The three types of nuclear emission

Study guideThe atomIsotopes and ionsDetection of radioactivityThe three types of nuclear emissionHalf-lifeSafety precautions

Introduction

In this section, we explore the different types of radiation emitted by unstable nuclei, focusing on the nature of these emissions, their effects, and how they interact with electric and magnetic fields.

Emission of radiation from the nucleus

Radioactive decay is the process in which an unstable atomic nucleus emits radiation to become more stable. This process is:

Spontaneous: It happens naturally without any external influence.
Random in Direction: The emitted radiation can travel in any direction.

The emitted radiation comes in three main forms: alpha (α), beta (β), and gamma (γ) radiation.

Alpha, beta and gamma radiation

Alpha radiation

Nature of Radiation:

Composed of 2 protons and 2 neutrons.
Essentially the same as a helium nucleus.
It has a relatively large mass and positive charge.

Ionising Effects:

Highly ionising due to its large mass and double positive charge.
It can easily knock electrons out of atoms as it passes through materials.

Penetrating Abilities:

Low penetration. It can be stopped by a sheet of paper or a few centimeters of air.
It is dangerous if inhaled or ingested but cannot penetrate human skin.

Beta radiation

There are three main types of nuclear radiation, each with distinct characteristics:

Nature of Radiation:

Beta-minus (β⁻) particles are electrons emitted from the nucleus when a neutron decays into a proton.
Lightweight and negatively charged.

Ionising Effects:

Moderately ionising.
Its smaller size and lower charge make it less effective than alpha radiation at ionising atoms.

Penetrating Abilities:

Moderate penetration. It can be stopped by a few millimeters of aluminium or other light metals.
It can penetrate the skin but is blocked by denser materials.

Gamma radiation

Nature of Radiation:

Electromagnetic wave with no mass and no charge.
High-energy photons, similar to X-rays but even more energetic.

Ionising Effects:

Weakly ionising.
As a form of electromagnetic radiation, it is less likely to interact with atoms compared to charged particles like alpha and beta radiation.

Penetrating Abilities:

High penetration. It can pass through several centimeters of lead or meters of concrete.
It requires dense materials to effectively shield it.

The penetration power of alpha, beta and gamma radiation

Change in the nucleus

During alpha or beta decay, the nucleus changes to that of a different element. This is because the number of protons in the nucleus changes, and the number of protons determines the element.

In alpha decay, the nucleus loses two protons and two neutrons.
In beta decay, a neutron in the nucleus is converted into a proton and an electron, where the electron (called a beta particle) is emitted from the nucleus.

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