Expirement Observations
What device provided images of atomic-scale surfaces?
What is a scanning tunnelling microscope?
What is the charge of an electron?
What is −1?
Which type of radiation is stopped by paper?
What is alpha radiation?
What type of radiation makes up visible light?
What is electromagnetic radiation?
What is an atomic spectrum?
A pattern of specific wavelengths emitted or absorbed by an atom.
Why was direct observation of atoms not possible for scientists in the early days?
Atoms are too small to be seen with regular microscopes.
What is the charge of a proton?
What is +1?
Which type of radiation is stopped by aluminum?
What is beta radiation?
What property of light must be high enough for electrons to be emitted?
What is frequency?
Why does hydrogen emit only specific wavelengths?
Because electrons can only gain or lose specific amounts of energy.
According to the text, what type of evidence eventually convinced scientists that atoms exist?
Experimental and observational evidence.
Which subatomic particle has nearly the same mass as a proton but no charge?
What is the neutron?
Which type of radiation requires lead for shielding and travels at the speed of light?
What is gamma radiation?
Why does increasing brightness alone not eject electrons?
Brightness increases the number of photons, not their energy.
What type of spectrum does white light produce?
White light produces a continuous spectrum.
Why was experimenting more convincing than regular reasoning alone?
Because experiments provided real, measurable results.
Why did the discovery of the neutron help explain atomic mass?
Because neutrons add mass without changing charge.
Why is gamma radiation considered the most penetrating form of radiation?
It's pure energy with no mass or electrical charge, making it easy to pass through matter.
Why does increasing the brightness of light fail to eject electrons if the frequency is too low?
Because electron emission depends on the light’s frequency, not its intensity.
When hydrogen gas emits light, what type of spectrum is produced?
A line emission spectrum.
How did advances in technology change our understanding of atomic structure?
They allowed more accurate measurements and observation of subatomic behaviour.
Why can two atoms of the same element have different masses?
Because they have different numbers of neutrons (isotopes).
What two terms are used to describe the process by which an unstable nucleus changes on its own?
Spontaneous decay and disintegration.
What type of radiation makes up visible light within the electromagnetic spectrum?
Electromagnetic radiation.
What happens to an electron when it absorbs energy within an atom?
It moves to a higher energy level.