Chapter 3—Atoms and Moles
Chapter 3—Atoms and Moles
MULTIPLE CHOICE
1. The law of conservation of mass follows from the concept that
|a. |atoms are indivisible. |
|b. |atoms of different elements have different properties. |
|c. |matter is composed of atoms. |
|d. |atoms can be destroyed in chemical reactions. |
ANS: A PTS: 1 DIF: I OBJ: 3.1.1
2. The composition of the two oxides of lead, PbO and PbO2, are explained by the
|a. |periodic law. |c. |atomic law. |
|b. |law of multiple proportions. |d. |law of conservation of mass. |
ANS: B PTS: 1 DIF: II OBJ: 3.1.1
3. Who first proposed an atomic theory based on scientific knowledge?
|a. |John Dalton |c. |Robert Brown |
|b. |Jons Berzelius |d. |Dmitri Mendeleev |
ANS: A PTS: 1 DIF: I OBJ: 3.1.2
4. According to Dalton’s atomic theory, atoms
|a. |are destroyed in chemical reactions. |
|b. |can be divided. |
|c. |of each element are identical in size, mass, and other properties. |
|d. |of different elements cannot combine. |
ANS: C PTS: 1 DIF: I OBJ: 3.1.2
5. Which of the following is NOT part of Dalton’s atomic theory?
|a. |Atoms cannot be divided, created, or destroyed. |
|b. |The number of protons in an atom is its atomic number. |
|c. |In chemical reactions, atoms are combined, separated, or rearranged. |
|d. |All matter is composed of extremely small particles called atoms. |
ANS: B PTS: 1 DIF: I OBJ: 3.1.2
6. The law of definite proportions
|a. |contradicted Dalton’s atomic theory. |
|b. |was explained by Dalton’s atomic theory. |
|c. |replaced the law of conservation of mass. |
|d. |assumes that atoms of all elements are identical. |
ANS: B PTS: 1 DIF: I OBJ: 3.1.2
15. The mass of a neutron is
|a. |about the same as that of a proton. |c. |double that of a proton. |
|b. |about the same as that of an electron. |d. |double that of an electron. |
ANS: A PTS: 1 DIF: I OBJ: 3.2.1
16. The nucleus of most atoms is composed of
|a. |tightly packed protons. |
|b. |tightly packed neutrons. |
|c. |tightly packed protons and neutrons. |
|d. |loosely connected protons and electrons. |
ANS: C PTS: 1 DIF: I OBJ: 3.2.1
17. Protons and neutrons strongly attract when they
|a. |are moving fast. |c. |are at high energies. |
|b. |are very close together. |d. |have opposite charges. |
ANS: B PTS: 1 DIF: I OBJ: 3.2.1
18. An aluminum isotope consists of 13 protons, 13 electrons, and 14 neutrons. Its mass number is
|a. |13. |c. |27. |
|b. |14. |d. |40. |
ANS: C PTS: 1 DIF: II OBJ: 3.2.2
19. Isotopes are atoms of the same element that have different
|a. |principal chemical properties. |c. |numbers of protons. |
|b. |masses. |d. |numbers of electrons. |
ANS: B PTS: 1 DIF: I OBJ: 3.2.3
20. Atoms of the same element that have different masses are called
|a. |moles. |c. |nuclides. |
|b. |isotopes. |d. |neutrons. |
ANS: B PTS: 1 DIF: I OBJ: 3.2.3
21. Isotopes of an element contain different numbers of
|a. |electrons. |c. |neutrons. |
|b. |protons. |d. |nuclides. |
ANS: C PTS: 1 DIF: I OBJ: 3.2.3
COMPLETION
1. The statement that a chemical compound always contains the same elements in exactly the same proportions is called the law of _________________________.
ANS: definite proportions
PTS: 1 DIF: I OBJ: 3.1.1
2. The statement that mass cannot be created or destroyed in ordinary chemical and physical changes is called the law of _________________________.
ANS: conservation of mass
PTS: 1 DIF: I OBJ: 3.1.1
3. The statement that when two elements combine to form two or more compounds, the mass of one element that combines with a given mass of the other element is in the ratio of small whole numbers is known as the law of _________________________.
ANS: multiple proportions
PTS: 1 DIF: I OBJ: 3.1.1
4. A subatomic particle that has a negative electric change is a(n) ____________________.
ANS: electron
PTS: 1 DIF: I OBJ: 3.2.1
5. An atom’s central region, which is made up of protons and neutrons, is the ____________________.
ANS: nucleus
PTS: 1 DIF: I OBJ: 3.2.1
6. A subatomic particle that has a positive charge and that is found in the nucleus of an atom is a(n) ____________________.
ANS: proton
PTS: 1 DIF: I OBJ: 3.2.1
7. A subatomic particle that has no charge and is found in the nucleus is a(n) ____________________.
ANS: neutron
PTS: 1 DIF: I OBJ: 3.2.1
8. The number of protons in the nucleus of an atom is called the ____________________.
ANS: atomic number
PTS: 1 DIF: I OBJ: 3.2.2
9. The sum of the numbers of protons and neutrons of the nucleus of an atom is called the ____________________.
ANS: mass number
PTS: 1 DIF: I OBJ: 3.2.2
10. An atom that has the same number of protons as other atoms of the same element but has a different number of neutrons is called a(n) ____________________.
ANS: isotope
PTS: 1 DIF: I OBJ: 3.2.3
11. Another method of writing the nickel isotope, [pic], is ____________________.
ANS: nickel-58
PTS: 1 DIF: I OBJ: 3.2.3
12. A region in an atom where there is a high probability of finding electrons is called a(n) ____________________.
ANS: orbital
PTS: 1 DIF: I OBJ: 3.3.1
13. Orbitals are sometimes called electron ____________________ because they do not have hard boundaries.
ANS: clouds
PTS: 1 DIF: I OBJ: 3.3.1
14. All of the frequencies or wavelengths of electromagnetic radiation make up the electromagnetic ____________________.
ANS: spectrum
PTS: 1 DIF: I OBJ: 3.3.2
15. The wavelength of electromagnetic radiation is inversely proportional to its ____________________.
ANS: frequency
PTS: 1 DIF: II OBJ: 3.3.2
16. Light can be thought of as a stream of particles, the ____________________ of which is determined by the light’s frequency.
ANS: energy
PTS: 1 DIF: III OBJ: 3.3.2
17. A state in which an atom has more energy than it does in its ground state is called a(n) ____________________.
ANS: excited state
PTS: 1 DIF: I OBJ: 3.3.2
18. A number that specifies a property of an orbital is called a(n) ____________________.
ANS: quantum number
PTS: 1 DIF: I OBJ: 3.3.3
19. The statement that two particles of a certain class cannot be in the exact same energy state is known as the ____________________ principle.
ANS: Pauli exclusion
PTS: 1 DIF: I OBJ: 3.3.4
20. The _________________________ of an atom is the arrangement of its electrons.
ANS: electron configuration
PTS: 1 DIF: I OBJ: 3.3.4
21. The statement that the structure of each successive element is obtained by adding one proton to the nucleus of the atom and one electron to the lowest-energy orbital that is available is known as the ____________________ principle.
ANS: aufbau
PTS: 1 DIF: I OBJ: 3.3.4
22. The statement that for an atom in the ground state, the number of unpaired electrons is the maximum possible and these unpaired electrons have the same spin is known as ____________________ rule.
ANS: Hund’s
PTS: 1 DIF: I OBJ: 3.3.4
23. The mass of an atom expressed in atomic mass units is the ____________________.
ANS: atomic mass
PTS: 1 DIF: I OBJ: 3.4.1
24. The SI base unit used to measure the amount of a substance whose number of particles is the same as the number of particles in 12 g of carbon-12 is called the ____________________.
ANS: mole
PTS: 1 DIF: I OBJ: 3.4.2
25. Avogadro’s number has a value (to three significant figures) of ____________________.
ANS: 6.02 × 1023
PTS: 1 DIF: I OBJ: 3.4.2
26. The mass in grams of 1 mol of a substance is the substance’s ____________________.
ANS: molar mass
PTS: 1 DIF: I OBJ: 3.4.2
SHORT ANSWER
1. What is the atomic number of the atom [pic] ?
ANS:
15
PTS: 1 DIF: I OBJ: 3.2.2
2. What is the mass number of the atom [pic] ?
ANS:
86
PTS: 1 DIF: I OBJ: 3.2.2
3. How many electrons are in a neutral atom of [pic] ?
ANS:
56
PTS: 1 DIF: I OBJ: 3.2.2
4. How many protons are in an atom of [pic] ?
ANS:
40
PTS: 1 DIF: I OBJ: 3.2.2
5. How many neutrons are in an atom of [pic] ?
ANS:
82
PTS: 1 DIF: I OBJ: 3.2.2
6. What is the molar mass of tin, which has an atomic mass of 118.7 amu?
ANS:
118.7 g/mol
PTS: 1 DIF: I OBJ: 3.2.2
PROBLEM
1. What is the mass of 2.5 moles of carbon?
ANS:
[pic]
PTS: 1 DIF: II OBJ: 3.4.3
2. How many moles of copper are present in 180.0 g Cu?
ANS:
[pic]
PTS: 1 DIF: II OBJ: 3.4.3
3. The mass of 1 mol of gold atoms is 196.97 g. Find the mass of 1 atom of gold.
ANS:
[pic]
PTS: 1 DIF: III OBJ: 3.4.3
4. How many atoms are in 0.12 mol of cadmium?
ANS:
[pic]
PTS: 1 DIF: II OBJ: 3.4.3
ESSAY
1. Describe atomic mass.
ANS:
Atomic mass is the sum of the masses of the total number of protons and neutrons in the atom.
PTS: 1 DIF: I OBJ: 3.2.2
2. Describe the atomic mass unit.
ANS:
The atomic mass unit is the average of the mass of the protons and neutrons in the carbon-12 isotope.
PTS: 1 DIF: I OBJ: 3.4.1
3. How are the atomic mass unit and the atomic mass related?
ANS:
The atomic mass is the atomic mass unit multiplied by the number of protons and neutrons in the atom.
PTS: 1 DIF: I OBJ: 3.4.1
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