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Atomic Theory and Structure
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Atomic Theory and Structure
Atomic Theory and Structure
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1
Question
Which scientist first used the term “atom” for smaller particles of matter?
Page 3
Answer
Democritus. He described matter as composed of smaller particles and used the term “atom.” Memory hook: Democritus was the ancient “atom inventor.”
2
Question
Which claim did Democritus make about the nature of atoms?
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Answer
He proposed that atoms were indestructible and indivisible. Memory hook: Democritus’s atoms were “unbreakable beads.”
3
Question
Which model represented Dalton’s view of the atom?
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Answer
A tiny, indivisible sphere. Memory hook: Dalton pictured atoms as perfectly solid “chemical marbles.”
4
Question
When did John Dalton formulate his atomic theory?
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Answer
1803. Memory hook: Dalton’s four postulates arrived at the “four-digit door,” 1803.
5
Question
Which statement describes Dalton’s first atomic postulate?
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Answer
Atoms are indivisible and cannot be separated. Memory hook: Dalton’s first rule is the “no-splitting marble” rule.
6
Question
How did Dalton distinguish atoms of different elements?
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Answer
Atoms of different elements are different from one another. Memory hook: oxygen and hydrogen wear different atomic uniforms.
7
Question
How do atoms form compounds according to Dalton’s theory?
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Answer
They combine in whole-number ratios. Memory hook: compounds are built with whole-number “atomic bricks.”
8
Question
What happens to atoms during a chemical reaction according to Dalton?
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Answer
Atoms are rearranged, not created or destroyed. Memory hook: chemical reactions are an “atomic rearrangement dance.”
9
Question
Which statement correctly compares atoms within and between elements?
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Answer
Atoms of one element are identical; atoms of different elements differ. Memory hook: same-element atoms wear matching uniforms, unlike different elements.
10
Question
How does whole-number combining relate to compound formation?
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Answer
Atoms of different elements can combine to form compounds in whole-number ratios. Memory hook: different atomic “teams” assemble in countable groups.
11
Question
Which scientist discovered the electron using a cathode ray tube?
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Answer
J. J. Thomson. Memory hook: Thomson found the tiny negative “crumb” inside the atom.
12
Question
Which charge did Thomson establish for the electron?
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Answer
The electron has a negative charge. Memory hook: Thomson’s electron is the atom’s negative “pepper flake.”
13
Question
How did Thomson’s plum pudding model describe atomic structure?
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Answer
Electrons were embedded in a positively charged mass. Memory hook: negative “plums” sit inside a positive pudding.
14
Question
Which quantity involving the electron did Thomson determine?
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Answer
The electron’s charge-to-mass ratio. Memory hook: Thomson carried a “charge-over-mass scale.”
15
Question
Which experiment did Millikan use to measure electron charge?
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Answer
The oil drop experiment. Memory hook: Millikan weighed floating “charged oil bubbles.”
16
Question
How did Millikan’s work support Thomson’s findings about electrons?
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Answer
Millikan confirmed that electrons have a negative charge. Memory hook: the oil drops stamped Thomson’s negative sign with approval.
17
Question
How did Millikan calculate the electron’s mass?
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Answer
He used Thomson’s charge-to-mass data. Memory hook: Millikan supplied the charge, then used Thomson’s ratio to unlock mass.
18
Question
Which particles did Goldstein discover with a cathode ray tube?
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Answer
Positive particles, later identified as protons. Memory hook: Goldstein found the atom’s positive “counterpart” to the electron.
19
Question
How does proton mass compare with electron mass?
Page 9
Answer
A proton has about 1 amu of mass, about 1840× the mass of an electron. Memory hook: the proton is the electron’s “1840-fold heavyweight.”
20
Question
Which experiment led Rutherford to discover the atomic nucleus?
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Answer
The gold foil experiment. Memory hook: Rutherford fired alpha particles at a thin gold “gate.”
21
Question
Why did Rutherford conclude that atoms are mostly empty space?
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Answer
Most alpha particles passed through the thin gold foil, while only a few bounced back. Memory hook: the atomic “stadium” was mostly open, with a tiny hard target.
22
Question
How does Rutherford’s model describe electron motion around the nucleus?
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Answer
Electrons travel around the nucleus like planets around the Sun. Memory hook: picture tiny planets orbiting a central Sun.
23
Question
Which particles does Rutherford’s model place inside the nucleus?
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Answer
Neutrons and protons. The nucleus is positively charged. Memory hook: the nucleus is a positively charged central fortress.
24
Question
How does the modern atomic model describe electron location?
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Answer
Electrons are found in electron clouds rather than planetary orbits. Memory hook: replace rigid tracks with a diffuse blue fog.
25
Question
What charge do electron clouds have around the nucleus?
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Answer
Electron clouds are negatively charged regions around the nucleus. Memory hook: the blue fog carries the negative charge.
26
Question
Which atomic particles each have a mass of about 1 amu?
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Answer
Protons and neutrons each have a mass of about 1 amu. Memory hook: the proton and neutron carry matching one-unit backpacks.
27
Question
How does an electron’s mass compare with 1 amu?
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Answer
An electron has a mass of approximately 1/1830 amu. Memory hook: the electron carries a nearly weightless backpack.
28
Question
Which symbol represents an electron and its charge?
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Answer
The electron is represented by e⁻ and has a charge of 1−. Memory hook: the electron’s minus sign is its permanent badge.
29
Question
Which symbol represents a proton and its charge?
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Answer
The proton is represented by p⁺ and has a charge of 1+. Memory hook: the proton wears a positive badge.
30
Question
Which symbol represents a neutron and its charge?
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Answer
The neutron is represented by n⁰ and has a charge of 0. Memory hook: the neutron carries a zero-sign shield.