Lecture on Radioactive Decay and Radiation

These flashcards cover key concepts from the lecture on radioactive decay and radiation, focusing on definitions, processes, and relevant materials.

Why do unstable nuclei give out radiation?

To become more stable through decay.

What is the process called when an unstable nucleus emits radiation?

Radioactive decay.

Define the activity of an unstable nucleus.

The rate of decay of a source of unstable nuclei.

What are the constituents of an alpha particle?

Two protons and two neutrons, equivalent to a helium nucleus.

What is the range of an alpha particle through air?

A few centimeters, typically between 2-10 cm.

What material can stop beta radiation?

A thin sheet of aluminium or several meters of air.

What material can stop gamma radiation?

Several centimeters of lead or a few meters of concrete.

What happens to mass and charge during the emission of a gamma ray?

Both mass and charge remain unchanged.

Describe the nature of radioactive decay.

It is random; which nuclei decays and when is determined by chance.

Define the half-life of a radioactive isotope.

The time it takes for the number of unstable nuclei to halve.

What is irradiation?

The process of exposing a material to nuclear radiation without making it radioactive.

Why is peer review important in radiation studies?

To allow findings to be independently checked.

What is emitted during radioactive decay to increase stability?

Radiation.

What does an increase in stability indicate about unstable nuclei?

The nuclei have undergone decay.

What is the significance of understanding radioactive decay?

It helps in predicting behavior of unstable isotopes.

What is unique about the decay timing of unstable nuclei?

It is impossible to predict which nuclei will decay and when.

How does radioactive decay affect the count rate of a sample?

The count rate falls to half its initial level over one half-life.

What form of radiation comprises two protons and two neutrons?

Alpha particle.

What type of radiation has a short range in air?

Alpha radiation.

What can be used to measure the activity of a radioactive source?

A Geiger counter or similar device.

How does the presence of a material affect its radioactivity during irradiation?

The material remains non-radioactive.

What is a common shield against beta radiation?

Aluminium.

What major factor prevents predicting radioactive decay?

Chance.

Is the half-life of a substance constant?

Yes, it is characteristic of the isotope.

In terms of radiation, what does exposure mean?

Being subjected to radioactive emissions.

What does a longer half-life indicate about a radioactive substance?

It will take longer to decay significantly.

What is a practical application of understanding half-lives?

Dating archaeological finds or medical treatments.

What happens to the properties of a radioactive substance during decay?

It changes, as unstable nuclei transform into more stable forms.

What kind of review ensures the credibility of radiation research findings?

Peer review.