Nuclear D2: Nuclear Decay Equations, Balancing and Half Life

FQ:  What's the difference between alpha, beta and gamma radiation?  How do we calculate with half life?

1.Watch

Radioactivity: Expect the Unexpected

2. Read

Alpha Decay

During alpha decay an unstable nucleus releases an alpha particle and energy. An alpha particle is made of two protons and two neutrons, and is actually a helium nucleus. The nuclide symbol is . Because the original nucleus (called the parent nucleus) loses 2 protons and 2two neutrons, its atomic number decreases by 2 and its mass number decreases by 4. It becomes a new element (called the daughter nucleus) that has an atomic number 2 lower than the original element. 

Beta Decay

During beta decay an unstable nucleus releases a beta particle and energy when a neutron becomes a proton. A beta particle can be either an electron or a positron, but we'll talk about the electron, from beta - decay. The symbol for a beta particle is . Electrons have masses much, much less than protons or neutrons so the mass of a beta particle is essentially 0. Electrons have a negative charge, so the -1 represents the particle's charge. During beta - decay the mass of the atom stays the same, but the atomic number increases by 1, turning the nucleus into a different element. 

Gamma Decay

During gamma decay, an unstable element releases its energy as a gamma particle but doesn't change the particles in its nucleus.  A gamma particle, or gamma ray, is a high-energy electromagnetic wave. It is similar to an x-ray but has even more energy. A gamma particle has no mass and no charge. The symbol for a gamma ray is . 

How Dangerous is Nuclear Radiation? 

When alpha, beta, or gamma particles are emitted by an atom, they are called nuclear radiation. All nuclear radiation can damage cells and DNA in your body, but some are blocked more easily than others. 

• Alpha particles, composed of two protons and two electrons, are comparatively large so a thin paper barrier will stop alpha particles. Alpha particles cannot penetrate skin, but are very dangerous if materials that release alpha particles are ingested or inhaled. They do the most damage to cells and DNA when inside the body.
• Beta particles, composed of electrons, can get through paper but have trouble penetrating a thicker sheet of aluminum. They can be mostly stopped by clothing, but are damaging if ingested or inhaled. 
• Gamma particles, composed of energy, have trouble getting through thick dense lead. Gamma rays can pass through all bodily tissue and cause damage to tissue and DNA. 

   

   

  

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3.  Half Life Simulation(for in-class work)