Ch. 9 - Atomic and Nuclear Phenomena

16% of MCAT Physics content

What is the photoelectric effect?

The ejection of an electron from the surface of a metal in response to light.

What is the threshold frequency?

The minimum light frequency necessary to eject an electron from a given metal.

What is the work function?

The minimum energy necessary to eject an electron from a given metal

calculated by multiplying the threshold frequency by Planck’s constant.

How does the energy of the incident photon affect the ejected electron?

The greater the energy of the photon above the work function, the more kinetic energy the ejected electron can possess.

How is the magnitude of the current in the photoelectric effect related to the light?

It is proportional to the intensity of the incident beam of light.

What does the Bohr model state about electron energy levels?

Electron energy levels are stable and discrete, corresponding to specific orbits.

How can an electron jump to a higher-energy orbit?

By absorbing a photon of light with the same frequency as the energy difference between the orbits.

What happens when an electron falls to a lower-energy orbit?

It emits a photon of light with the same frequency as the energy difference between the orbits.

How can absorption spectra be influenced?

By small changes in molecular structure.

What is fluorescence?

When a species absorbs high-frequency light and returns to its ground state in multiple steps, emitting visible light in the process.

What is nuclear binding energy?

The energy released when nucleons bind together, with greater binding energy indicating a more stable nucleus.

What are the four fundamental forces of nature?

Strong nuclear force, weak nuclear force, electrostatic force, and gravitation.

What is the mass defect?

The difference between the mass of unbonded nucleons and bonded nucleons, representing the mass converted to energy during nuclear fusion.

What is fusion?

The combination of small nuclei into larger nuclei, releasing energy.

What is fission?

The splitting of a large nucleus into smaller nuclei, releasing energy.

Why is energy released in both fusion and fission?

Because the nuclei formed in these processes are more stable than the starting nuclei.

What is radioactive decay?

The loss of small particles from the nucleus.

What is alpha (α) decay?

The emission of an alpha particle, which is a helium nucleus.

What is beta-negative (β−) decay?

The decay of a neutron into a proton, with emission of an electron (e−, β−) and an antineutrino.

What is beta-positive (β+) decay (positron emission)?

The decay of a proton into a neutron, with emission of a positron (e+, β+) and a neutrino.

What is gamma (γ) decay?

The emission of a gamma ray, converting a high-energy nucleus into a more stable nucleus.

What is electron capture?

The absorption of an electron from the inner shell, combining with a proton to form a neutron.

What is a half-life?

The time required for half of a sample of radioactive nuclei to decay.

What is exponential decay?

When the rate of radioactive decay is proportional to the number of nuclei remaining.