What is an Alpha Particle?

Article Details
  • Written By: Michael Anissimov
  • Edited By: Bronwyn Harris
  • Last Modified Date: 21 October 2019
  • Copyright Protected:
    Conjecture Corporation
  • Print this Article
Free Widgets for your Site/Blog
Fr. Thomas Byles, who refused to leave the sinking Titanic and stayed to help others, is a candidate for sainthood.  more...

October 21 ,  1879 :  Thomas Edison lit up a light bulb for the first time.  more...

The alpha particle is a type of ionizing radiation. With its partners the gamma particles and beta particles, alpha particles are one of the most prevalent forms of radiation. Each particle is essentially a helium nucleus, which consists of two neutrons and two protons, without electrons, giving it a net positive charge. Due to their relatively high mass, these particles are the most destructive form of ionizing radiation, but the trade-off is that their penetration is low. A piece of paper stops alpha particles, whereas the lighter beta particles require a aluminum barrier.

Alpha particles are emitted from various radioactive substances. Unlike beta decay, alpha decay is mediated by the strong force. According to classical Newtonian laws, the attraction of the nucleus should be too strong to let alpha particles leave it under any circumstances. However, quantum tunneling permits it anyway. Quantum tunneling is the instantaneous teleporting of the particle to a place outside the nucleus.


Because alpha particles have such low penetrating force, they are stopped by human skin, presenting little danger unless the source is swallowed. This was the sad fate of Russian ex-spy Alexander Litvinenko, thought to be the first person to die from acute radiation poisoning as a result of ingesting the alpha emitter polonium. Other known alpha emitters include americium (found in smoke detectors), radium, radon gas, and uranium. When coupled together with certain other radioactive substances, alpha emitters can agitate neutron emitters to release the neutrons. Neutron emission is a critical part of nuclear reactor and nuclear weapons design.

In investigations into the health effects of smoking, it was found that tobacco leaves contain small amounts of polonium, which emits alpha particles. It is theorized that this could be partially responsible for lung cancer among smokers. In evolution, alpha emitters play a critical role — their likelihood of causing a chromosomal mutation is over 100 times greater than with other types of radiation. Most of the time, this produces less-fit mutants, but when combined with selection over thousands or millions of years results in adaptive biological designs.


You might also Like


Discuss this Article

Post 35

If an Alpha particle is a Helium nucleus, is it not easy to make it safe by adding two electrons to make the particle stable?

Post 30

I understand a little more. Thanks for the post. -Michigan

Post 25

Thank you tons for posting this. I understand much better now.I found this article to be interesting and pretty easy to understand.

Post 24

thank you for your help. now i actually know its use. thanks very much.

Post 20

I understand so much better now. Thank you.

Post 19

Thank you. It helped a lot.

Post 18

its kind of hard to understand. i think it needs to be explained more simply.

Post 16

This is an amazing factual piece of work. it really helped me answer my school homework questions

Post 14


Post 13

I finally understand it. thanks wisegeek! very detailed and exactly what i wanted. From apawsey

Post 12

So essentially an alpha particle is a messed up helium nucleus?

Post 10

can these particles ingested in water kill or cause cancers? and can these particles be generated in the waste pool of a nuclear plant?

Post 9

Very good piece of work. Very detailed piece.

Post 6


Post 4

this is absolutely outstanding.

Post 3

yay! thanks. i understand it now!

Post 2

Thank you for your article on Alpha particles. I'm studying for a radiography degree and its helped me hugely. Thanks guys

Post 1

Uhm... could this be explained really simply please? Kind of confusing... Thanks!

Post your comments

Post Anonymously


forgot password?