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Atomic Structure and Electron Energy
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Atomic Structure and Electron Energy
Atomic Structure and Electron Energy
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1
Question
Which subatomic particle determines an element’s atomic number?
Answer
The number of protons determines the atomic number. Elements are defined by their proton count.
2
Question
How does the proton’s charge compare with the fundamental charge?
Answer
A proton has a charge of +1 elementary charge, equal to approximately 1.6 × 10⁻¹⁹ C.
3
Question
Which subatomic particles make up nearly all atomic mass?
Answer
Protons and neutrons make up almost the entire mass of an atom.
4
Question
How is an atom’s mass number calculated from its nucleus?
Answer
The mass number, A, equals the sum of the protons and neutrons in the nucleus.
5
Question
How do isotopes of one element differ from one another?
Answer
Isotopes have the same atomic number but different mass numbers because they contain different numbers of neutrons.
6
Question
How does an electron’s charge compare with a proton’s charge?
Answer
An electron has the same charge magnitude as a proton but the opposite sign: −1 elementary charge.
7
Question
Why are electrons excluded from ordinary mass-number calculations?
Answer
Electrons have negligible mass compared with protons and neutrons, so they are not included in the mass number.
8
Question
Where are protons, neutrons, and electrons located?
Answer
Protons and neutrons are located in the nucleus. Electrons occupy orbitals surrounding the nucleus.
9
Question
How do valence electrons influence an atom’s reactivity?
Answer
Valence electrons are farthest from the nucleus, interact most strongly with the environment, and are most likely to participate in bonding.
10
Question
How does electron loss change an atom’s electrical charge?
Answer
Losing electrons gives the atom a positive charge and produces a cation.
11
Question
How does electron gain change an atom’s electrical charge?
Answer
Gaining electrons gives the atom a negative charge and produces an anion.
12
Question
How are proton and neutron masses related?
Answer
Both have relative masses of approximately 1 atomic mass unit, although the neutron is slightly more massive.
13
Question
How many protons, neutrons, and electrons does neutral nickel-58 contain?
Answer
Nickel-58 contains 28 protons, 30 neutrons, and 28 electrons.
14
Question
How many protons, neutrons, and electrons does nickel-60²⁺ contain?
Answer
Nickel-60²⁺ contains 28 protons, 32 neutrons, and 26 electrons.
15
Question
Which particle determines an atom’s charge, atomic number, and isotope?
Answer
Electrons determine charge, protons determine atomic number, and neutrons distinguish isotopes of the same element.
16
Question
How do atomic mass and mass number relate?
Answer
Atomic mass in atomic mass units is nearly equal to the mass number, which is the sum of protons and neutrons.
17
Question
How does atomic weight differ from atomic mass?
Answer
Atomic mass varies among isotopes, whereas atomic weight is the weighted average of naturally occurring isotopes of an element.
18
Question
Which quantity does the periodic table report for each element?
Answer
The periodic table reports atomic weight, not the exact atomic mass of one isotope.
19
Question
Why does chlorine have an atomic weight closer to 35 than 37?
Answer
Chlorine-35 is approximately three times more abundant than chlorine-37, so the weighted average is closer to 35.
20
Question
Why can no bromine atom have a mass of exactly 79.9 amu?
Answer
Bromine’s 79.9 amu value is a weighted average of bromine-79 and bromine-81, not the mass of an individual atom.
21
Question
Which three names identify hydrogen’s naturally occurring isotopes?
Answer
The isotopes are protium, deuterium, and tritium.
22
Question
How do protium, deuterium, and tritium differ?
Answer
Protium has one proton and no neutrons. Deuterium has one proton and one neutron. Tritium has one proton and two neutrons.
23
Question
Why do isotopes generally have similar chemical properties?
Answer
Isotopes have the same numbers of protons and electrons, producing similar electronic structures and chemical behavior.
24
Question
How is atomic weight related to molar mass?
Answer
Atomic weight represents the mass of an average atom in amu and the mass of one mole of the element in grams.
25
Question
Which value represents Avogadro’s number in the chapter?
Answer
Avogadro’s number is Nₐ = 6.02 × 10²³ entities per mole.
26
Question
How is an isotope mixture’s atomic weight calculated?
Answer
Multiply each isotope’s mass by its fractional abundance and add the products.
27
Question
What atomic weight results for an element with the listed isotope abundances?
Answer
For masses 40, 44, and 41 amu with abundances 60%, 25%, and 15%, the atomic weight is 41.15 amu.
28
Question
Who provided evidence for a dense positively charged nucleus?
Answer
Ernest Rutherford provided experimental evidence that atoms contain a dense, positively charged nucleus occupying only a small fraction of atomic volume.
29
Question
What did Planck propose about electromagnetic radiation energy?
Answer
Max Planck proposed that emitted electromagnetic energy occurs in discrete bundles called quanta.
30
Question
Which equation expresses Planck’s relation for photon energy?
Answer
The Planck relation is \(E = hf\), where \(h\) is Planck’s constant and \(f\) is radiation frequency.