NUCLEAR PHYSICS

What did Thomson's model propose about the atom?

The atom is like a plum pudding, with electrons embedded in a sphere of positive charge.

What experiment led to the replacement of Thomson's model?

Rutherford's gold foil experiment.

What did Rutherford's gold foil experiment reveal about the structure of the atom?

Most of the atom is empty space with a dense structure with a positive charge at the center, called the nucleus.

What are the key components of Rutherford's nuclear model of the atom?

The atom is mostly empty space, the nucleus is small, dense, and positively charged, and electrons revolve around the nucleus.

How do alpha particles interact with materials?

They are highly ionizing and have low penetration, stopped by 3 cm of air or a sheet of paper.

What is a key application of alpha radiation?

Used in smoke detectors because of high ionisation

What is the charge of beta particles?

They have a negative charge (they are high-energy electrons).

What is a primary application of beta radiation?

Used in radiation therapy to treat certain types of cancer.

How do gamma rays differ from alpha and beta radiation in terms of ionizing ability?

Gamma rays are low ionizing and interact minimally with material.

What is half-life?

The time required for half of the atoms in a sample of a radioactive isotope to decay.

How is half-life applied in real-world situations?

Used in carbon dating to determine the age of ancient artifacts and fossils.

Who discovered the neutron, and when?

James Chadwick in 1932.

What role do neutrons play in the nucleus?

They help stabilize the nucleus by reducing the repulsive forces between protons.

What are the three types of nuclear radiation?

Alpha (α), beta (β), and gamma (γ) radiation.

In what application is gamma radiation commonly used?

In medical imaging, such as PET scans, and in radiotherapy for treating cancer.

What do we mean by radioactive decay?

The spontaneous breakdown of an unstable atomic nucleus, releasing radiation.

What dictates the stability of an isotope?

The neutron-to-proton ratio in the nucleus.

What does the presence of neutrons in the nucleus explain?

It explains the extra mass in the nucleus that protons alone couldn't account for.

What is ionization energy?

The amount of energy required to remove an electron from an atom.

What is the relationship between atomic number and the number of protons?

The atomic number is equal to the number of protons in an atom.

How are isotopes defined?

Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons.

What is the function of a Geiger counter?

A device used to detect and measure ionizing radiation.

What is nuclear fission?

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

What are the primary products of nuclear fusion?

The fusion of light nuclei, such as hydrogen isotopes, produces helium and energy.

What is the main difference between nuclear fission and fusion?

Fission splits heavy nuclei, while fusion combines light nuclei.

What is a radioactive tracer?

A radioactive isotope used to track the movement of substances in a system.

What is the significance of the mass number?

The mass number is the total number of protons and neutrons in an atomic nucleus.

How does radiation affect living tissue?

Radiation can cause ionization in biological tissues, leading to cell damage or mutations.

What is radiation absorption?

The process by which materials take in radioactive particles or rays.

What is the trend of radiation use in medicine?

Radiation is increasingly used for diagnostics and treatment in medicine.

What is the principal health risk associated with ionizing radiation?

The risk of cancer due to cellular damage from ionization.

What are the factors that determine the effectiveness of radiation therapy?

Dose, type of radiation, and sensitivity of the tumor being treated.

How is the biological effect of radiation measured?

Using the dose equivalent measured in sieverts (Sv).

What is the difference between natural and artificial radiation?

Natural radiation comes from cosmic and terrestrial sources, while artificial radiation is generated by human activities.

What is the significance of the critical mass in nuclear fission?

The minimum mass of fissile material needed to sustain a chain reaction.

How does radiation therapy reduce tumor size?

By damaging the DNA of cancer cells, inhibiting their ability to proliferate.

What are the safety measures taken in handling radioactive materials?

Use of shielding, distance, and limiting exposure time.

What role do control rods play in a nuclear reactor?

They absorb neutrons to regulate the fission chain reaction.