Nota Terkini

Monday, July 20, 2009

[Science Form 4] Emissions That Stabilise

A radioactive substance with an unstable nucleus gains stability by emitting rays. This process is known as disintegration or radioactive decay.

The rays emitted can be in three forms: alpha rays, beta rays and gamma rays. All three rays may not be emitted at the same time for each disintegration.

In the process of decay, energy is lost and the decayed atom forms a new stable atom.

Alpha (α) decay:
An α-particle consists of two protons and two neutrons, or a helium nucleus. When a substance undergoes decay and emits α rays, the rays cannot penetrate even a piece of paper.
An example of an α decay: Pu-239 -> U-235 + α

Beta (β)- decay:
A β-particle has the same mass and charge as an electron. In a β decay, a neutron is converted to a proton and a negative charge called β-particle is released. The β-particle can be stopped by a sheet of aluminium.

Gamma (γ) decay:
Gamma rays are high-power electromagnetic waves whose penetration power is high and can only be blocked by a thick lead or concrete.

nuclear fission - pembelahan nukleus
nuclear fusion - pelakuran nukleus
nuclear reactor - reaktor nuklear
penetration power - kuasa penembusan
radioactive decay - pereputan radioaktif


  1. cik gu ku yang satu ni memang blogger yang rajin...
    nice post...

  2. Salam kenal Cik, blognya bagus, tapi kalau bahasa inggris semua aku gak mudheng, bingung.