-9 = 10).
An atom has 8 protons, 8 neutrons, and 8 electrons. Another isotope of the same element might have ...
10 neutrons. Isotopes have the same number of protons; different numbers of neutrons.
An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have?
5 The atomic number is equal to the number of protons.
What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons?
6 This is an atom of carbon, an element with 6 protons. Atomic number is the number of protons in an atom.
The mass number of an atom is 15, and its atomic number is 7. The atom probably has...
8 neutrons in the nucleus The atomic number (7) gives the number of protons, and the mass number is the number of protons plus neutrons.
Which statement is true of the atom shown in the diagram?
An electron will move from the outer to the inner shell. The atom has more than one valence electron. The atom is in the excited state. The atom has a vacancy in its inner shell; an electron has moved to the outer (valence) shell. The result is an unstable excited state. An electron will move back to the inner shell, restoring the ground state as the atom gives off energy.
An atom has 6 electrons, 6 protons, and 6 neutrons. You can tell that this atom belongs to the element _____ because _____________________.
C; it has 6 protons. Atoms represent the element carbon (C) if they have six protons.
Which statement is true of atoms?
Electrons determine the atom's size. With electrons on the surface, atoms repel one another when they come too close. Thus, electrons determine the space that an atom occupies.
Which statement is true of the energy levels of electrons in shells?
The valence shell has higher energy than other occupied shells. The outer occupied shell is the valence shell, and outer shells hold electrons at higher energy than inner shells.