Atomic Models and Radioactivity

These flashcards summarize key concepts related to atomic models, radioactivity, and the behavior of subatomic particles.

Who proposed that all matter is composed of atoms?

Democritus

What is the mass to charge ratio of cathode rays associated with?

Thompson's plum pudding model

Who developed the first working hypothesis of the atomic model?

Dalton

What did Rutherford use to show that the positive charge is concentrated in the center of atoms?

Scattering experiments with gold foil

What type of decay occurs without being affected by temperature or chemical bonding?

Radioactive decay as described by Curie

In which states can electrons exist according to Bohr?

Discrete quantized states

Who first described the photon nature of light?

Einstein

Which scientist demonstrated that photons have momentum?

Compton

Who introduced the concept that particles have wavelength?

DeBroglie

What kind of radiation is emitted during nuclear decay that involves electromagnetic radiation?

Gamma radiation

What type of nuclear decay involves high-speed electrons?

Beta decay

Which nuclear decay is considered the easiest to shield?

Alpha decay

What does a neutron decay into?

A beta particle (electron), a proton, and an antineutrino

What happens during nuclear reactions to increase stability in a large nucleus?

It emits alpha particles to become smaller

How does a neutron-rich nucleus become less neutron-rich?

It emits beta particles.

What happens to a nucleus that emits a gamma ray?

The nucleus becomes less energetic while retaining the same atomic number.

What is the atomic number of the daughter nucleus after a parent nucleus undergoes alpha decay?

It is 2 less than the parent nucleus.

What change occurs to the atomic number after a parent nucleus undergoes beta decay?

It is 1 greater than the parent nucleus.

What is the atomic number of the daughter nucleus after a parent nucleus undergoes gamma decay?

It remains the same as the parent nucleus.

If a radioactive source has a half-life, what would be the remaining quantity after 2 years if it started with a quantity of 1200 becherels?

1/16 of the original quantity.

How does the mass of a free proton compare to that of a proton bound in a nucleus?

The mass of a free proton is greater.

What is true regarding the mass of the Sun over time?

The Sun's mass is decreasing.

What is the source of the energy we receive from the Sun?

Nuclear fusion.

How does the total mass of products compare to reactants in fusion and fission reactions?

The mass of the products is less than that of the reactants.

What is the equation for nuclear fission of uranium?

It releases 2 neutrons.

Which of the following statements is true regarding photons?

Photons have wavelength.

Which statement correctly describes the energy of a single photon?

It is quantized and directly proportional to frequency.

What is the photoelectric effect?

Shining light on a cathode plate.

Which statements are true regarding the photoelectric effect?

Photoelectrons are emitted from a metal surface when light of high frequency falls on it.