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WorksheetsHistorical Overview of Atomic Theory
Total questions: 40
Worksheet time: 20mins
Which scientist proposed that atoms are tiny, indivisible particles and used scientific evidence to support an atomic theory?
Ernest Rutherford finalized an evidence-based atomic theory
John Dalton developed an evidence-based atomic theory
Dmitri Mendeleev built an evidence-based atomic theory
J.J. Thomson formed an evidence-based atomic theory
What was J.J. Thomson’s key contribution to atomic structure?
He proved atoms are indivisible hard spheres
He organized elements into a periodic sequence
He discovered the nucleus with alpha scattering
He discovered the electron with cathode ray tubes
Which statement best describes the plum pudding model?
Neutral atoms made of solid positive spheres
Electrons embedded in a diffuse positive charge
Electrons orbiting a dense positive nucleus
Protons and neutrons arranged in shells
Rutherford’s gold foil experiment led to which conclusion about the atom?
Most mass is concentrated in a small nucleus
Electrons are spread evenly throughout atoms
Atoms are solid and indivisible spheres
Positive charge is uniformly distributed
Which scientist organized elements to reveal repeating chemical patterns, leading to the periodic table?
Dmitri Mendeleev created a periodic arrangement
John Dalton created a periodic arrangement
J.J. Thomson created a periodic arrangement
Ernest Rutherford created a periodic arrangement
Place these developments in the correct chronological order from earliest to latest: early Greek atom idea, Dalton’s theory, Thomson’s model, Rutherford’s nuclear model.
Greek idea → Thomson → Dalton → Rutherford
Dalton → Greek idea → Rutherford → Thomson
Thomson → Greek idea → Dalton → Rutherford
Greek idea → Dalton → Thomson → Rutherford
A student claims electrons are embedded within a positive sphere and that there is no nucleus. Which experiment most directly contradicts this claim?
Dalton’s gas law proportion measurements
Thomson’s cathode ray tube deflection test
Rutherford’s alpha particle scattering experiment
Mendeleev’s periodic classification study
Which idea from early Greek philosophers like Leucippus and Democritus influenced later science?
Matter is composed of tiny indivisible atoms
Atoms contain a central dense nucleus
Matter is continuous without smallest parts
Elements should be arranged by atomic mass
Which statement best describes the charge of the three fundamental particles?
Proton neutral, electron negative, neutron positive
Proton negative, electron positive, neutron neutral
Proton positive, electron negative, neutron neutral
Proton positive, electron neutral, neutron negative
Where are protons and neutrons located within an atom?
Evenly spread across all shells
Orbiting in outer energy levels
Mixed randomly with electrons
Together in the nucleus at the center
In the Bohr model, electrons are described as
Orbiting in defined energy levels
Attached permanently to protons
Stationary inside the nucleus
Moving randomly without shells
A neutral atom has which relationship between protons and electrons?
More electrons so net charge is negative
More protons so net charge is positive
Equal numbers so net charge is zero
Equal neutrons so net charge is zero
Quick rule: If electrons outnumber protons, the ion is
Negative due to extra electrons
Positive due to extra mass
Neutral due to balanced neutrons
Unstable due to missing nucleus
Which force holds the nucleus together to create nuclear binding energy?
Magnetic force aligning proton spins
Electrostatic force attracting electrons
Gravitational force pulling protons inward
Strong nuclear force overcoming proton repulsion
Electron-binding energy refers to the energy that
Creates the nucleus from quarks
Binds protons to neutrons
Holds electrons in shells
Accelerates electrons in a vacuum
Which statement about K-shell (inner-shell) electrons is accurate?
They carry no charge and sit in the nucleus
They are held tightly and need more energy to remove
They are held loosely and escape easily
They only exist in radioactive atoms
During Bremsstrahlung production in an x-ray tube, what happens to the fast electron?
It collides with a neutron, releasing heat only
It passes unaffected, producing no radiation
It is captured by the nucleus, emitting one energy
It is slowed near the nucleus, creating a spectrum
Bremsstrahlung radiation primarily contributes to which property of the x-ray beam?
Only high-energy characteristic peaks
A wide, continuous energy spectrum
A single, sharp energy spike
Only low-energy discrete lines
Characteristic radiation begins when which event occurs?
An inner-shell electron is ejected
A proton leaves the nucleus
A neutron splits into an electron
An outer-shell electron is added
Which process produces x-rays when a high-speed electron is slowed by the nucleus of a target atom?
Bremsstrahlung radiation
Characteristic radiation
Photoelectric effect
Pair production
Characteristic x-rays are created when an inner-shell vacancy is filled by an electron from which location?
Free space outside
A nearby nucleus
The same inner shell
An outer electron shell
What mainly determines the energy of a characteristic x-ray photon?
Difference between shell energies
Thickness of the anode target
Size of the x-ray tube
Speed of the cathode filament
Which statement best contrasts Bremsstrahlung and Characteristic radiation?
One is due to nucleus vibration, one is due to heat
Both come from electron braking at constant speed
Both require only outer-shell electrons moving outward
One is due to electron braking, one is due to shell transitions
According to the 2n² formula, what is the maximum number of electrons in the L shell (n=2)?
Twelve electrons maximum
Eight electrons maximum
Two electrons maximum
Four electrons maximum
Using 2n², how many electrons can the M shell (n=3) hold at most?
Sixteen electrons total
Eighteen electrons total
Twenty electrons total
Nine electrons total
What does the octet rule state about the outermost electron shell of many atoms?
It always holds exactly two electrons
It cannot accept any more electrons
It tends to hold up to eight electrons
It always contains an odd number
Which shell is closest to the nucleus in atomic structure naming?
N shell is closest
L shell is closest
K shell is closest
M shell is closest
Atoms with more shells, more electrons, and larger nuclei have what effect on x-ray interactions?
They increase the chance of interactions
They eliminate most interactions
They reduce all scatter formation
They stop producing any x-rays
In radiology, materials with higher atomic number (higher Z) most strongly affect which imaging factor?
Differential absorption and contrast
Tube heating and noise
Patient motion and blur
Detector pixel size
Which term describes two or more different elements bonded together?
Free proton
Single element
Isotopic atom
Compound substance
Which fact about the periodic table is most relevant to imaging?
It is sorted by density only
It is listed by melting point
It is arranged by atomic mass
It is organized by atomic number
Why are calcium and iodine highlighted for imaging applications?
They are high-Z elements used for bone and contrast
They are gases that reduce scatter in air
They are fuels that heat the x-ray tube
They are light elements that pass all x-rays
An unknown atom has three electron shells filled to maximum capacity following 2n². What is the total number of electrons in these three shells?
Thirty-two electrons total
Twenty-four electrons total
Twenty-eight electrons total
Fourteen electrons total
Two neutral atoms each have 20 protons. One has 20 neutrons, the other has 22 neutrons. What are these atoms to each other?
Ions with opposite charges
Isotopes of the same element
Isotones of different elements
Different elements entirely
Two atoms have the same number of neutrons but different numbers of protons. What are they called?
Ions
Isomers
Isotopes
Isotones
Which statement best describes ionic bonding in atoms?
Electrons are shared equally between two atoms
One atom transfers an electron to another atom
Nuclei merge to form a larger single nucleus
Neutrons move from one atom to another
What is the key feature of covalent bonding?
Electrons are shared between atoms
Electrons are ejected from the nucleus
Protons are exchanged between atoms
Neutrons are shared between atoms
Why do ionic and covalent interactions matter for radiologic imaging?
They determine image pixel matrix size
They influence differential absorption and image contrast
They reduce patient dose by lowering exposure time
They increase X‑ray tube heat production
A material forms complex atoms that boost photoelectric interactions. What imaging effect is most directly impacted?
Reduced geometric unsharpness
Faster image processing speed
Lower scatter with less noise
Greater differential absorption (higher contrast)
Covalent bonding is sometimes described with which electron path pattern between atoms?
Random spiral pattern between both atoms
Figure‑8 orbit pattern between both atoms
Straight line path across both atoms
Circular orbit pattern around both atoms
